240 lines
8.2 KiB
Groff
240 lines
8.2 KiB
Groff
'\"
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'\" Copyright (c) 1990 The Regents of the University of California.
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'\" All rights reserved.
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'\"
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'\" Permission is hereby granted, without written agreement and without
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'\" license or royalty fees, to use, copy, modify, and distribute this
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'\" documentation for any purpose, provided that the above copyright
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'\" notice and the following two paragraphs appear in all copies.
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'\"
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'\" IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
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'\" FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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'\" ARISING OUT OF THE USE OF THIS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
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'\" CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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'\"
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'\" THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
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'\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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'\" AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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'\" ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
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'\" PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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'\"
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'\" $Header: /user6/ouster/wish/man/RCS/GetBitmap.3,v 1.11 93/04/01 09:41:24 ouster Exp $ SPRITE (Berkeley)
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'\"
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.so man.macros
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.HS Tk_GetBitmap tkc
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.BS
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.SH NAME
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Tk_GetBitmap, Tk_DefineBitmap, Tk_NameOfBitmap, Tk_SizeOfBitmap, Tk_FreeBitmap, Tk_GetBitmapFromData \- maintain database of single-plane pixmaps
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.SH SYNOPSIS
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.nf
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\fB#include <tk.h>\fR
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.sp
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Pixmap
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\fBTk_GetBitmap(\fIinterp, tkwin, id\fB)\fR
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.sp
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.VS
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int
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\fBTk_DefineBitmap(\fIinterp, nameId, source, width, height\fR)\fR
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.VE
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.sp
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Tk_Uid
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.VS
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\fBTk_NameOfBitmap(\fIdisplay, bitmap\fB)\fR
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.sp
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\fBTk_SizeOfBitmap(\fIdisplay, bitmap, widthPtr, heightPtr\fB)\fR
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.sp
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\fBTk_FreeBitmap(\fIdisplay, bitmap\fB)\fR
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.VE
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.SH ARGUMENTS
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.AS "unsigned long" *pixelPtr
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.AP Tcl_Interp *interp in
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Interpreter to use for error reporting.
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.AP Tk_Window tkwin in
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Token for window in which the bitmap will be used.
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.AP Tk_Uid id in
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Description of bitmap; see below for possible values.
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.AP Tk_Uid *nameId in
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Name for new bitmap to be defined.
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.AP char *source in
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Data for bitmap, in standard bitmap format.
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Must be stored in static memory whose value will never change.
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.AP "unsigned int" width in
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Width of bitmap.
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.AP "unsigned int" height in
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Height of bitmap.
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.AP "unsigned int" *widthPtr out
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Pointer to word to fill in with \fIbitmap\fR's width.
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.AP "unsigned int" *heightPtr out
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Pointer to word to fill in with \fIbitmap\fR's height.
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.AP Display *display in
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Display for which \fIbitmap\fR was allocated.
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.VS
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.VE
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.AP Pixmap bitmap in
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Identifier for a bitmap allocated by \fBTk_GetBitmap\fR.
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.BE
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.SH DESCRIPTION
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.PP
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These procedures manage a collection of bitmaps (one-plane pixmaps)
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being used by an application. The procedures allow bitmaps to be
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re-used efficiently, thereby avoiding server overhead, and also
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allow bitmaps to be named with character strings.
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.PP
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\fBTk_GetBitmap\fR takes as argument a Tk_Uid describing a bitmap.
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It returns a Pixmap identifier for a bitmap corresponding to the
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description. It re-uses an existing bitmap, if possible, and
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creates a new one otherwise. At present, \fIid\fR must have
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one of the following forms:
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.TP 20
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\fB@\fIfileName\fR
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\fIFileName\fR must be the name of a file containing a bitmap
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description in the standard X11 or X10 format.
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.TP 20
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\fIname\fR
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\fIName\fR must be the name of a bitmap defined previously with
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a call to \fBTk_DefineBitmap\fR. The following names are pre-defined
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by Tk:
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.RS
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.TP 12
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\fBerror\fR
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.VS
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The international "don't" symbol: a circle with a diagonal line
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across it.
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.VE
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.TP 12
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\fBgray50\fR
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50% gray: a checkerboard pattern where every other bit is on.
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.TP 12
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\fBgray25\fR
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25% gray: a pattern where 25% of the bits are on, consisting of all the
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bit positions that can be reached by a chess knight starting at (0,0).
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.TP 12
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\fBhourglass\fR
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.VS
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An hourglass symbol.
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.TP 12
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\fBinfo\fR
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A large letter ``i''.
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.TP 12
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\fBquesthead\fR
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The silhouette of a human head, with a question mark in it.
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.TP 12
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\fBquestion\fR
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A large question-mark.
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.TP 12
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\fBwarning\fR
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A large exclamation point.
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.VE
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\fB
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.RE
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.LP
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Under normal conditions, \fBTk_GetBitmap\fR
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returns an identifier for the requested bitmap. If an error
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occurs in creating the bitmap, such as when \fIid\fR refers
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to a non-existent file, then \fBNone\fR is returned and an error
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message is left in \fIinterp->result\fR.
