Tk_MaintainGeometry(3)Tk Library ProceduresTk_MaintainGeometry(3)_________________________________________________________________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.
_________________________________________________________________DESCRIPTIONTk_MaintainGeometry and Tk_UnmaintainGeometry make it eas-
ier for geometry managers to deal with slaves whose mas-
ters 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 trans-
lated 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
Tk 4.0 1
Tk_MaintainGeometry(3)Tk Library ProceduresTk_MaintainGeometry(3)
the slave's parent, is moved, then the slave must
be repositioned within its parent in order to main-
tain 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 mas-
ter 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 remem-
bers 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_MaintainGeome-
try for the master-slave pair, so that the slave's geome-
try and mapped state are no longer maintained automati-
cally. 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 automat-
ically.
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_Unmaintain-
Geometry 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
Tk 4.0 2
