path: root/doc/place.n

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'\" Copyright (c) 1992 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
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.TH place n "" Tk "Tk Built-In Commands"
.so man.macros
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
place \- Geometry manager for fixed or rubber-sheet placement
.SH SYNOPSIS
\fBplace \fIoption arg \fR?\fIarg ...\fR?
.BE
.SH DESCRIPTION
.PP
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 \fIcontent\fR,
within another window, called the \fIcontainer\fR.
The placer also provides rubber-sheet placement, where you specify the
size and location of the content in terms of the dimensions of
the container, so that the content changes size and location
in response to changes in the size of the container.
Lastly, the placer allows you to mix these styles of placement so
that, for example, the content has a fixed width and height but is
centered inside the container.
.PP
.TP
\fBplace \fIwindow option value \fR?\fIoption value ...\fR?
Arrange for the placer to manage the geometry of a content whose
pathName is \fIwindow\fR.  The remaining arguments consist of one or
more \fIoption\-value\fR pairs that specify the way in which
\fIwindow\fR's geometry is managed.  \fIOption\fR may have any of the
values accepted by the \fBplace configure\fR command.
.TP
\fBplace configure \fIwindow \fR?\fIoption\fR? ?\fIvalue option value ...\fR?
Query or modify the geometry options of the content given by
\fIwindow\fR.  If no \fIoption\fR is specified, this command returns a
list describing the available options (see \fBTk_ConfigureInfo\fR for
information on the format of this list).  If \fIoption\fR is specified
with no \fIvalue\fR, then the command returns a list describing the
one named option (this list will be identical to the corresponding
sublist of the value returned if no \fIoption\fR is specified).  If
one or more \fIoption\-value\fR pairs are specified, then the command
modifies the given option(s) to have the given value(s); in this case
the command returns an empty string.
.RS
.PP
The following \fIoption\-value\fR pairs are supported:
.TP
\fB\-anchor \fIwhere\fR
\fIWhere\fR specifies which point of \fIwindow\fR is to be positioned
at the (x,y) location selected by the \fB\-x\fR, \fB\-y\fR,
\fB\-relx\fR, and \fB\-rely\fR options.
The anchor point is in terms of the outer area of \fIwindow\fR
including its border, if any.
Thus if \fIwhere\fR is \fBse\fR then the lower-right corner of
\fIwindow\fR's border will appear at the given (x,y) location
in the container.
The anchor position defaults to \fBnw\fR.
.TP
\fB\-bordermode \fImode\fR
\fIMode\fR determines the degree to which borders within the
container are used in determining the placement of the content.
The default and most common value is \fBinside\fR.
In this case the placer considers the area of the container to
be the innermost area of the container, inside any border:
an option of \fB\-x 0\fR corresponds to an x-coordinate just
inside the border and an option of \fB\-relwidth 1.0\fR
means \fIwindow\fR will fill the area inside the container's
border.
.RS
.PP
If \fImode\fR is \fBoutside\fR then the placer considers
the area of the container to include its border;
this mode is typically used when placing \fIwindow\fR
outside its container, as with the options \fB\-x 0 \-y 0 \-anchor ne\fR.
Lastly, \fImode\fR may be specified as \fBignore\fR, in which
case borders are ignored:  the area of the container is considered
to be its official X area, which includes any internal border but
no external border.  A bordermode of \fBignore\fR is probably
not very useful.
.RE
.TP
\fB\-height \fIsize\fR
\fISize\fR specifies the height for \fIwindow\fR in screen units
(i.e. any of the forms accepted by \fBTk_GetPixels\fR).
The height will be the outer dimension of \fIwindow\fR including its
border, if any.
If \fIsize\fR is an empty string, or if no \fB\-height\fR or
\fB\-relheight\fR option is specified, then the height requested
internally by the window will be used.
.TP
\fB\-in \fIcontainer\fR
\fIContainer\fR specifies the path name of the window relative
to which \fIwindow\fR is to be placed.
\fIContainer\fR must either be \fIwindow\fR's parent or a descendant
of \fIwindow\fR's parent.
In addition, \fIcontainer\fR and \fIwindow\fR must both be descendants
of the same top-level window.
These restrictions are necessary to guarantee
that \fIwindow\fR is visible whenever \fIcontainer\fR is visible.
If this option is not specified then the other window defaults to
\fIwindow\fR's parent.
.TP
\fB\-relheight \fIsize\fR
\fISize\fR specifies the height for \fIwindow\fR.
In this case the height is specified as a floating-point number
relative to the height of the container: 0.5 means \fIwindow\fR will
be half as high as the container, 1.0 means \fIwindow\fR will have
the same height as the container, and so on.
If both \fB\-height\fR and \fB\-relheight\fR are specified for a content,
their values are summed.  For example, \fB\-relheight 1.0 \-height \-2\fR
makes the content 2 pixels shorter than the container.
.TP
\fB\-relwidth \fIsize\fR
\fISize\fR specifies the width for \fIwindow\fR.
