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Canvas(3)             User Contributed Perl Documentation            Canvas(3)




NAME

       Tk::Canvas - Create and manipulate Canvas widgets


SYNOPSIS

       $canvas = $parent->Canvas(?options?);


STANDARD OPTIONS

       -background    -highlightthickness -insertwidth   -state
       -borderwidth   -insertbackground   -relief   -tile
       -cursor   -insertborderwidth  -selectbackground   -takefocus
       -highlightbackground     -insertofftime -selectborderwidth  -xscrollcommand
       -highlightcolor     -insertontime  -selectforeground   -yscrollcommand


WIDGET-SPECIFIC OPTIONS

       Name:     closeEnough
       Class:    CloseEnough
       Switch:   -closeenough
           Specifies a floating-point value indicating how close the mouse
           cursor must be to an item before it is considered to be ``inside''
           the item.  Defaults to 1.0.

       Name:     confine
       Class:    Confine
       Switch:   -confine
           Specifies a boolean value that indicates whether or not it should
           be allowable to set the canvas's view outside the region defined by
           the scrollRegion argument.  Defaults to true, which means that the
           view will be constrained within the scroll region.

       Name:     height
       Class:    Height
       Switch:   -height
           Specifies a desired window height that the canvas widget should
           request from its geometry manager.  The value may be specified in
           any of the forms described in the "COORDINATES" section below.

       Name:     scrollRegion
       Class:    ScrollRegion
       Switch:   -scrollregion
           Specifies a list with four coordinates describing the left, top,
           right, and bottom coordinates of a rectangular region.  This region
           is used for scrolling purposes and is considered to be the boundary
           of the information in the canvas.  Each of the coordinates may be
           specified in any of the forms given in the "COORDINATES" section
           below.

       Name:     state
       Class:    State
       Switch:   -state
           Modifies the default state of the canvas where state may be set to
           one of: normal, disabled, or hidden. Individual canvas objects all
           have their own state option, which overrides the default state.
           Many options can take separate specifications such that the
           appearance of the item can be different in different situations.
           The options that start with "active" control the appearence when
           the mouse pointer is over it, while the option starting with
           "disabled" controls the appearence when the state is disabled.

       Name:     width
       Class:    width
       Switch:   -width
           Specifies a desired window width that the canvas widget should
           request from its geometry manager.  The value may be specified in
           any of the forms described in the "COORDINATES" section below.

       Name:     xScrollIncrement
       Class:    ScrollIncrement
       Switch:   -xscrollincrement
           Specifies an increment for horizontal scrolling, in any of the
           usual forms permitted for screen distances.  If the value of this
           option is greater than zero, the horizontal view in the window will
           be constrained so that the canvas x coordinate at the left edge of
           the window is always an even multiple of xScrollIncrement;
           furthermore, the units for scrolling (e.g., the change in view when
           the left and right arrows of a scrollbar are selected) will also be
           xScrollIncrement.  If the value of this option is less than or
           equal to zero, then horizontal scrolling is unconstrained.

       Name:     yScrollIncrement
       Class:    ScrollIncrement
       Switch:   -yscrollincrement
           Specifies an increment for vertical scrolling, in any of the usual
           forms permitted for screen distances.  If the value of this option
           is greater than zero, the vertical view in the window will be
           constrained so that the canvas y coordinate at the top edge of the
           window is always an even multiple of yScrollIncrement;
           furthermore, the units for scrolling (e.g., the change in view when
           the top and bottom arrows of a scrollbar are selected) will also be
           yScrollIncrement.  If the value of this option is less than or
           equal to zero, then vertical scrolling is unconstrained.


DESCRIPTION

       The Canvas method creates a new window (given by the $canvas argument)
       and makes it into a canvas widget.  Additional options, described
       above, may be specified on the command line or in the option database
       to configure aspects of the canvas such as its colors and 3-D relief.
       The canvas command returns its $canvas argument.  At the time this
       command is invoked, there must not exist a window named $canvas, but
       $canvas's parent must exist.

       Canvas widgets implement structured graphics.  A canvas displays any
       number of items, which may be things like rectangles, circles, lines,
       and text.  Items may be manipulated (e.g. moved or re-colored) and
       callbacks may be associated with items in much the same way that the
       bind method allows callbacks to be bound to widgets.  For example, a
       particular callback may be associated with the <Button-1> event so that
       the callback is invoked whenever button 1 is pressed with the mouse
       cursor over an item.  This means that items in a canvas can have
       behaviors defined by the Callbacks bound to them.


DISPLAY LIST

       The items in a canvas are ordered for purposes of display, with the
       first item in the display list being displayed first, followed by the
       next item in the list, and so on.  Items later in the display list
       obscure those that are earlier in the display list and are sometimes
       referred to as being ``on top'' of earlier items.  When a new item is
       created it is placed at the end of the display list, on top of
       everything else.  Widget methods may be used to re-arrange the order of
       the display list.

       Window items are an exception to the above rules.  The underlying
       window systems require them always to be drawn on top of other items.
       In addition, the stacking order of window items is not affected by any
       of the canvas methods; you must use the raise and lower Tk widget
       methods instead.


ITEM IDS AND TAGS

       Items in a canvas widget may be named in either of two ways: by id or
       by tag.  Each item has a unique identifying number which is assigned to
       that item when it is created.  The id of an item never changes and id
       numbers are never re-used within the lifetime of a canvas widget.

       Each item may also have any number of tags associated with it.  A tag
       is just a string of characters, and it may take any form except that of
       an integer.  For example, ``x123'' is OK but ``123'' isn't.  The same
       tag may be associated with many different items.  This is commonly done
       to group items in various interesting ways;  for example, all selected
       items might be given the tag ``selected''.

       The tag all is implicitly associated with every item in the canvas;  it
       may be used to invoke operations on all the items in the canvas.

       The tag current is managed automatically by Tk; it applies to the
       current item, which is the topmost item whose drawn area covers the
       position of the mouse cursor.  If the mouse is not in the canvas widget
       or is not over an item, then no item has the current tag.

       When specifying items in canvas methods, if the specifier is an integer
       then it is assumed to refer to the single item with that id.  If the
       specifier is not an integer, then it is assumed to refer to all of the
       items in the canvas that have a tag matching the specifier.  The symbol
       tagOrId is used below to indicate that an argument specifies either an
       id that selects a single item or a tag that selects zero or more items.

       tagOrId may contain a logical expressions of tags by using operators:
       '&&', '||', '^' '!', and parenthezised subexpressions.  For example:

       $c->find('withtag',  '(a&&!b)|(!a&&b)');

       or equivalently:

       $c->find('withtag', 'a^b');

       will find only those items with either "a" or "b" tags, but not both.

       Some methods only operate on a single item at a time;  if tagOrId is
       specified in a way that names multiple items, then the normal behavior
       is for the methods is to use the first (lowest) of these items in the
       display list that is suitable for the method.  Exceptions are noted in
       the method descriptions below.


COORDINATES

       All coordinates related to canvases are stored as floating-point
       numbers.  Coordinates and distances are specified in screen units,
       which are floating-point numbers optionally followed by one of several
       letters.  If no letter is supplied then the distance is in pixels.  If
       the letter is m then the distance is in millimeters on the screen;  if
       it is c then the distance is in centimeters; i means inches, and p
       means printers points (1/72 inch).  Larger y-coordinates refer to
       points lower on the screen;  larger x-coordinates refer to points
       farther to the right.


TRANSFORMATIONS

       Normally the origin of the canvas coordinate system is at the upper-
       left corner of the window containing the canvas.  It is possible to
       adjust the origin of the canvas coordinate system relative to the
       origin of the window using the xview and yview methods;  this is
       typically used for scrolling.  Canvases do not support scaling or
       rotation of the canvas coordinate system relative to the window
       coordinate system.

       Individual items may be moved or scaled using methods described below,
       but they may not be rotated.


INDICES

       Text items support the notion of an index for identifying particular
       positions within the item.

       Indices are used for methods such as inserting text, deleting a range
       of characters, and setting the insertion cursor position.  An index may
       be specified in any of a number of ways, and different types of items
       may support different forms for specifying indices.

       In a similar fashion, line and polygon items support index for
       identifying, inserting and deleting subsets of their coordinates.
       Indices are used for commands such as inserting or deleting a range of
       characters or coordinates, and setting the insertion cursor position.
       An index may be specified in any of a number of ways, and different
       types of items may support different forms for specifying indices.

