Tk_MaintainGeometry(3) Tk (4.0) 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(slave, master, x, y, width, height)
Tk_UnmaintainGeometry(slave, master)
ARGUMENTS
Tk_Window slave (in) Window whose geometry is to
be controlled.
Tk_Window master (in) Window relative to which
slave's geometry will be
controlled.
int x (in) Desired x-coordinate of slave
in master, measured in pixels
from the inside of master's
left border to the outside of
slave's left border.
int y (in) Desired y-coordinate of slave
in master, measured in pixels
from the inside of master's
top border to the outside of
slave's top border.
int width (in) Desired width for slave, in
pixels.
int height (in) Desired height for slave, in
pixels.
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DESCRIPTION
Tk_MaintainGeometry and Tk_UnmaintainGeometry make it easier
for geometry managers to deal with slaves whose masters are
not their parents. Three problems arise if the master for a
slave is not its parent:
[1] The x- and y-position of the slave must be translated
from the coordinate system of the master to that of the
parent before positioning the slave.
[2] If the master window, or any of its ancestors up to the
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Tk_MaintainGeometry(3) Tk (4.0) Tk_MaintainGeometry(3)
slave's parent, is moved, then the slave must be
repositioned within its parent in order to maintain the
correct position relative to the master.
[3] If the master or one of its ancestors is mapped or
unmapped, then the slave must be mapped or unmapped to
correspond.
None of these problems is an issue if the parent and master
are the same. For example, if the master or one of its
ancestors is unmapped, the slave is automatically removed by
the screen by X.
Tk_MaintainGeometry deals with these problems for slaves
whose masters aren't their parents. Tk_MaintainGeometry is
typically called by a window manager once it has decided
where a slave should be positioned relative to its master.
Tk_MaintainGeometry translates the coordinates to the
coordinate system of slave's parent and then moves and
resizes the slave appropriately. Furthermore, it remembers
the desired position and creates event handlers to monitor
the master and all of its ancestors up to (but not
including) the slave's parent. If any of these windows is
moved, mapped, or unmapped, the slave will be adjusted so
that it is mapped only when the master is mapped and its
geometry relative to the master 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 master-slave pair, so that the slave's geometry and
mapped state are no longer maintained automatically.
Tk_UnmaintainGeometry need not be called by a geometry
manager if the slave, the master, or any of the master's
ancestors is destroyed: Tk will call it automatically.
If Tk_MaintainGeometry is called repeatedly for the same
master-slave pair, the information from the most recent call
supersedes any older information. If Tk_UnmaintainGeometry
is called for a master-slave pair that is isn't currently
managed, the call has no effect.
KEYWORDS
geometry manager, map, master, parent, position, slave,
unmap
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