Tk_MaintainGeometry(3) Tk Library Procedures Tk_MaintainGeometry(3)

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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
controlled.

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 border.

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 border.

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
geometry managers to deal with windows whose containers are not their
parents. 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
window's parent, is moved, then the window must be
repositioned within its parent in order to maintain the
correct position relative 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
containers are not their parents, as well as handling the simpler
case of windows whose container are their parents.
Tk_MaintainGeometry is typically 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-window pair, the information from the most recent call
supersedes any older information. If Tk_UnmaintainGeometry is called
for a container-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)