297 lines
10 KiB
Groff
297 lines
10 KiB
Groff
'\"
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'\" Copyright (c) 1990 The Regents of the University of California.
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'\" Copyright (c) 1994-1998 Sun Microsystems, Inc.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH Tk_AllocBitmapFromObj 3 8.1 Tk "Tk Library Procedures"
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.so man.macros
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.BS
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.SH NAME
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Tk_AllocBitmapFromObj, Tk_GetBitmap, Tk_GetBitmapFromObj, Tk_DefineBitmap, Tk_NameOfBitmap, Tk_SizeOfBitmap, Tk_FreeBitmapFromObj, Tk_FreeBitmap \- 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_AllocBitmapFromObj(\fIinterp, tkwin, objPtr\fB)\fR
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.sp
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Pixmap
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\fBTk_GetBitmap(\fIinterp, tkwin, info\fB)\fR
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.sp
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Pixmap
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\fBTk_GetBitmapFromObj(\fItkwin, objPtr\fB)\fR
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.sp
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int
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\fBTk_DefineBitmap(\fIinterp, name, source, width, height\fB)\fR
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.sp
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const char *
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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_FreeBitmapFromObj(\fItkwin, objPtr\fB)\fR
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.sp
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\fBTk_FreeBitmap(\fIdisplay, bitmap\fB)\fR
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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; if NULL then no error message
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is left after errors.
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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 Tcl_Obj *objPtr in/out
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String value describes desired bitmap; internal rep will be
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modified to cache pointer to corresponding Pixmap.
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.AP "const char" *info in
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Same as \fIobjPtr\fR except description of bitmap is passed as a string and
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resulting Pixmap is not cached.
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.AP "const char" *name in
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Name for new bitmap to be defined.
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.AP "const void" *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 "int" width in
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Width of bitmap.
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.AP "int" height in
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Height of bitmap.
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.AP "int" *widthPtr out
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Pointer to word to fill in with \fIbitmap\fR's width.
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.AP "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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.AP Pixmap bitmap in
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Identifier for a bitmap allocated by \fBTk_AllocBitmapFromObj\fR or
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\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_AllocBitmapFromObj\fR returns a Pixmap identifier for a bitmap
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that matches the description in \fIobjPtr\fR and is suitable for use
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in \fItkwin\fR. It re-uses an existing bitmap, if possible, and
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creates a new one otherwise. \fIObjPtr\fR's value must have one
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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 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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The international
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.QW don't
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symbol: a circle with a diagonal line across it.
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.TP 12
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\fBgray75\fR
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75% gray: a checkerboard pattern where three out of four bits are on.
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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 checkerboard pattern where one out of every four bits is on.
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.TP 12
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\fBgray12\fR
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12.5% gray: a pattern where one-eighth of the bits are on, consisting of
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every fourth pixel in every other row.
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.TP 12
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\fBhourglass\fR
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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
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.QW 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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.PP
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In addition, the following pre-defined names are available only on the
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\fBMacintosh\fR platform:
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.TP 12
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\fBdocument\fR
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A generic document.
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.TP 12
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\fBstationery\fR
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Document stationery.
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.TP 12
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\fBedition\fR
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The \fIedition\fR symbol.
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.TP 12
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\fBapplication\fR
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Generic application icon.
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.TP 12
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\fBaccessory\fR
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A desk accessory.
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.TP 12
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\fBfolder\fR
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Generic folder icon.
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.TP 12
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\fBpfolder\fR
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A locked folder.
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.TP 12
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\fBtrash\fR
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A trash can.
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.TP 12
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\fBfloppy\fR
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A floppy disk.
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.TP 12
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\fBramdisk\fR
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A floppy disk with chip.
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.TP 12
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\fBcdrom\fR
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A cd disk icon.
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.TP 12
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\fBpreferences\fR
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A folder with prefs symbol.
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.TP 12
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\fBquerydoc\fR
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A database document icon.
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.TP 12
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\fBstop\fR
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A stop sign.
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.TP 12
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\fBnote\fR
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A face with balloon words.
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.TP 12
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\fBcaution\fR
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A triangle with an exclamation point.
