place(3) User Contributed Perl Documentation place(3)NAMETk::place - Geometry manager for fixed or rubber-sheet placement
SYNOPSIS
$widget->place?(-option=>value?, -option=>value, ...)?
$widget->placeForget
$widget->placeInfo
$master->placeSlaves
DESCRIPTION
The placer is a geometry manager for Tk. It provides simple fixed
placement of windows, where you specify the exact size and location of
one window, called the slave, within another window, called the $mas‐
ter. The placer also provides rubber-sheet placement, where you spec‐
ify the size and location of the slave in terms of the dimensions of
the master, so that the slave changes size and location in response to
changes in the size of the master. Lastly, the placer allows you to
mix these styles of placement so that, for example, the slave has a
fixed width and height but is centered inside the master.
$slave->place?(-option=>value?, -option=>value, ...?)?
The place method arranges for the placer to manage the geometry of
$slave. The remaining arguments consist of one or more
-option=>value pairs that specify the way in which $slave's geome‐
try is managed. If the placer is already managing $slave, then the
-option=>value pairs modify the configuration for $slave. The
place method returns an empty string as result. The following
-option=>value pairs are supported:
-in => $master
$master is the reference to the window relative to which
$slave is to be placed. $master must either be $slave's
parent or a descendant of $slave's parent. In addition,
$master and $slave must both be descendants of the same
top-level window. These restrictions are necessary to
guarantee that $slave is visible whenever $master is visi‐
ble. If this option isn't specified then the master
defaults to $slave's parent.
-x => location
Location specifies the x-coordinate within the master win‐
dow of the anchor point for $slave widget. The location is
specified in screen units (i.e. any of the forms accepted
by Tk_GetPixels) and need not lie within the bounds of the
master window.
-relx => location
Location specifies the x-coordinate within the master win‐
dow of the anchor point for $slave widget. In this case
the location is specified in a relative fashion as a float‐
ing-point number: 0.0 corresponds to the left edge of the
master and 1.0 corresponds to the right edge of the master.
Location need not be in the range 0.0-1.0. If both -x and
-relx are specified for a slave then their values are
summed. For example, "-relx=>0.5, -x=-2" positions the
left edge of the slave 2 pixels to the left of the center
of its master.
-y => location
Location specifies the y-coordinate within the master win‐
dow of the anchor point for $slave widget. The location is
specified in screen units (i.e. any of the forms accepted
by Tk_GetPixels) and need not lie within the bounds of the
master window.
-rely => location
Location specifies the y-coordinate within the master win‐
dow of the anchor point for $slave widget. In this case
the value is specified in a relative fashion as a floating-
point number: 0.0 corresponds to the top edge of the mas‐
ter and 1.0 corresponds to the bottom edge of the master.
Location need not be in the range 0.0-1.0. If both -y and
-rely are specified for a slave then their values are
summed. For example, -rely=>0.5, -x=>3 positions the top
edge of the slave 3 pixels below the center of its master.
-anchor => where
Where specifies which point of $slave is to be positioned
at the (x,y) location selected by the -x, -y, -relx, and
-rely options. The anchor point is in terms of the outer
area of $slave including its border, if any. Thus if where
is se then the lower-right corner of $slave's border will
appear at the given (x,y) location in the master. The
anchor position defaults to nw.
-width => size
Size specifies the width for $slave in screen units (i.e.
any of the forms accepted by Tk_GetPixels). The width will
be the outer width of $slave including its border, if any.
If size is an empty string, or if no -width or -relwidth
option is specified, then the width requested internally by
the window will be used.
-relwidth => size
Size specifies the width for $slave. In this case the
width is specified as a floating-point number relative to
the width of the master: 0.5 means $slave will be half as
wide as the master, 1.0 means $slave will have the same
width as the master, and so on. If both -width and -rel‐
width are specified for a slave, their values are summed.
For example, -relwidth=>1.0, -width=>5 makes the slave 5
pixels wider than the master.
-height => size
Size specifies the height for $slave in screen units (i.e.
any of the forms accepted by Tk_GetPixels). The height
will be the outer dimension of $slave including its border,
if any. If size is an empty string, or if no -height or
-relheight option is specified, then the height requested
internally by the window will be used.
-relheight => size
Size specifies the height for $slave. In this case the
height is specified as a floating-point number relative to
the height of the master: 0.5 means $slave will be half as
high as the master, 1.0 means $slave will have the same
height as the master, and so on. If both -height and -rel‐
height are specified for a slave, their values are summed.
For example, -relheight=>1.0, -height=>-2 makes the slave 2
pixels shorter than the master.
-bordermode => mode
Mode determines the degree to which borders within the mas‐
ter are used in determining the placement of the slave.
The default and most common value is inside. In this case
the placer considers the area of the master to be the
innermost area of the master, inside any border: an option
of -x=>0 corresponds to an x-coordinate just inside the
border and an option of -relwidth=>1.0 means $slave will
fill the area inside the master's border. If mode is out‐
side then the placer considers the area of the master to
include its border; this mode is typically used when plac‐
ing $slave outside its master, as with the options -x=>0,
-y=>0, -anchor=>ne. Lastly, mode may be specified as
ignore, in which case borders are ignored: the area of the
master is considered to be its official X area, which
includes any internal border but no external border. A
bordermode of ignore is probably not very useful.
If the same value is specified separately with two differ‐
ent options, such as -x and -relx, then the most recent
option is used and the older one is ignored.
$slave->placeSlaves
The placeSlaves method returns a list of all the slave windows for
which $master is the master. If there are no slaves for $master
then an empty list is returned.
$slave->placeForget
The placeForget method causes the placer to stop managing the geom‐
etry of $slave. As a side effect of this method call $slave will
be unmapped so that it doesn't appear on the screen. If $slave
isn't currently managed by the placer then the method call has no
effect. placeForget returns an empty string as result.
$slave->placeInfo
The placeInfo method returns a list giving the current configura‐
tion of $slave. The list consists of -option=>value pairs in
exactly the same form as might be specified to the place method.
If the configuration of a window has been retrieved with placeInfo,
that configuration can be restored later by first using placeForget
to erase any existing information for the window and then invoking
place with the saved information.
FINE POINTS
It is not necessary for the master window to be the parent of the slave
window. This feature is useful in at least two situations. First, for
complex window layouts it means you can create a hierarchy of subwin‐
dows whose only purpose is to assist in the layout of the parent. The
``real children'' of the parent (i.e. the windows that are significant
for the application's user interface) can be children of the parent yet
be placed inside the windows of the geometry-management hierarchy.
This means that the path names of the ``real children'' don't reflect
the geometry-management hierarchy and users can specify options for the
real children without being aware of the structure of the geometry-man‐
agement hierarchy.
A second reason for having a master different than the slave's parent
is to tie two siblings together. For example, the placer can be used
to force a window always to be positioned centered just below one of
its siblings by specifying the configuration
-in=>$sibling, -relx=>0.5, -rely=>1.0, -anchor=>'n', -border‐
mode=>'outside'
Whenever the $sibling widget is repositioned in the future, the slave
will be repositioned as well.
Unlike many other geometry managers (such as the packer) the placer
does not make any attempt to manipulate the geometry of the master win‐
dows or the parents of slave windows (i.e. it doesn't set their
requested sizes). To control the sizes of these windows, make them
windows like frames and canvases that provide configuration options for
this purpose.
SEE ALSO
Tk::form Tk::grid Tk::pack
KEYWORDS
geometry manager, height, location, master, place, rubber sheet, slave,
width
perl v5.8.8 2004-02-28 place(3)