       Text items support the following forms for an index;  if you define new
       types of text-like items, it would be advisable to support as many of
       these forms as practical.  Note that it is possible to refer to the
       character just after the last one in the text item;  this is necessary
       for such tasks as inserting new text at the end of the item.  Lines and
       Polygons don't support the insertion cursor and the selection. Their
       indices are supposed to be even always, because coordinates always
       appear in pairs.

       number
           A decimal number giving the position of the desired character
           within the text item.  0 refers to the first character, 1 to the
           next character, and so on. If indexes are odd for lines and
           polygons, they will be automatically decremented by one.  A number
           less than 0 is treated as if it were zero, and a number greater
           than the length of the text item is treated as if it were equal to
           the length of the text item. For polygons, numbers less than 0 or
           greater then the length of the coordinate list will be adjusted by
           adding or substracting the length until the result is between zero
           and the length, inclusive.

       end Refers to the character or coordinate just after the last one in
           the item (same as the number of characters or coordinates in the
           item).

       insert
           Refers to the character just before which the insertion cursor is
           drawn in this item. Not valid for lines and polygons.

       sel.first
           Refers to the first selected character in the item.  If the
           selection isn't in this item then this form is illegal.

       sel.last
           Refers to the last selected character in the item.  If the
           selection isn't in this item then this form is illegal.

       [x,y]
           Refers to the character or coordinate at the point given by x and
           y, where x and y are specified in the coordinate system of the
           canvas.  If x and y lie outside the coordinates covered by the text
           item, then they refer to the first or last character in the line
           that is closest to the given point.  The Tcl string form "@x,y" is
           also allowed.


DASH PATTERNS

       Many items support the notion of an dash pattern for outlines.

       The first possible syntax is a list of integers. Each element
       represents the number of pixels of a line segment. Only the odd
       segments are drawn using the "outline" color. The other segments are
       drawn transparent.

       The second possible syntax is a character list containing only 5
       possible characters [.,-_ ],  with the first 4 characters producing a
       segment of length 1 to 4, respectively, followed by a transparent
       segment of length 2. The space can be used repeatedly to enlarge the
       space between other line elements by 1, and can not occur as the first
       position in the string.  The main difference of this syntax with the
       previous one is that it it shape-conserving. This means that all values
       in the dash list will be multiplied by the line width before display.
       This assures that "." will always be displayed as a dot and "-" always
       as a dash regardless of the line width.

       Some examples, for a line width of 2:

        -dash .     = -dash [2,4]
        -dash -     = -dash [6,4]
        -dash -.    = -dash [6,4,2,4]
        -dash -..   = -dash [6,4,2,4,2,4]
        -dash '.  ' = -dash [2,8]
        -dash ','   = -dash [4,4]

       On systems where only a limited set of dash patterns is available, the
       dash pattern will be displayed as the closest available dash pattern.
       For example, on Windows only the first 4 of the above examples are
       available. The last 2 examples will be displayed identically as the
       first one.


WIDGET METHODS

       The Canvas method creates a widget object.  This object supports the
       configure and cget methods described in Tk::options which can be used
       to enquire and modify the options described above.  The widget also
       inherits all the methods provided by the generic Tk::Widget class.

       The following additional methods are available for canvas widgets:

       $canvas->addtag(tag, searchSpec, ?arg, arg, ...?)
           For each item that meets the constraints specified by searchSpec
           and the args, add tag to the list of tags associated with the item
           if it isn't already present on that list.  It is possible that no
           items will satisfy the constraints given by searchSpec and args, in
           which case the method has no effect.  This command returns an empty
           string as result.  SearchSpec and arg's may take any of the
           following forms:

           above tagOrId
                   Selects the item just after (above) the one given by
                   tagOrId in the display list.  If tagOrId denotes more than
                   one item, then the last (topmost) of these items in the
                   display list is used.

           all     Selects all the items in the canvas.

           below tagOrId
                   Selects the item just before (below) the one given by
                   tagOrId in the display list.  If tagOrId denotes more than
                   one item, then the first (lowest) of these items in the
                   display list is used.

           closest x y ?halo? ?start?
                   Selects the item closest to the point given by x and y.  If
                   more than one item is at the same closest distance (e.g.
                   two items overlap the point), then the top-most of these
                   items (the last one in the display list) is used.  If halo
                   is specified, then it must be a non-negative value.  Any
                   item closer than halo to the point is considered to overlap
                   it.  The start argument may be used to step circularly
                   through all the closest items.  If start is specified, it
                   names an item using a tag or id (if by tag, it selects the
                   first item in the display list with the given tag).
                   Instead of selecting the topmost closest item, this form
                   will select the topmost closest item that is below start in
                   the display list;  if no such item exists, then the
                   selection behaves as if the start argument had not been
                   specified.

           enclosed x1 y1 x2 y2
                   Selects all the items completely enclosed within the
                   rectangular region given by x1, y1, x2, and y2.  X1 must be
                   no greater then x2 and y1 must be no greater than y2.

           overlapping x1 y1 x2 y2
                   Selects all the items that overlap or are enclosed within
                   the rectangular region given by x1, y1, x2, and y2.  X1
                   must be no greater then x2 and y1 must be no greater than
                   y2.

           withtag tagOrId
                   Selects all the items given by tagOrId.

       $canvas->bbox(tagOrId, ?tagOrId, tagOrId, ...?)
           Returns a list with four elements giving an approximate bounding
           box for all the items named by the tagOrId arguments.  The list has
           the form ``x1 y1 x2 y2'' such that the drawn areas of all the named
           elements are within the region bounded by x1 on the left, x2 on the
           right, y1 on the top, and y2 on the bottom.  The return value may
           overestimate the actual bounding box by a few pixels.  If no items
           match any of the tagOrId arguments or if the matching items have
           empty bounding boxes (i.e. they have nothing to display) then an
           empty string is returned.

       $canvas->bind(tagOrId?, sequence? ?,callback?)
           This method associates callback with all the items given by tagOrId
           such that whenever the event sequence given by sequence occurs for
           one of the items the callback will be invoked.  This method is
           similar to the bind method except that it operates on items in a
           canvas rather than entire widgets.  See Tk::bind for complete
           details on the syntax of sequence and the substitutions performed
           on callback before invoking it.  If all arguments are specified
           then a new binding is created, replacing any existing binding for
           the same sequence and tagOrId (if the first character of command is
           ``+'' then command augments an existing binding rather than
           replacing it).  In this case the return value is an empty string.
           If callback is omitted then the method returns the callback
           associated with tagOrId and sequence (an error occurs if there is
           no such binding).  If both callback and sequence are omitted then
           the method returns a list of all the sequences for which bindings
           have been defined for tagOrId.

                   The only events for which bindings may be specified are
                   those related to the mouse and keyboard (such as Enter,
                   Leave, ButtonPress, Motion, and KeyPress) or virtual
                   events.  The handling of events in canvases uses the
                   current item defined in "ITEM IDS AND TAGS" above.  Enter
                   and Leave events trigger for an item when it becomes the
                   current item or ceases to be the current item; note that
                   these events are different than Enter and Leave events for
                   windows.  Mouse-related events are directed to the current
                   item, if any.  Keyboard-related events are directed to the
                   focus item, if any (see the focus method below for more on
                   this).  If a virtual event is used in a binding, that
                   binding can trigger only if the virtual event is defined by
                   an underlying mouse-related or keyboard-related event.

                   It is possible for multiple bindings to match a particular
                   event.  This could occur, for example, if one binding is
                   associated with the item's id and another is associated
                   with one of the item's tags.  When this occurs, all of the
                   matching bindings are invoked.  A binding associated with
                   the all tag is invoked first, followed by one binding for
                   each of the item's tags (in order), followed by a binding
                   associated with the item's id.  If there are multiple
                   matching bindings for a single tag, then only the most
                   specific binding is invoked.  A continue in a callback
                   terminates that subroutine, and a break method terminates
                   that subroutine and skips any remaining callbacks for the
                   event, just as for the bind method.

                   If bindings have been created for a canvas window using the
                   CanvasBind method, then they are invoked in addition to
                   bindings created for the canvas's items using the bind
                   method.  The bindings for items will be invoked before any
                   of the bindings for the window as a whole.

       $canvas->canvasx(screenx?, gridspacing?)
           Given a window x-coordinate in the canvas screenx, this method
           returns the canvas x-coordinate that is displayed at that location.
           If gridspacing is specified, then the canvas coordinate is rounded
           to the nearest multiple of gridspacing units.

       $canvas->canvasy(screeny, ?gridspacing?)
           Given a window y-coordinate in the canvas screeny this method
           returns the canvas y-coordinate that is displayed at that location.
           If gridspacing is specified, then the canvas coordinate is rounded
           to the nearest multiple of gridspacing units.

