Tk_MaintainGeometry(3Tk)Tk_MaintainGeometry(3Tk)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.
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:
(a) 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.
(b) If the master window, or any of its ancestors up to the 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.
(c) 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.
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Tk_MaintainGeometry(3Tk)Tk_MaintainGeometry(3Tk)
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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