In this case the width is specified as a floating-point number
relative to the width of the container: 0.5 means \fIwindow\fR will
be half as wide as the container, 1.0 means \fIwindow\fR will have
the same width as the container, and so on.
If both \fB\-width\fR and \fB\-relwidth\fR are specified for a content,
their values are summed.  For example, \fB\-relwidth 1.0 \-width 5\fR
makes the content 5 pixels wider than the container.
.TP
\fB\-relx \fIlocation\fR
\fILocation\fR specifies the x-coordinate within the container window
of the anchor point for \fIwindow\fR.
In this case the location is specified in a relative fashion
as a floating-point number:  0.0 corresponds to the left edge
of the container and 1.0 corresponds to the right edge of the container.
\fILocation\fR need not be in the range 0.0\-1.0.
If both \fB\-x\fR and \fB\-relx\fR are specified for a content
then their values are summed.  For example, \fB\-relx 0.5 \-x \-2\fR
positions the left edge of the content 2 pixels to the left of the
center of its container.
.TP
\fB\-rely \fIlocation\fR
\fILocation\fR specifies the y-coordinate within the container window
of the anchor point for \fIwindow\fR.
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 container and 1.0 corresponds to the bottom edge of the container.
\fILocation\fR need not be in the range 0.0\-1.0.
If both \fB\-y\fR and \fB\-rely\fR are specified for a content
then their values are summed.  For example, \fB\-rely 0.5 \-x 3\fR
positions the top edge of the content 3 pixels below the
center of its container.
.TP
\fB\-width \fIsize\fR
\fISize\fR specifies the width for \fIwindow\fR in screen units
(i.e. any of the forms accepted by \fBTk_GetPixels\fR).
The width will be the outer width of \fIwindow\fR including its
border, if any.
If \fIsize\fR is an empty string, or if no \fB\-width\fR
or \fB\-relwidth\fR option is specified, then the width requested
internally by the window will be used.
.TP
\fB\-x \fIlocation\fR
\fILocation\fR specifies the x-coordinate within the container window
of the anchor point for \fIwindow\fR.
The location is specified in screen units (i.e. any of the forms
accepted by \fBTk_GetPixels\fR) and need not lie within the bounds
of the container window.
.TP
\fB\-y \fIlocation\fR
\fILocation\fR specifies the y-coordinate within the container window
of the anchor point for \fIwindow\fR.
The location is specified in screen units (i.e. any of the forms
accepted by \fBTk_GetPixels\fR) and need not lie within the bounds
of the container window.
.PP
If the same value is specified separately with
two different options, such as \fB\-x\fR and \fB\-relx\fR, then
the most recent option is used and the older one is ignored.
.RE
.TP
\fBplace forget \fIwindow\fR
Causes the placer to stop managing the geometry of \fIwindow\fR.  As a
side effect of this command \fIwindow\fR will be unmapped so that it
does not appear on the screen.  If \fIwindow\fR is not currently managed
by the placer then the command has no effect.  This command returns an
empty string.
.TP
\fBplace info \fIwindow\fR
Returns a list giving the current configuration of \fIwindow\fR.
The list consists of \fIoption\-value\fR pairs in exactly the
same form as might be specified to the \fBplace configure\fR
command.
.TP
\fBplace slaves \fIwindow\fR
Returns a list of all the content windows for which \fIwindow\fR is the container.
If there is no content for \fIwindow\fR then an empty string is returned.
.VS "TIP 581"
.TP
\fBplace content \fIwindow\fR
.
Synonym for \fBplace slaves \fIwindow\fR.
.VE "TIP 581"
.PP
If the configuration of a window has been retrieved with
\fBplace info\fR, that configuration can be restored later by
first using \fBplace forget\fR to erase any existing information
for the window and then invoking \fBplace configure\fR with
the saved information.
.SH "FINE POINTS"
.PP
It is not necessary for the container window to be the parent
of the content window.
This feature is useful in at least two situations.
First, for complex window layouts it means you can create a
hierarchy of subwindows whose only purpose
is to assist in the layout of the parent.
The
.QW "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
.QW "real children"
do not reflect the geometry-management hierarchy and users
can specify options for the real children
without being aware of the structure of the geometry-management
hierarchy.
.PP
A second reason for having a container different than the content'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
.CS
\fB\-in \fIsibling\fB \-relx 0.5 \-rely 1.0 \-anchor n \-bordermode outside\fR
.CE
Whenever the sibling is repositioned in the future, the content
will be repositioned as well.
.PP
Unlike many other geometry managers (such as the packer)
the placer does not make any attempt to manipulate the geometry of
the container windows or the parents of content windows (i.e. it does not
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.
.SH EXAMPLE
.PP
Make the label occupy the middle bit of the toplevel, no matter how it
is resized:
.CS
label .l \-text "In the\enMiddle!" \-bg black \-fg white
\fBplace\fR .l \-relwidth .3 \-relx .35 \-relheight .3 \-rely .35
.CE
.SH "SEE ALSO"
grid(n), pack(n)
.SH KEYWORDS
geometry manager, height, location, container, place, rubber sheet, content, width
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