       $canvas->coords(tagOrId ?x0,y0 ...?)
           Query or modify the coordinates that define an item.  If no
           coordinates are specified, this method returns a list whose
           elements are the coordinates of the item named by tagOrId.  If
           coordinates are specified, then they replace the current
           coordinates for the named item.  If tagOrId refers to multiple
           items, then the first one in the display list is used.

       $canvas->create(type, x, y, ?x, y, ...?, ?option, value, ...?)
           Create a new item in $canvas of type type.  The exact format of the
           arguments after type depends on type, but usually they consist of
           the coordinates for one or more points, followed by specifications
           for zero or more item options.  See the subsections on individual
           item types below for more on the syntax of this method.  This
           method returns the id for the new item.

       $canvas->dchars(tagOrId, first, ?last?)
           For each item given by tagOrId, delete the characters, or
           coordinates, in the range given by first and last, inclusive.  If
           some of the items given by tagOrId don't support Text items
           interpret first and last as indices to a character, line and
           polygon items interpret them indices to a coordinate (an x,y pair).
           within the item(s) as described in "INDICES" above.  If last is
           omitted, it defaults to first.  This method returns an empty
           string.

       $canvas->delete(?tagOrId, tagOrId, ...?)
           Delete each of the items given by each tagOrId, and return an empty
           string.

       $canvas->dtag(tagOrId, ?tagToDelete?)
           For each of the items given by tagOrId, delete the tag given by
           tagToDelete from the list of those associated with the item.  If an
           item doesn't have the tag tagToDelete then the item is unaffected
           by the method.  If tagToDelete is omitted then it defaults to
           tagOrId.  This method returns an empty string.

       $canvas->find(searchCommand, ?arg, arg, ...?)
           This method returns a list consisting of all the items that meet
           the constraints specified by searchCommand and arg's.
           SearchCommand and args have any of the forms accepted by the addtag
           method.  The items are returned in stacking order, with the lowest
           item first.

       focus
       $canvas->focus(?tagOrId?)
           Set the keyboard focus for the canvas widget to the item given by
           tagOrId.  If tagOrId refers to several items, then the focus is set
           to the first such item in the display list that supports the
           insertion cursor.  If tagOrId doesn't refer to any items, or if
           none of them support the insertion cursor, then the focus isn't
           changed.  If tagOrId is an empty string, then the focus item is
           reset so that no item has the focus.  If tagOrId is not specified
           then the method returns the id for the item that currently has the
           focus, or an empty string if no item has the focus.

                   Once the focus has been set to an item, the item will
                   display the insertion cursor and all keyboard events will
                   be directed to that item.  The focus item within a canvas
                   and the focus window on the screen (set with the focus
                   method) are totally independent: a given item doesn't
                   actually have the input focus unless (a) its canvas is the
                   focus window and (b) the item is the focus item within the
                   canvas.  In most cases it is advisable to follow the focus
                   widget method with the CanvasFocus method to set the focus
                   window to the canvas (if it wasn't there already).

       $canvas->gettags(tagOrId)
           Return a list whose elements are the tags associated with the item
           given by tagOrId.  If tagOrId refers to more than one item, then
           the tags are returned from the first such item in the display list.
           If tagOrId doesn't refer to any items, or if the item contains no
           tags, then an empty string is returned.

       $canvas->icursor(tagOrId, index)
           Set the position of the insertion cursor for the item(s) given by
           tagOrId to just before the character whose position is given by
           index.  If some or all of the items given by tagOrId don't support
           an insertion cursor then this method has no effect on them.  See
           "INDICES" above for a description of the legal forms for index.
           Note:  the insertion cursor is only displayed in an item if that
           item currently has the keyboard focus (see the widget method focus,
           below), but the cursor position may be set even when the item
           doesn't have the focus.  This method returns an empty string.

       $canvas->index(tagOrId, index)
           This method returns a decimal string giving the numerical index
           within tagOrId corresponding to index.  Index gives a textual
           description of the desired position as described in "INDICES"
           above.  Text items interpret index as an index to a  character,
           line and polygon items interpret it as an index to a coordinate (an
           x,y pair).  The return value is guaranteed to lie between 0 and the
           number of characters, or coordinates, within the item, inclusive.
           If tagOrId refers to multiple items, then the index is processed in
           the first of these items that supports indexing operations (in
           display list order).

       $canvas->insert(tagOrId, beforeThis, string)
           For each of the items given by tagOrId, if the item supports text
           or coordinate, insertion then string is inserted into the item's
           text just before the character, or coordinate, whose index is
           beforeThis.  Text items interpret beforethis as an index to a
           character, line and polygon items interpret it as an index to a
           coordinate (an x,y pair).  For lines and polygons the string must
           be a valid coordinate sequence.  See "INDICES" above for
           information about the forms allowed for beforeThis.  This method
           returns an empty string.

       $canvas->itemcget(tagOrId, option)
           Returns the current value of the configuration option for the item
           given by tagOrId whose name is option.  This method is similar to
           the cget method except that it applies to a particular item rather
           than the widget as a whole.  Option may have any of the values
           accepted by the create method when the item was created.  If
           tagOrId is a tag that refers to more than one item, the first
           (lowest) such item is used.

       $canvas->itemconfigure(tagOrId, ?option?, ?value?, ?option, value,
       ...?)
           This method is similar to the configure method except that it
           modifies item-specific options for the items given by tagOrId
           instead of modifying options for the overall canvas widget.  If no
           option is specified, returns a list describing all of the available
           options for the first item given by tagOrId (see Tk::options for
           information on the format of this list).  If option is specified
           with no value, then the method returns a list describing the one
           named option (this list will be identical to the corresponding
           sublist of the value returned if no option is specified).  If one
           or more option-value pairs are specified, then the method modifies
           the given widget option(s) to have the given value(s) in each of
           the items given by tagOrId;  in this case the method returns an
           empty string.  The options and values are the same as those
           permissible in the create method when the item(s) were created; see
           the sections describing individual item types below for details on
           the legal options.

       $canvas->lower(tagOrId, ?belowThis?)
           Move all of the items given by tagOrId to a new position in the
           display list just before the item given by belowThis.  If tagOrId
           refers to more than one item then all are moved but the relative
           order of the moved items will not be changed.  BelowThis is a tag
           or id;  if it refers to more than one item then the first (lowest)
           of these items in the display list is used as the destination
           location for the moved items.  Note: this method has no effect on
           window items.  Window items always obscure other item types, and
           the stacking order of window items is determined by the raise and
           lower methods of the widget, not the raise and lower methods for
           canvases.  This method returns an empty string.

       $canvas->move(tagOrId, xAmount, yAmount)
           Move each of the items given by tagOrId in the canvas coordinate
           space by adding xAmount to the x-coordinate of each point
           associated with the item and yAmount to the y-coordinate of each
           point associated with the item.  This method returns an empty
           string.

       $canvas->postscript(?option, value, option, value, ...?)
           Generate a Postscript representation for part or all of the canvas.
           If the -file option is specified then the Postscript is written to
           a file and an empty string is returned;  otherwise the Postscript
           is returned as the result of the method.  If the interpreter that
           owns the canvas is marked as safe, the operation will fail because
           safe interpreters are not allowed to write files.  If the -channel
           option is specified, the argument denotes the name of a channel
           already opened for writing. The Postscript is written to that
           channel, and the channel is left open for further writing at the
           end of the operation.  The Postscript is created in Encapsulated
           Postscript form using version 3.0 of the Document Structuring
           Conventions.  Note: by default Postscript is only generated for
           information that appears in the canvas's window on the screen.  If
           the canvas is freshly created it may still have its initial size of
           1x1 pixel so nothing will appear in the Postscript.  To get around
           this problem either invoke the update method to wait for the canvas
           window to reach its final size, or else use the -width and -height
           options to specify the area of the canvas to print.  The
           option-value argument pairs provide additional information to
           control the generation of Postscript.  The following options are
           supported:

           -colormap => hashRef
                   HashRef must be a reference to a hash variable or an
                   anonymous hash that specifies a color mapping to use in the
                   Postscript.  Each value of the hash must consist of
                   Postscript code to set a particular color value (e.g. ``1.0
                   1.0 0.0 setrgbcolor'').  When outputting color information
                   in the Postscript, Tk checks to see if there is a key in
                   the hash with the same name as the color.  If so, Tk uses
                   the value of the element as the Postscript method to set
                   the color.  If this option hasn't been specified, or if
                   there isn't a key in hashRef for a given color, then Tk
                   uses the red, green, and blue intensities from the X color.

           -colormode => mode
                   Specifies how to output color information.  Mode must be
                   either color (for full color output), gray (convert all
                   colors to their gray-scale equivalents) or mono (convert
                   all colors to black or white).