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.PP
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\fBTk_DefineBitmap\fR associates a name with
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.VS
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in-memory bitmap data so that the name can be used in later
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calls to \fBTk_GetBitmap\fR. The \fInameId\fR
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argument gives a name for the bitmap; it must not previously
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have been used in a call to \fBTk_DefineBitmap\fR.
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The arguments \fIsource\fR, \fIwidth\fR, and \fIheight\fR
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describe the bitmap.
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\fBTk_DefineBitmap\fR normally returns TCL_OK; if an error occurs
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(e.g. a bitmap named \fInameId\fR has already been defined) then
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TCL_ERROR is returned and an error message is left in
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\fIinterp->result\fR.
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Note: \fBTk_DefineBitmap\fR expects the memory pointed to by
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\fIsource\fR to be static: \fBTk_DefineBitmap\fR doesn't make
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a private copy of this memory, but uses the bytes pointed to
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by \fIsource\fR later in calls to \fBTk_GetBitmap\fR.
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.VE
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.PP
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Typically \fBTk_DefineBitmap\fR is used by \fB#include\fR-ing a
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bitmap file directly into a C program and then referencing
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the variables defined by the file.
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For example, suppose there exists a file \fBstip.bitmap\fR,
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which was created by the \fBbitmap\fR program and contains
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a stipple pattern.
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The following code uses \fBTk_DefineBitmap\fR to define a
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new bitmap named \fBfoo\fR:
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.nf
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.RS
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\fCPixmap bitmap;
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#include "stip.bitmap"
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Tk_DefineBitmap(interp, Tk_GetUid("foo"), stip_bits,
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stip_width, stip_height);
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\&...
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bitmap = Tk_GetBitmap(interp, tkwin, Tk_GetUid("foo"));\fR
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.RE
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.fi
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This code causes the bitmap file to be read
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at compile-time and incorporates the bitmap information into
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the program's executable image. The same bitmap file could be
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read at run-time using \fBTk_GetBitmap\fR:
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.nf
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.RS
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\fCPixmap bitmap;
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bitmap = Tk_GetBitmap(interp, tkwin, Tk_GetUid("@stip.bitmap"));\fR
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.RE
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.fi
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The second form is a bit more flexible (the file could be modified
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after the program has been compiled, or a different string could be
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provided to read a different file), but it is a little slower and
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requires the bitmap file to exist separately from the program.
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.PP
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\fBTk_GetBitmap\fR maintains a
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database of all the bitmaps that have been created.
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Whenever possible, it will return an existing bitmap rather
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than creating a new one.
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This approach can substantially reduce server overhead, so
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\fBTk_GetBitmap\fR should generally be used in preference to Xlib
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procedures like \fBXReadBitmapFile\fR.
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.PP
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The bitmaps returned by \fBTk_GetBitmap\fR
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are shared, so callers should never modify them.
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If a bitmap must be modified dynamically, then it should be
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created by calling Xlib procedures such as \fBXReadBitmapFile\fR
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or \fBXCreatePixmap\fR directly.
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.PP
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The procedure \fBTk_NameOfBitmap\fR is roughly the inverse of
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\fBTk_GetBitmap\fR.
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Given an X Pixmap argument, it returns the \fIid\fR that was
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passed to \fBTk_GetBitmap\fR when the bitmap was created.
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.VS
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\fIBitmap\fR must have been the return value from a previous
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call to \fBTk_GetBitmap\fR.
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.VE
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.PP
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\fBTk_SizeOfBitmap\fR returns the dimensions of its \fIbitmap\fR
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.VS
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argument in the words pointed to by the \fIwidthPtr\fR and
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\fIheightPtr\fR arguments. As with \fBTk_NameOfBitmap\fR,
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\fIbitmap\fR must have been created by \fBTk_GetBitmap\fR.
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.VE
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.PP
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When a bitmap returned by \fBTk_GetBitmap\fR
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is no longer needed, \fBTk_FreeBitmap\fR should be called to release it.
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There should be exactly one call to \fBTk_FreeBitmap\fR for
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each call to \fBTk_GetBitmap\fR.
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When a bitmap is no longer in use anywhere (i.e. it has been freed as
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many times as it has been gotten) \fBTk_FreeBitmap\fR will release
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it to the X server and delete it from the database.
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.SH BUGS
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In determining whether an existing bitmap can be used to satisfy
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a new request, \fBTk_GetBitmap\fR
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considers only the immediate value of its \fIid\fR argument. For
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example, when a file name is passed to \fBTk_GetBitmap\fR,
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\fBTk_GetBitmap\fR will assume it is safe to re-use an existing
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bitmap created from the same file name: it will not check to
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see whether the file itself has changed, or whether the current
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directory has changed, thereby causing the name to refer to
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a different file.
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.SH KEYWORDS
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bitmap, pixmap
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