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GtkCellAreaContextGtkCellAreaContext — Stores geometrical information for a series of rows in a GtkCellArea |
Functions
Properties
| GtkCellArea * | area | Read / Write / Construct Only |
| gint | minimum-height | Read |
| gint | minimum-width | Read |
| gint | natural-height | Read |
| gint | natural-width | Read |
Description
The GtkCellAreaContext object is created by a given GtkCellArea
implementation via its GtkCellAreaClass.create_context() virtual
method and is used to store cell sizes and alignments for a series of
GtkTreeModel rows that are requested and rendered in the same context.
GtkCellLayout widgets can create any number of contexts in which to
request and render groups of data rows. However, it’s important that the
same context which was used to request sizes for a given GtkTreeModel
row also be used for the same row when calling other GtkCellArea APIs
such as gtk_cell_area_render() and gtk_cell_area_event().
Functions
gtk_cell_area_context_get_area ()
GtkCellArea *
gtk_cell_area_context_get_area (GtkCellAreaContext *context);
Fetches the GtkCellArea this context
was created by.
This is generally unneeded by layouting widgets; however, it is important for the context implementation itself to fetch information about the area it is being used for.
For instance at GtkCellAreaContextClass.allocate() time
it’s important to know details about any cell spacing
that the GtkCellArea is configured with in order to
compute a proper allocation.
Since 3.0
gtk_cell_area_context_allocate ()
void gtk_cell_area_context_allocate (GtkCellAreaContext *context,gint width,gint height);
Allocates a width and/or a height for all rows which are to be
rendered with context
.
Usually allocation is performed only horizontally or sometimes vertically since a group of rows are usually rendered side by side vertically or horizontally and share either the same width or the same height. Sometimes they are allocated in both horizontal and vertical orientations producing a homogeneous effect of the rows. This is generally the case for GtkTreeView when “fixed-height-mode” is enabled.
Since 3.0
Parameters
context |
||
width |
the allocated width for all GtkTreeModel rows rendered
with |
|
height |
the allocated height for all GtkTreeModel rows rendered
with |
gtk_cell_area_context_reset ()
void
gtk_cell_area_context_reset (GtkCellAreaContext *context);
Resets any previously cached request and allocation data.
When underlying GtkTreeModel data changes its
important to reset the context if the content
size is allowed to shrink. If the content size
is only allowed to grow (this is usually an option
for views rendering large data stores as a measure
of optimization), then only the row that changed
or was inserted needs to be (re)requested with
gtk_cell_area_get_preferred_width().
When the new overall size of the context requires that the allocated size changes (or whenever this allocation changes at all), the variable row sizes need to be re-requested for every row.
For instance, if the rows are displayed all with
the same width from top to bottom then a change
in the allocated width necessitates a recalculation
of all the displayed row heights using
gtk_cell_area_get_preferred_height_for_width().
Since 3.0
gtk_cell_area_context_get_preferred_width ()
void gtk_cell_area_context_get_preferred_width (GtkCellAreaContext *context,gint *minimum_width,gint *natural_width);
Gets the accumulative preferred width for all rows which have been requested with this context.
After gtk_cell_area_context_reset() is called and/or before ever
requesting the size of a GtkCellArea, the returned values are 0.
Parameters
Since 3.0
gtk_cell_area_context_get_preferred_height ()
void gtk_cell_area_context_get_preferred_height (GtkCellAreaContext *context,gint *minimum_height,gint *natural_height);
Gets the accumulative preferred height for all rows which have been requested with this context.
After gtk_cell_area_context_reset() is called and/or before ever
requesting the size of a GtkCellArea, the returned values are 0.
Parameters
Since 3.0
gtk_cell_area_context_get_preferred_height_for_width ()
void gtk_cell_area_context_get_preferred_height_for_width (GtkCellAreaContext *context,gint width,gint *minimum_height,gint *natural_height);
Gets the accumulative preferred height for width
for all rows
which have been requested for the same said width
with this context.
After gtk_cell_area_context_reset() is called and/or before ever
requesting the size of a GtkCellArea, the returned values are -1.