           -file => fileName
                   Specifies the name of the file in which to write the
                   Postscript.  If this option isn't specified then the
                   Postscript is returned as the result of the method instead
                   of being written to a file.

           -fontmap => hashRef
                   HashRef must be a reference to a hash variable or an
                   anonymous hash that specifies a font mapping to use in the
                   Postscript.  Each value of the hash must consist of an
                   array reference with two elements, which are the name and
                   point size of a Postscript font.  When outputting
                   Postscript commands for a particular font, Tk checks to see
                   if hashRef contains a value with the same name as the font.
                   If there is such an element, then the font information
                   contained in that element is used in the Postscript.
                   Otherwise Tk attempts to guess what Postscript font to use.
                   Tk's guesses generally only work for well-known fonts such
                   as Times and Helvetica and Courier, and only if the X font
                   name does not omit any dashes up through the point size.
                   For example, -*-Courier-Bold-R-Normal--*-120-* will work
                   but *Courier-Bold-R-Normal*120* will not;  Tk needs the
                   dashes to parse the font name).

           -height => size
                   Specifies the height of the area of the canvas to print.
                   Defaults to the height of the canvas window.

           -pageanchor => anchor
                   Specifies which point of the printed area of the canvas
                   should appear over the positioning point on the page (which
                   is given by the -pagex and -pagey options).  For example,
                   -pageanchor=>n means that the top center of the area of the
                   canvas being printed (as it appears in the canvas window)
                   should be over the positioning point. Defaults to center.

           -pageheight => size
                   Specifies that the Postscript should be scaled in both x
                   and y so that the printed area is size high on the
                   Postscript page.  Size consists of a floating-point number
                   followed by c for centimeters, i for inches, m for
                   millimeters, or p or nothing for printer's points (1/72
                   inch).  Defaults to the height of the printed area on the
                   screen.  If both -pageheight and -pagewidth are specified
                   then the scale factor from -pagewidth is used (non-uniform
                   scaling is not implemented).

           -pagewidth => size
                   Specifies that the Postscript should be scaled in both x
                   and y so that the printed area is size wide on the
                   Postscript page.  Size has the same form as for
                   -pageheight.  Defaults to the width of the printed area on
                   the screen.  If both -pageheight and -pagewidth are
                   specified then the scale factor from -pagewidth  is used
                   (non-uniform scaling is not implemented).

           -pagex => position
                   Position gives the x-coordinate of the positioning point on
                   the Postscript page, using any of the forms allowed for
                   -pageheight.  Used in conjunction with the -pagey and
                   -pageanchor options to determine where the printed area
                   appears on the Postscript page.  Defaults to the center of
                   the page.

           -pagey => position
                   Position gives the y-coordinate of the positioning point on
                   the Postscript page, using any of the forms allowed for
                   -pageheight.  Used in conjunction with the -pagex and
                   -pageanchor options to determine where the printed area
                   appears on the Postscript page.  Defaults to the center of
                   the page.

           -rotate => boolean
                   Boolean specifies whether the printed area is to be rotated
                   90 degrees.  In non-rotated output the x-axis of the
                   printed area runs along the short dimension of the page
                   (``portrait'' orientation); in rotated output the x-axis
                   runs along the long dimension of the page (``landscape''
                   orientation).  Defaults to non-rotated.

           -width => size
                   Specifies the width of the area of the canvas to print.
                   Defaults to the width of the canvas window.

           -x => position
                   Specifies the x-coordinate of the left edge of the area of
                   the canvas that is to be printed, in canvas coordinates,
                   not window coordinates.  Defaults to the coordinate of the
                   left edge of the window.

           -y => position
                   Specifies the y-coordinate of the top edge of the area of
                   the canvas that is to be printed, in canvas coordinates,
                   not window coordinates.  Defaults to the coordinate of the
                   top edge of the window.

       $canvas->raise(tagOrId, ?aboveThis?)
           Move all of the items given by tagOrId to a new position in the
           display list just after the item given by aboveThis.  If tagOrId
           refers to more than one item then all are moved but the relative
           order of the moved items will not be changed.  AboveThis is a tag
           or id;  if it refers to more than one item then the last (topmost)
           of these items in the display list is used as the destination
           location for the moved items.  Note: this method has no effect on
           window items.  Window items always obscure other item types, and
           the stacking order of window items is determined by the raise and
           lower widget commands, not the raise and lower methods for
           canvases.  This method returns an empty string.

       $canvas->scale(tagOrId, xOrigin, yOrigin, xScale, yScale)
           Rescale all of the items given by tagOrId in canvas coordinate
           space.  XOrigin and yOrigin identify the origin for the scaling
           operation and xScale and yScale identify the scale factors for x-
           and y-coordinates, respectively (a scale factor of 1.0 implies no
           change to that coordinate).  For each of the points defining each
           item, the x-coordinate is adjusted to change the distance from
           xOrigin by a factor of xScale.  Similarly, each y-coordinate is
           adjusted to change the distance from yOrigin by a factor of yScale.
           This method returns an empty string.

       $canvas->scan(option, args)
           This method is used to implement scanning on canvases.  It has two
           forms, depending on option:

           $canvas->scanMark(x, y)
                   Records x and y and the canvas's current view;  used in
                   conjunction with later scanDragto method.  Typically this
                   method is associated with a mouse button press in the
                   widget and x and y are the coordinates of the mouse.  It
                   returns an empty string.

           $canvas->scanDragto(x, y, ?gain?.)
                   This method computes the difference between its x and y
                   arguments (which are typically mouse coordinates) and the x
                   and y arguments to the last scanMark method for the widget.
                   It then adjusts the view by 10 times the difference in
                   coordinates.  This method is typically associated It then
                   adjusts the view by gain times the difference in
                   coordinates, where gain defaults to 10.  This command is
                   typically associated with mouse motion events in the
                   widget, to produce the effect of dragging the canvas at
                   high speed through its window.  The return value is an
                   empty string.

       $canvas->select(option, ?tagOrId, arg?)
           Manipulates the selection in one of several ways, depending on
           option.  The method may take any of the forms described below.  In
           all of the descriptions below, tagOrId must refer to an item that
           supports indexing and selection;  if it refers to multiple items
           then the first of these that supports indexing and the selection is
           used.  Index gives a textual description of a position within
           tagOrId, as described in "INDICES" above.

           $canvas->selectAdjust(tagOrId, index)
                   Locate the end of the selection in tagOrId nearest to the
                   character given by index, and adjust that end of the
                   selection to be at index (i.e. including but not going
                   beyond index).  The other end of the selection is made the
                   anchor point for future selectTo method calls.  If the
                   selection isn't currently in tagOrId then this method
                   behaves the same as the selectTo widget method.  Returns an
                   empty string.

           $canvas->selectClear
                   Clear the selection if it is in this widget.  If the
                   selection isn't in this widget then the method has no
                   effect.  Returns an empty string.

           $canvas->selectFrom(tagOrId, index)
                   Set the selection anchor point for the widget to be just
                   before the character given by index in the item given by
                   tagOrId.  This method doesn't change the selection;  it
                   just sets the fixed end of the selection for future
                   selectTo method calls.  Returns an empty string.

           $canvas->selectItem
                   Returns the id of the selected item, if the selection is in
                   an item in this canvas.  If the selection is not in this
                   canvas then an empty string is returned.

           $canvas->selectTo(tagOrId, index)
                   Set the selection to consist of those characters of tagOrId
                   between the selection anchor point and index.  The new
                   selection will include the character given by index; it
                   will include the character given by the anchor point only
                   if index is greater than or equal to the anchor point.  The
                   anchor point is determined by the most recent selectAdjust
                   or selectFrom method calls for this widget.  If the
                   selection anchor point for the widget isn't currently in
                   tagOrId, then it is set to the same character given by
                   index.  Returns an empty string.

       $canvas->type(tagOrId)
           Returns the type of the item given by tagOrId, such as rectangle or
           text.  If tagOrId refers to more than one item, then the type of
           the first item in the display list is returned.  If tagOrId doesn't
           refer to any items at all then an empty string is returned.

       $canvas->xview(?args?)
           This method is used to query and change the horizontal position of
           the information displayed in the canvas's window.  It can take any
           of the following forms:

           $canvas->xview
                   Returns a list containing two elements.  Each element is a
                   real fraction between 0 and 1;  together they describe the
                   horizontal span that is visible in the window.  For
                   example, if the first element is .2 and the second element
                   is .6, 20% of the canvas's area (as defined by the
                   -scrollregion option) is off-screen to the left, the middle
                   40% is visible in the window, and 40% of the canvas is off-
                   screen to the right.  These are the same values passed to
                   scrollbars via the -xscrollcommand option.