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.RE
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.LP
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Under normal conditions, \fBTk_AllocBitmapFromObj\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 \fIobjPtr\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\fR's result if \fIinterp\fR is not
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NULL. \fBTk_AllocBitmapFromObj\fR caches information about the return
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value in \fIobjPtr\fR, which speeds up future calls to procedures
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such as \fBTk_AllocBitmapFromObj\fR and \fBTk_GetBitmapFromObj\fR.
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.PP
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\fBTk_GetBitmap\fR is identical to \fBTk_AllocBitmapFromObj\fR except
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that the description of the bitmap is specified with a string instead
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of an object. This prevents \fBTk_GetBitmap\fR from caching the
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return value, so \fBTk_GetBitmap\fR is less efficient than
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\fBTk_AllocBitmapFromObj\fR.
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.PP
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\fBTk_GetBitmapFromObj\fR returns the token for an existing bitmap, given
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the window and description used to create the bitmap.
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\fBTk_GetBitmapFromObj\fR does not actually create the bitmap; the bitmap
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must already have been created with a previous call to
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\fBTk_AllocBitmapFromObj\fR or \fBTk_GetBitmap\fR. The return
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value is cached in \fIobjPtr\fR, which speeds up
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future calls to \fBTk_GetBitmapFromObj\fR with the same \fIobjPtr\fR
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and \fItkwin\fR.
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.PP
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\fBTk_DefineBitmap\fR associates a name with
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in-memory bitmap data so that the name can be used in later
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calls to \fBTk_AllocBitmapFromObj\fR or \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 \fBTCL_OK\fR; if an error occurs
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(e.g. a bitmap named \fInameId\fR has already been defined) then
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\fBTCL_ERROR\fR is returned and an error message is left in
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interpreter \fIinterp\fR's result.
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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 does not 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_AllocBitmapFromObj\fR or
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\fBTk_GetBitmap\fR.
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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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.CS
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Pixmap bitmap;
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#include "stip.bitmap"
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Tk_DefineBitmap(interp, "foo", stip_bits,
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stip_width, stip_height);
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\&...
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bitmap = Tk_GetBitmap(interp, tkwin, "foo");
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.CE
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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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.CS
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Pixmap bitmap;
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bitmap = Tk_GetBitmap(interp, tkwin, "@stip.bitmap");
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.CE
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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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Tk maintains a database of all the bitmaps that are currently in use.
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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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When a bitmap is no longer used, Tk will release it automatically.
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This approach can substantially reduce server overhead, so
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\fBTk_AllocBitmapFromObj\fR and \fBTk_GetBitmap\fR should generally
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be used in preference to Xlib procedures like \fBXReadBitmapFile\fR.
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.PP
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The bitmaps returned by \fBTk_AllocBitmapFromObj\fR and \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 textual description that was
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passed to \fBTk_GetBitmap\fR when the bitmap was created.
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\fIBitmap\fR must have been the return value from a previous
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call to \fBTk_AllocBitmapFromObj\fR or \fBTk_GetBitmap\fR.
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.PP
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\fBTk_SizeOfBitmap\fR returns the dimensions of its \fIbitmap\fR
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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_AllocBitmapFromObj\fR or
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\fBTk_GetBitmap\fR.
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.PP
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When a bitmap is no longer needed, \fBTk_FreeBitmapFromObj\fR or
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\fBTk_FreeBitmap\fR should be called to release it.
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For \fBTk_FreeBitmapFromObj\fR the bitmap to release is specified
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with the same information used to create it; for
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\fBTk_FreeBitmap\fR the bitmap to release is specified
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with its Pixmap token.
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There should be exactly one call to \fBTk_FreeBitmapFromObj\fR
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or \fBTk_FreeBitmap\fR for each call to \fBTk_AllocBitmapFromObj\fR or
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\fBTk_GetBitmap\fR.
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.SH BUGS
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.PP
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In determining whether an existing bitmap can be used to satisfy
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a new request, \fBTk_AllocBitmapFromObj\fR and \fBTk_GetBitmap\fR
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consider only the immediate value of the string description. 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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