Parameters
Since 3.0
gtk_cell_area_context_get_preferred_width_for_height ()
void gtk_cell_area_context_get_preferred_width_for_height (GtkCellAreaContext *context,gint height,gint *minimum_width,gint *natural_width);
Gets the accumulative preferred width for height
for all rows which
have been requested for the same said height
with this context.
After gtk_cell_area_context_reset() is called and/or before ever
requesting the size of a GtkCellArea, the returned values are -1.
Parameters
Since 3.0
gtk_cell_area_context_get_allocation ()
void gtk_cell_area_context_get_allocation (GtkCellAreaContext *context,gint *width,gint *height);
Fetches the current allocation size for context
.
If the context was not allocated in width or height, or if the
context was recently reset with gtk_cell_area_context_reset(),
the returned value will be -1.
Parameters
Since 3.0
gtk_cell_area_context_push_preferred_width ()
void gtk_cell_area_context_push_preferred_width (GtkCellAreaContext *context,gint minimum_width,gint natural_width);
Causes the minimum and/or natural width to grow if the new proposed sizes exceed the current minimum and natural width.
This is used by GtkCellAreaContext implementations during
the request process over a series of GtkTreeModel rows to
progressively push the requested width over a series of
gtk_cell_area_get_preferred_width() requests.
Parameters
context |
||
minimum_width |
the proposed new minimum width for |
|
natural_width |
the proposed new natural width for |
Since 3.0
gtk_cell_area_context_push_preferred_height ()
void gtk_cell_area_context_push_preferred_height (GtkCellAreaContext *context,gint minimum_height,gint natural_height);
Causes the minimum and/or natural height to grow if the new proposed sizes exceed the current minimum and natural height.
This is used by GtkCellAreaContext implementations during
the request process over a series of GtkTreeModel rows to
progressively push the requested height over a series of
gtk_cell_area_get_preferred_height() requests.
Parameters
context |
||
minimum_height |
the proposed new minimum height for |
|
natural_height |
the proposed new natural height for |
Since 3.0
Types and Values
struct GtkCellAreaContextClass
struct GtkCellAreaContextClass {
void (* allocate) (GtkCellAreaContext *context,
gint width,
gint height);
void (* reset) (GtkCellAreaContext *context);
void (* get_preferred_height_for_width) (GtkCellAreaContext *context,
gint width,
gint *minimum_height,
gint *natural_height);
void (* get_preferred_width_for_height) (GtkCellAreaContext *context,
gint height,
gint *minimum_width,
gint *natural_width);
};
Members
This tells the context that an allocation width or height
(or both) have been decided for a group of rows. The context should
store any allocations for internally aligned cells at this point so
that they dont need to be recalculated at |
||
Clear any previously stored information about requested and allocated sizes for the context. |
||
Returns the aligned height for the given width that context must store while collecting sizes for it’s rows. |
||
Returns the aligned width for the given height that context must store while collecting sizes for it’s rows. |
Property Details
The “area” property
“area” GtkCellArea *
The GtkCellArea this context was created by
Flags: Read / Write / Construct Only
Since 3.0
The “minimum-height” property
“minimum-height” gint
The minimum height for the GtkCellArea in this context
for all GtkTreeModel rows that this context was requested
for using gtk_cell_area_get_preferred_height().
Flags: Read
Allowed values: >= -1
Default value: -1
Since 3.0
The “minimum-width” property
“minimum-width” gint
The minimum width for the GtkCellArea in this context
for all GtkTreeModel rows that this context was requested
for using gtk_cell_area_get_preferred_width().
Flags: Read
Allowed values: >= -1
Default value: -1
Since 3.0
The “natural-height” property
“natural-height” gint
The natural height for the GtkCellArea in this context
for all GtkTreeModel rows that this context was requested
for using gtk_cell_area_get_preferred_height().
Flags: Read
Allowed values: >= -1
Default value: -1
Since 3.0
The “natural-width” property
“natural-width” gint
The natural width for the GtkCellArea in this context
for all GtkTreeModel rows that this context was requested
for using gtk_cell_area_get_preferred_width().
Flags: Read
Allowed values: >= -1
Default value: -1
Since 3.0