           $canvas->xviewMoveto(fraction)
                   Adjusts the view in the window so that fraction of the
                   total width of the canvas is off-screen to the left.
                   Fraction must be a fraction between 0 and 1.

           $canvas->xviewScroll(number, what)
                   This method shifts the view in the window left or right
                   according to number and what.  Number must be an integer.
                   What must be either units or pages or an abbreviation of
                   one of these.  If what is units, the view adjusts left or
                   right in units of the xScrollIncrement option, if it is
                   greater than zero, or in units of one-tenth the window's
                   width otherwise.  If what is pages then the view adjusts in
                   units of nine-tenths the window's width.  If number is
                   negative then information farther to the left becomes
                   visible;  if it is positive then information farther to the
                   right becomes visible.

       $canvas->yview(?args?)
           This method is used to query and change the vertical position of
           the information displayed in the canvas's window.  It can take any
           of the following forms:

           $canvas->yview
                   Returns a list containing two elements.  Each element is a
                   real fraction between 0 and 1;  together they describe the
                   vertical span that is visible in the window.  For example,
                   if the first element is .6 and the second element is 1.0,
                   the lowest 40% of the canvas's area (as defined by the
                   -scrollregion option) is visible in the window.  These are
                   the same values passed to scrollbars via the
                   -yscrollcommand option.

           $canvas->yviewMoveto(fraction)
                   Adjusts the view in the window so that fraction of the
                   canvas's area is off-screen to the top.  Fraction is a
                   fraction between 0 and 1.

           $canvas->yviewScroll(number, what)
                   This method adjusts the view in the window up or down
                   according to number and what.  Number must be an integer.
                   What must be either units or pages.  If what is units, the
                   view adjusts up or down in units of the yScrollIncrement
                   option, if it is greater than zero, or in units of one-
                   tenth the window's height otherwise.  If what is pages then
                   the view adjusts in units of nine-tenths the window's
                   height.  If number is negative then higher information
                   becomes visible;  if it is positive then lower information
                   becomes visible.


OVERVIEW OF ITEM TYPES

       The sections below describe the various types of items supported by
       canvas widgets.  Each item type is characterized by two things: first,
       the form of the create method used to create instances of the type;
       and second, a set of configuration options for items of that type,
       which may be used in the create and itemconfigure methods.  Most items
       don't support indexing or selection or the methods related to them,
       such as index and insert.  Where items do support these facilities, it
       is noted explicitly in the descriptions below.  At present, text, line
       and polygon items provide this support.  For lines and polygons the
       indexing facility is used to manipulate the coordinates of the item.


ARC ITEMS

       Items of type arc appear on the display as arc-shaped regions.  An arc
       is a section of an oval delimited by two angles (specified by the
       -start and -extent options) and displayed in one of several ways
       (specified by the -style option).  Arcs are created with methods of the
       following form:

        $canvas->createArc(x1, y1, x2, y2, ?option, value, option, value, ...?)

       The arguments x1, y1, x2, and y2 give the coordinates of two diagonally
       opposite corners of a rectangular region enclosing the oval that
       defines the arc.  After the coordinates there may be any number of
       option-value pairs, each of which sets one of the configuration options
       for the item.  These same option-value pairs may be used in
       itemconfigure methods to change the item's configuration.  The
       following options are supported for arcs:

       -dash => pattern
       -activedash => pattern
       -disableddash => pattern
           This option specifies dash patterns for the normal state, the
           active state, and the disabled state of an arc item.  pattern may
           have any of the forms accepted by Tk_GetDash.  If the dash options
           are omitted then the default is a solid outline.

       -dashoffset => offset
           The starting offset into the pattern provided by the -dash option.
           -dashoffset is ignored if there is no -dash pattern.

       -extent => degrees
           Specifies the size of the angular range occupied by the arc.  The
           arc's range extends for degrees degrees counter-clockwise from the
           starting angle given by the -start option.  Degrees may be
           negative.  If it is greater than 360 or less than -360, then
           degrees modulo 360 is used as the extent.

       -fill => color
       -activefill => color
       -disabledfill => color
           Specifies the color to be used to fill the arc region in its
           normal, active, and disabled states, Color may have any of the
           forms accepted by Tk_GetColor.  If color is an empty string (the
           default), then then the arc will not be filled.

       -outline => color
       -activeoutline => color
       -disabledoutline => color
           This option specifies the color that should be used to draw the
           outline of the arc in its normal, active and disabled states.
           Color may have any of the forms accepted by Tk_GetColor.  This
           option defaults to black.  If color is specified as undef then no
           outline is drawn for the arc.

       -outlinestipple => bitmap
       -activeoutlinestipple => bitmap
       -disabledoutlinestipple => bitmap
           This option specifies stipple patterns that should be used to draw
           the outline of the arc in its normal, active and disabled states.
           Indicates that the outline for the arc should be drawn with a
           stipple pattern; bitmap specifies the stipple pattern to use, in
           any of the forms accepted by Tk_GetBitmap.  If the -outline option
           hasn't been specified then this option has no effect.  If bitmap is
           an empty string (the default), then the outline is drawn in a solid
           fashion.

       -start => degrees
           Specifies the beginning of the angular range occupied by the arc.
           Degrees is given in units of degrees measured counter-clockwise
           from the 3-o'clock position;  it may be either positive or
           negative.

       -state => state
           Modifies the state of the arc item where state may be set to one
           of: normal, disabled, hidden or "". If set to empty, the state of
           the canvas itself is used. An arc item may also be in the "active"
           state if the mouse is currently over it.  Many options can take
           separate specifications in normal, active and disabled states such
           that the appearance of the item can be different in each state.

       -stipple => bitmap
       -activestipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to fill
           the the arc in its normal, active and disabled states.  bitmap
           specifies the stipple pattern to use, in any of the forms accepted
           by Tk_GetBitmap.  If the -fill option hasn't been specified then
           this option has no effect.  If bitmap is an empty string (the
           default), then filling is done in a solid fashion.

       -style => type
           Specifies how to draw the arc.  If type is pieslice (the default)
           then the arc's region is defined by a section of the oval's
           perimeter plus two line segments, one between the center of the
           oval and each end of the perimeter section.  If type is chord then
           the arc's region is defined by a section of the oval's perimeter
           plus a single line segment connecting the two end points of the
           perimeter section.  If type is arc then the arc's region consists
           of a section of the perimeter alone.  In this last case the -fill
           option is ignored.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the arc item
           is updated on the screen.

       -width => outlineWidth
       -activewidth => outlineWidth
       -disabledwidth => outlineWidth
           Specifies the width of the outline to be drawn around the arc's
           region, in its normal, active and disabled states.  outlineWidth
           may be in any of the forms described in the "COORDINATES" section
           above.  If the -outline option has been specified as undef then
           this option has no effect.  Wide outlines will be drawn centered on
           the edges of the arc's region.  This option defaults to 1.0.


BITMAP ITEMS

       Items of type bitmap appear on the display as images with two colors,
       foreground and background.  Bitmaps are created with methods of the
       following form:

        $canvas->createBitmap(x, y, ?option, value, option, value, ...?)

       The arguments x and y specify the coordinates of a point used to
       position the bitmap on the display (see the -anchor option below for
       more information on how bitmaps are displayed).  After the coordinates
       there may be any number of option-value pairs, each of which sets one
       of the configuration options for the item.  These same option-value
       pairs may be used in itemconfigure methods to change the item's
       configuration.  The following options are supported for bitmaps:

       -anchor => anchorPos
           AnchorPos tells how to position the bitmap relative to the
           positioning point for the item;  it may have any of the forms
           accepted by Tk_GetAnchor.  For example, if anchorPos is center then
           the bitmap is centered on the point;  if anchorPos is n then the
           bitmap will be drawn so that its top center point is at the
           positioning point.  This option defaults to center.

       -background => color
       -activebackground => color
       -disabledbackground => color
           Specifies the color to use for each of the bitmap's '0' valued
           pixels in its normal, active and disabled states.  Color may have
           any of the forms accepted by Tk_GetColor.  If this option isn't
           specified, or if it is specified as undef, then nothing is
           displayed where the bitmap pixels are 0;  this produces a
           transparent effect.

       -bitmap => bitmap
       -activebitmap => bitmap
       -disabledbitmap => bitmap
           Specifies the bitmaps to display in the item in its normal, active
           and disabled states. All bitmaps must have the same width and
           height.  Bitmap may have any of the forms accepted by Tk_GetBitmap.

       -foreground => color
       -activeforeground => color
       -disabledforeground => color
           Specifies the color to use for each of the bitmap's '1' valued
           pixels in its normal, active and disabled states.  Color may have
           any of the forms accepted by Tk_GetColor and defaults to black.

