Tk_MaintainGeometry(3) Tk Library Procedures Tk_MaintainGeometry(3) ______________________________________________________________________________
NAME
Tk_MaintainGeometry, Tk_UnmaintainGeometry - maintain geometry of one
window relative to another
SYNOPSIS
#include <tk.h>
Tk_MaintainGeometry(window, container, x, y, width, height)
Tk_UnmaintainGeometry(window, container)
ARGUMENTS
Tk_Window window (in) Window whose geometry is to be con-
trolled.
Tk_Window container (in) Window relative to which window's
geometry will be controlled.
int x (in) Desired x-coordinate of window in
container, measured in pixels from
the inside of container's left border
to the outside of window's left bor-
der.
int y (in) Desired y-coordinate of window in
container, measured in pixels from
the inside of container's top border
to the outside of window's top bor-
der.
int width (in) Desired width for window, in pixels.
int height (in) Desired height for window, in pixels.
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DESCRIPTION
Tk_MaintainGeometry and Tk_UnmaintainGeometry make it easier for geome-
try managers to deal with windows whose containers are not their par-
ents. Three problems arise if the container for a window is not its
parent:
[1] The x- and y-position of the window must be translated from the
coordinate system of the container to that of the parent before
positioning the window.
[2] If the container window, or any of its ancestors up to the win-
dow's parent, is moved, then the window must be repositioned
within its parent in order to maintain the correct position rel-
ative to the container.
[3] If the container or one of its ancestors is mapped or unmapped,
then the window must be mapped or unmapped to correspond.
None of these problems is an issue if the parent and container are the
same. For example, if the container or one of its ancestors is
unmapped, the window is automatically removed by the screen by X.
Tk_MaintainGeometry deals with these problems for windows whose con-
tainers are not their parents, as well as handling the simpler case of
windows whose container are their parents. Tk_MaintainGeometry is typ-
ically called by a window manager once it has decided where a window
should be positioned relative to its container. Tk_MaintainGeometry
translates the coordinates to the coordinate system of window's parent
and then moves and resizes the window appropriately. Furthermore, it
remembers the desired position and creates event handlers to monitor
the container and all of its ancestors up to (but not including) the
window's parent. If any of these windows is moved, mapped, or
unmapped, the window will be adjusted so that it is mapped only when
the container is mapped and its geometry relative to the container
remains as specified by x, y, width, and height.
When a window manager relinquishes control over a window, or if it
decides that it does not want the window to appear on the screen under
any conditions, it calls Tk_UnmaintainGeometry. Tk_UnmaintainGeometry
unmaps the window and cancels any previous calls to Tk_MaintainGeometry
for the container-window pair, so that the window's geometry and mapped
state are no longer maintained automatically. Tk_UnmaintainGeometry
need not be called by a geometry manager if the window, the container,
or any of the container's ancestors is destroyed: Tk will call it
automatically.
If Tk_MaintainGeometry is called repeatedly for the same container-win-
dow pair, the information from the most recent call supersedes any
older information. If Tk_UnmaintainGeometry is called for a con-
tainer-window pair that is is not currently managed, the call has no
effect.
KEYWORDS
geometry manager, map, container, parent, position, window, unmap
Tk 4.0 Tk_MaintainGeometry(3)
tk 8.6.11 - Generated Fri Jan 22 15:38:19 CST 2021