       -state => state
           Modifies the state of the bitmap item where state may be set to one
           of: normal, disabled, or hidden.  An bitmap item may also be in the
           "active" state if the mouse is currently over it.  Many options can
           take separate specifications in normal, active and disabled states
           such that the appearance of the item can be different in each
           state.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the bitmap
           item is updated on the screen.


GRID ITEMS

       Items of type grid are intended for producing a visual reference for
       interpreting other items. They can be drawn as either lines (with dash
       style) or as rectangular "dots" at each grid point.

       Items of type grid are unlike other items they always cover the whole
       of the canvas, but are never enclosed by nor overlap any area and are
       not near any point. That is they are intended to be always visible but
       not "pickable", as such they do support the "active" state.  They are
       like other items in that: multiple grids are permitted, they can be
       raised and lowered relative to other items, they can be moved and
       scaled. As yet grids do not appear in PostScript output.

       Grids have outline like configure options. Grids are created with
       methods of the following form:

        $canvas->createGrid(x1, y1, x2, y2, ?option, value, option, value, ...?)

       The arguments x1, y1 give the origin of the grid. x2, and y2 give the
       coordinates of the next grid point in their respective directions.
       After the coordinates there may be any number of option-value pairs,
       each of which sets one of the configuration options for the item.
       These same option-value pairs may be used in itemconfigure methods to
       change the item's configuration.

       The following options are supported for grids:

       -lines => boolean
           If -lines is set to a true value then lines are drawn for both X
           and Y grids in the style determined by -dash. Otherwise retangular
           "dots" are drawn at each grid point.

       -dash => pattern
       -disableddash => pattern
           This option specifies dash patterns for the normal state, and the
           disabled state of a grid item.  pattern may have any of the forms
           accepted by Tk_GetDash.  If the dash options are omitted then the
           default is a solid outline.

       -dashoffset => offset
           The starting offset into the pattern provided by the -dash option.
           -dashoffset is ignored if there is no -dash pattern.

       -color => color
       -disabledcolor => color
           This option specifies the color that should be used to draw the
           outline of the grid in its normal and disabled states.  Color may
           have any of the forms accepted by Tk_GetColor.  This option
           defaults to black.  If color is undef then no grid will be drawn.

       -stipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to draw
           the outline of the rectangle in its normal and disabled states.
           bitmap specifies the stipple pattern to use, in any of the forms
           accepted by Tk_GetBitmap.  If bitmap is an empty string (the
           default), then the outline is drawn in a solid fashion.

       -state => state
           Modifies the state of the rectangle item where state may be set to
           one of: normal, disabled, or hidden. Many options can take separate
           specifications in normal and disabled states such that the
           appearance of the item can be different in each state.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the grid
           item is updated on the screen.

       -width => outlineWidth
       -disabledwidth => outlineWidth
           Specifies the width of the lines drawn by the grid or the size (in
           both X and Y) of the dots, in its normal and disabled states.  This
           option defaults to 1.0.


IMAGE ITEMS

       Items of type image are used to display images on a canvas.  Images are
       created with methods of the following form:

        $canvas->createImage(x, y, ?option, value, option, value, ...?)

       The arguments x and y specify the coordinates of a point used to
       position the image on the display (see the -anchor option below for
       more information).  After the coordinates there may be any number of
       option-value pairs, each of which sets one of the configuration options
       for the item.  These same option-value pairs may be used in
       itemconfigure methods to change the item's configuration.  The
       following options are supported for images:

       -anchor => anchorPos
           AnchorPos tells how to position the image relative to the
           positioning point for the item;  it may have any of the forms
           accepted by Tk_GetAnchor.  For example, if anchorPos is center then
           the image is centered on the point;  if anchorPos is n then the
           image will be drawn so that its top center point is at the
           positioning point.  This option defaults to center.

       -image => name
       -activeimage => name
       -disabledimage => name
           Specifies the name of the images to display in the item in is
           normal, active and disabled states. This image must have been
           created previously, see Tk::Image.

       -state => state
           Modifies the state of the image item where state may be set to one
           of: normal, disabled, or hidden.  An image item may also be in the
           "active" state if the mouse is currently over it.  Many options can
           take separate specifications in normal, active and disabled states
           such that the appearance of the item can be different in each
           state.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item;
           it may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the image
           item is updated on the screen.


LINE ITEMS

       Items of type line appear on the display as one or more connected line
       segments or curves.  Line items support coordinate indexing operations
       using the canvas methods: dchars, index, insert.  Lines are created
       with methods of the following form:

        $canvas->createLine(x1, y1..., xn, yn, ?option, value, option, value, ...?)

       The arguments x1 through yn give the coordinates for a series of two or
       more points that describe a series of connected line segments.  After
       the coordinates there may be any number of option-value pairs, each of
       which sets one of the configuration options for the item.  These same
       option-value pairs may be used in itemconfigure methods to change the
       item's configuration.  The following options are supported for lines:

       -arrow => where
           Indicates whether or not arrowheads are to be drawn at one or both
           ends of the line.  Where must have one of the values none (for no
           arrowheads), first (for an arrowhead at the first point of the
           line), last (for an arrowhead at the last point of the line), or
           both (for arrowheads at both ends).  This option defaults to none.

       -arrowshape => shape
           This option indicates how to draw arrowheads.  The shape argument
           must be a list with three elements, each specifying a distance in
           any of the forms described in the "COORDINATES" section above.  The
           first element of the list gives the distance along the line from
           the neck of the arrowhead to its tip.  The second element gives the
           distance along the line from the trailing points of the arrowhead
           to the tip, and the third element gives the distance from the
           outside edge of the line to the trailing points.  If this option
           isn't specified then Tk picks a ``reasonable'' shape.

       -capstyle => style
           Specifies the ways in which caps are to be drawn at the endpoints
           of the line.  Style may have any of the forms accepted by
           Tk_GetCapStyle (butt, projecting, or round).  If this option isn't
           specified then it defaults to butt.  Where arrowheads are drawn the
           cap style is ignored.

       -dash => pattern
       -activedash => pattern
       -disableddash => pattern
           This option specifies dash patterns for the normal state, the
           active state, and the disabled state of a line item.  pattern may
           have any of the forms accepted by Tk_GetDash.  If the dash options
           are omitted then the default is a solid outline.

       -dashoffset => offset
           The starting offset into the pattern provided by the -dash option.
           -dashoffset is ignored if there is no -dash pattern.

       -fill => color
       -activefill => color
       -disabledfill => color
           Specifies the color to be used to fill the line in its normal,
           active, and disabled states.  Color may have any of the forms
           acceptable to Tk_GetColor.  It may also be undef, in which case the
           line will be transparent.  This option defaults to black.

       -joinstyle => style
           Specifies the ways in which joints are to be drawn at the vertices
           of the line.  Style may have any of the forms accepted by
           Tk_GetCapStyle (bevel, miter, or round).  If this option isn't
           specified then it defaults to miter.  If the line only contains two
           points then this option is irrelevant.

       -smooth => boolean
           Boolean must have one of the forms accepted by Tk_GetBoolean.  It
           indicates whether or not the line should be drawn as a curve.  If
           so, the line is rendered as a set of parabolic splines: one spline
           is drawn for the first and second line segments, one for the second
           and third, and so on.  Straight-line segments can be generated
           within a curve by duplicating the end-points of the desired line
           segment.

       -splinesteps => number
           Specifies the degree of smoothness desired for curves:  each spline
           will be approximated with number line segments.  This option is
           ignored unless the -smooth option is true.

       -state => state
           Modifies the state of the line item where state may be set to one
           of: normal, disabled, or hidden.  A line item may also be in the
           "active" state if the mouse is currently over it.  Many options can
           take separate specifications in normal, active and disabled states
           such that the appearance of the item can be different in each
           state.

       -stipple => bitmap
       -activestipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to fill
           the the line in its normal, active and disabled states.  bitmap
           specifies the stipple pattern to use, in any of the forms accepted
           by Tk_GetBitmap.  If bitmap is an empty string (the default), then
           filling is done in a solid fashion.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the line
           item is updated on the screen.

       -width => lineWidth
       -activewidth => lineWidth
       -disabledwidth => lineWidth
           Specifies the width of the line in its normal, active and disabled
           states.  lineWidth may be in any of the forms described in the
           "COORDINATES" section above.

           Wide lines will be drawn centered on the path specified by the
           points.  If this option isn't specified then it defaults to 1.0.


OVAL ITEMS

       Items of type oval appear as circular or oval regions on the display.
       Each oval may have an outline, a fill, or both.  Ovals are created with
       methods of the following form:

        $canvas->createOval(x1, y1, x2, y2, ?option, value, option, value, ...?)

       The arguments x1, y1, x2, and y2 give the coordinates of two diagonally
       opposite corners of a rectangular region enclosing the oval.  The oval
       will include the top and left edges of the rectangle not the lower or
       right edges.  If the region is square then the resulting oval is
       circular; otherwise it is elongated in shape.  After the coordinates
       there may be any number of option-value pairs, each of which sets one
       of the configuration options for the item.  These same option-value
       pairs may be used in itemconfigure methods to change the item's
       configuration.  The following options are supported for ovals:

       -dash => pattern
       -activedash => pattern
       -disableddash => pattern
           This option specifies dash patterns for the normal state, the
           active state, and the disabled state of an oval item.  pattern may
           have any of the forms accepted by Tk_GetDash.  If the dash options
           are omitted then the default is a solid outline.

       -dashoffset => offset
           The starting offset into the pattern provided by the -dash option.
           -dashoffset is ignored if there is no -dash pattern.

       -fill => color
       -activefill => color
       -disabledfill => color
           Specifies the color to be used to fill the oval in its normal,
           active, and disabled states.  Color may have any of the forms
           accepted by Tk_GetColor.  If color is undef (the default), then
           then the oval will not be filled.

       -outline => color
       -activeoutline => color
       -disabledoutline => color
           This option specifies the color that should be used to draw the
           outline of the oval in its normal, active and disabled states.
           Color may have any of the forms accepted by Tk_GetColor.  This
           option defaults to black.  If color is undef then no outline will
           be drawn for the oval.

       -outlinestipple => bitmap
       -activeoutlinestipple => bitmap
       -disabledoutlinestipple => bitmap
           This option specifies stipple patterns that should be used to draw
           the outline of the oval in its normal, active and disabled states.
           bitmap specifies the stipple pattern to use, in any of the forms
           accepted by Tk_GetBitmap.  If the -outline option hasn't been
           specified then this option has no effect.  If bitmap is an empty
           string (the default), then the outline is drawn in a solid fashion.

       -state => state
           Modifies the state of the oval item where state may be set to one
           of: normal, disabled, or hidden.  An oval item may also be in the
           "active" state if the mouse is currently over it.  Many options can
           take separate specifications in normal, active and disabled states
           such that the appearance of the item can be different in each
           state.

       -stipple => bitmap
       -activestipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to fill
           the the oval in its normal, active and disabled states.  bitmap
           specifies the stipple pattern to use, in any of the forms accepted
           by Tk_GetBitmap.  If the -fill option hasn't been specified then
           this option has no effect.  If bitmap is an empty string (the
           default), then filling is done in a solid fashion.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the oval
           item is updated on the screen.

       -width => outlineWidth
       -activewidth => outlineWidth
       -disabledwidth => outlineWidth
           Specifies the width of the outline to be drawn around the oval, in
           its normal, active and disabled states.  outlineWidth specifies the
           width of the outline to be drawn around the oval, in any of the
           forms described in the "COORDINATES" section above.

           If the -outline option hasn't been specified then this option has
           no effect.  Wide outlines are drawn centered on the oval path
           defined by x1, y1, x2, and y2.  This option defaults to 1.0.


POLYGON ITEMS

       Items of type polygon appear as polygonal or curved filled regions on
       the display.  Polygon items support coordinate indexing operations
       using the canvas methods: dchars, index, insert.  Polygons are created
       with methods of the following form:

        $canvas->createPolygon(x1, y1, ..., xn, yn, ?option, value, option, value, ...?)

       The arguments x1 through yn specify the coordinates for three or more
       points that define a closed polygon.  The first and last points may be
       the same;  whether they are or not, Tk will draw the polygon as a
       closed polygon.  After the coordinates there may be any number of
       option-value pairs, each of which sets one of the configuration options
       for the item.  These same option-value pairs may be used in
       itemconfigure methods to change the item's configuration.  The
       following options are supported for polygons:

       -dash => pattern
       -activedash => pattern
       -disableddash => pattern
           This option specifies dash patterns for the normal state, the
           active state, and the disabled state of an polygon item.  pattern
           may have any of the forms accepted by Tk_GetDash.  If the dash
           options are omitted then the default is a solid outline.

       -dashoffset => offset
           The starting offset into the pattern provided by the -dash option.
           -dashoffset is ignored if there is no -dash pattern.

       -fill => color
       -activefill => color
       -disabledfill => color
           Specifies the color to be used to fill the polygon in its normal,
           active, and disabled states.  Color may have any of the forms
           acceptable to Tk_GetColor.  If color is undef then the polygon will
           be transparent.  This option defaults to black.

       -joinstyle => style
           Specifies the ways in which joints are to be drawn at the vertices
           of the outline.  Style may have any of the forms accepted by
           Tk_GetCapStyle (bevel, miter, or round).  If this option isn't
           specified then it defaults to miter.

       -outline => color
       -activeoutline => color
       -disabledoutline => color
           This option specifies the color that should be used to draw the
           outline of the polygon in its normal, active and disabled states.
           Color may have any of the forms accepted by Tk_GetColor.  If color
           is undef then no outline will be drawn for the polygon.  This
           option defaults to undef (no outline).

       -outlinestipple => bitmap
       -activeoutlinestipple => bitmap
       -disabledoutlinestipple => bitmap
           This option specifies stipple patterns that should be used to draw
           the outline of the polygon in its normal, active and disabled
           states.  bitmap specifies the stipple pattern to use, in any of the
           forms accepted by Tk_GetBitmap.  If the -outline option hasn't been
           specified then this option has no effect.  If bitmap is an empty
           string (the default), then the outline is drawn in a solid fashion.

       -smooth => boolean
           Boolean must have one of the forms accepted by Tk_GetBoolean It
           indicates whether or not the polygon should be drawn with a curved
           perimeter.  If so, the outline of the polygon becomes a set of
           parabolic splines, one spline for the first and second line
           segments, one for the second and third, and so on.  Straight-line
           segments can be generated in a smoothed polygon by duplicating the
           end-points of the desired line segment.

       -splinesteps => number
           Specifies the degree of smoothness desired for curves:  each spline
           will be approximated with number line segments.  This option is
           ignored unless the -smooth option is true.

       -state => state
           Modifies the state of the polygon item where state may be set to
           one of: normal, disabled, or hidden.  A polygon item may also be in
           the "active" state if the mouse is currently over it.  Many options
           can take separate specifications in normal, active and disabled
           states such that the appearance of the item can be different in
           each state.

       -stipple => bitmap
       -activestipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to fill
           the the polygon in its normal, active and disabled states.  bitmap
           specifies the stipple pattern to use, in any of the forms accepted
           by Tk_GetBitmap.  If bitmap is an empty string (the default), then
           filling is done in a solid fashion.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the polygon
           item is updated on the screen.

       -width => outlineWidth
       -activewidth => outlineWidth
       -disabledwidth => outlineWidth
       Specifies the width of the outline to be drawn around
           the polygon, in its normal, active and disabled states.
           outlineWidth may be in any of the forms described in the
           COORDINATES section above.  OutlineWidth specifies the width of the
           outline to be drawn around the polygon, in any of the forms
           described in the "COORDINATES" section above.  If the -outline
           option hasn't been specified then this option has no effect.  This
           option defaults to 1.0.

           Polygon items are different from other items such as rectangles,
           ovals and arcs in that interior points are considered to be
           ``inside'' a polygon (e.g. for purposes of the find closest and
           find overlapping methods) even if it is not filled.  For most other
           item types, an interior point is considered to be inside the item
           only if the item is filled or if it has neither a fill nor an
           outline.  If you would like an unfilled polygon whose interior
           points are not considered to be inside the polygon, use a line item
           instead.


RECTANGLE ITEMS

       Items of type rectangle appear as rectangular regions on the display.
       Each rectangle may have an outline, a fill, or both.  Rectangles are
       created with methods of the following form:

        $canvas->createRectangle(x1, y1, x2, y2, ?option, value, option, value, ...?)

       The arguments x1, y1, x2, and y2 give the coordinates of two diagonally
       opposite corners of the rectangle (the rectangle will include its upper
       and left edges but not its lower or right edges).  After the
       coordinates there may be any number of option-value pairs, each of
       which sets one of the configuration options for the item.  These same
       option-value pairs may be used in itemconfigure methods to change the
       item's configuration.  The following options are supported for
       rectangles:

       -dash => pattern
       -activedash => pattern
       -disableddash => pattern
           This option specifies dash patterns for the normal state, the
           active state, and the disabled state of a rectangle item.  pattern
           may have any of the forms accepted by Tk_GetDash.  If the dash
           options are omitted then the default is a solid outline.

       -dashoffset => offset
           The starting offset into the pattern provided by the -dash option.
           -dashoffset is ignored if there is no -dash pattern.

       -fill => color
       -activefill => color
       -disabledfill => color
           Specifies the color to be used to fill the rectangle in its normal,
           active, and disabled states.  Color may be specified in any of the
           forms accepted by Tk_GetColor.  If color is undef (the default),
           then the rectangle will not be filled.

       -outline => color
       -activeoutline => color
       -disabledoutline => color
           This option specifies the color that should be used to draw the
           outline of the rectangle in its normal, active and disabled states.
           Color may have any of the forms accepted by Tk_GetColor.  This
           option defaults to black.  If color is undef then no outline will
           be drawn for the rectangle.

       -outlinestipple => bitmap
       -activeoutlinestipple => bitmap
       -disabledoutlinestipple => bitmap
           This option specifies stipple patterns that should be used to draw
           the outline of the rectangle in its normal, active and disabled
           states.  bitmap specifies the stipple pattern to use, in any of the
           forms accepted by Tk_GetBitmap.  If the -outline option hasn't been
           specified then this option has no effect.  If bitmap is an empty
           string (the default), then the outline is drawn in a solid fashion.

       -state => state
           Modifies the state of the rectangle item where state may be set to
           one of: normal, disabled, or hidden.  A rectangle item may also be
           in the "active" state if the mouse is currently over it.  Many
           options can take separate specifications in normal, active and
           disabled states such that the appearance of the item can be
           different in each state.

       -stipple => bitmap
       -activestipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to fill
           the the rectangle in its normal, active and disabled states.
           bitmap specifies the stipple pattern to use, in any of the forms
           accepted by Tk_GetBitmap.  If the -fill option hasn't been
           specified then this option has no effect.  If bitmap is an empty
           string (the default), then filling is done in a solid fashion.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the
           rectangle item is updated on the screen.

       -width => outlineWidth
       -activewidth => outlineWidth
       -disabledwidth => outlineWidth
           Specifies the width of the outline to be drawn around the
           rectangle, in its normal, active and disabled states.  OutlineWidth
           specifies the width of the outline to be drawn around the
           rectangle, in any of the forms described in the "COORDINATES"
           section above.

           If the -outline option hasn't been specified then this option has
           no effect.  Wide outlines are drawn centered on the rectangular
           path defined by x1, y1, x2, and y2.  This option defaults to 1.0.


TEXT ITEMS

       A text item displays a string of characters on the screen in one or
       more lines.  Text items support indexing and selection, along with the
       following text-related canvas methods:  dchars, focus, icursor, index,
       insert, select.  Text items are created with methods of the following
       form:

        $canvas->createText(x, y, ?option, value, option, value, ...?)

       The arguments x and y specify the coordinates of a point used to
       position the text on the display (see the options below for more
       information on how text is displayed).  After the coordinates there may
       be any number of option-value pairs, each of which sets one of the
       configuration options for the item.  These same option-value pairs may
       be used in itemconfigure methods to change the item's configuration.
       The following options are supported for text items:

       -anchor => anchorPos
           AnchorPos tells how to position the text relative to the
           positioning point for the text;  it may have any of the forms
           accepted by Tk_GetAnchor.  For example, if anchorPos is center then
           the text is centered on the point;  if anchorPos is n then the text
           will be drawn such that the top center point of the rectangular
           region occupied by the text will be at the positioning point.  This
           option defaults to center.

       -fill => color
       -activefill => color
       -disabledfill => color
           Specifies the color to be used to fill the text in its normal,
           active, and disabled states.  Color may have any of the forms
           accepted by Tk_GetColor.  If color is undef then the text will be
           transparent.  If this option isn't specified then it defaults to
           black.

       -font => fontName
           Specifies the font to use for the text item.  FontName may be any
           string acceptable to Tk_GetFontStruct.  If this option isn't
           specified, it defaults to a system-dependent font.

       -justify => how
           Specifies how to justify the text within its bounding region.  How
           must be one of the values left, right, or center.  This option will
           only matter if the text is displayed as multiple lines.  If the
           option is omitted, it defaults to left.

       -state => state
           Modifies the state of the text item where state may be set to one
           of: normal, disabled, or hidden.  A text item may also be in the
           "active" state if the mouse is currently over it.  Many options can
           take separate specifications in normal, active and disabled states
           such that the appearance of the item can be different in each
           state.

       -stipple => bitmap
       -activestipple => bitmap
       -disabledstipple => bitmap
           This option specifies stipple patterns that should be used to fill
           the the text in its normal, active and disabled states.  bitmap
           specifies the stipple pattern to use, in any of the forms accepted
           by Tk_GetBitmap.  If bitmap is an empty string (the default) then
           the text is drawn in a solid fashion.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -text => string
           String specifies the characters to be displayed in the text item.
           Newline characters cause line breaks.  The characters in the item
           may also be changed with the insert and delete methods.  This
           option defaults to an empty string.

       -updatecommand => command
           Specifies a callback that is to be executed every time the text
           item is updated on the screen.

       -width => lineLength
           Specifies a maximum line length for the text, in any of the forms
           described in the "COORDINATES" section above.  If this option is
           zero (the default) the text is broken into lines only at newline
           characters.  However, if this option is non-zero then any line that
           would be longer than lineLength is broken just before a space
           character to make the line shorter than lineLength;  the space
           character is treated as if it were a newline character.


WINDOW ITEMS

       Items of type window cause a particular window to be displayed at a
       given position on the canvas.  Window items are created with methods of
       the following form:

           $canvas->createWindow(x, y?, -option=>value, -option=>value, ...?)

       The arguments x and y specify the coordinates of a point used to
       position the window on the display (see the -anchor option below for
       more information on how bitmaps are displayed).  After the coordinates
       there may be any number of option-value pairs, each of which sets one
       of the configuration options for the item.  These same option-value
       pairs may be used in itemconfigure method to change the item's
       configuration.  The following options are supported for window items:

       -anchor => anchorPos
           AnchorPos tells how to position the window relative to the
           positioning point for the item;  it may have any of the forms
           accepted by Tk_GetAnchor.  For example, if anchorPos is center then
           the window is centered on the point;  if anchorPos is n then the
           window will be drawn so that its top center point is at the
           positioning point.  This option defaults to center.

       -height => pixels
           Specifies the height to assign to the item's window.  Pixels may
           have any of the forms described in the "COORDINATES" section above.
           If this option isn't specified, or if it is specified as an empty
           string, then the window is given whatever height it requests
           internally.

       -state => state
           Modifies the state of the window item where state may be set to one
           of: normal, disabled, or hidden.

       -tags => tagList
           Specifies a set of tags to apply to the item.  TagList consists of
           a list of tag names, which replace any existing tags for the item.
           TagList may be an empty list.

       -updatecommand => command
           Specifies a callback that is to be executed every time the window
           item is updated on the screen.

       -width => pixels
           Specifies the width to assign to the item's window.  Pixels may
           have any of the forms described in the "COORDINATES" section above.
           If this option isn't specified, or if it is specified as an empty
           string, then the window is given whatever width it requests
           internally.

       -window => $widget
           Specifies the window to associate with this item.  The window
           specified by $widget must either be a child of the canvas widget or
           a child of some ancestor of the canvas widget.  PathName may not
           refer to a top-level window.

           Note:  due to restrictions in the ways that windows are managed, it
           is not possible to draw other graphical items (such as lines and
           images) on top of window items.  A window item always obscures any
           graphics that overlap it, regardless of their order in the display
           list.


APPLICATION-DEFINED ITEM TYPES

       It is possible for individual applications to define new item types for
       canvas widgets using C code.  See the documentation for
       Tk_CreateItemType.


BINDINGS

       Canvas has default bindings to allow scrolling if necessary: <Up>,
       <Down>, <Left> and <Right> (and their <Control-*> counter parts).
       Further <Proir>, <Next>, <Home> and <End>.  These bindings allow you to
       navigate the same way as in other widgets that can scroll.


Perl/Tk Methods

       The following methods are added as perl code:

       $canvas->get_corners
           Returns the bounding box in Canvas coordinates of the visible
           portion of the Canvas. (Written by Slaven Rezic.)


CREDITS

       Tk's canvas widget is a blatant ripoff of ideas from Joel Bartlett's
       ezd program.  Ezd provides structured graphics in a Scheme environment
       and preceded canvases by a year or two.  Its simple mechanisms for
       placing and animating graphical objects inspired the functions of
       canvases.


KEYWORDS

       canvas, widget



perl v5.18.0                      2012-01-16                         Canvas(3)

perl-Tk 804.030_502 - Generated Mon Aug 12 14:38:20 CDT 2013
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