HPUX GetBitmap[3]
GetBitmap in anderen Kapiteln des hpux Handbuch:
Tk_GetBitmap(3) Tk Tk_GetBitmap(3)
Tk Library Procedures Tk Library Procedures
___________________________________________________________________________
NAME
Tk_GetBitmap, Tk_DefineBitmap, Tk_NameOfBitmap, Tk_SizeOfBitmap,
Tk_FreeBitmap, Tk_GetBitmapFromData - maintain database of single-
plane pixmaps
SYNOPSIS
#include <tk.h>
Pixmap
Tk_GetBitmap(interp, tkwin, id)
int |
Tk_DefineBitmap(interp, nameId, source, width, height) |
Tk_Uid
Tk_NameOfBitmap(display, bitmap) |
Tk_SizeOfBitmap(display, bitmap, widthPtr, heightPtr) |
Tk_FreeBitmap(display, bitmap) |
ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use for error
reporting.
Tk_Window tkwin (in) Token for window in which the
bitmap will be used.
Tk_Uid id (in) Description of bitmap; see
below for possible values.
Tk_Uid *nameId (in) Name for new bitmap to be
defined.
char *source (in) Data for bitmap, in standard
bitmap format. Must be stored
in static memory whose value
will never change.
unsigned int width (in) Width of bitmap.
unsigned int height (in) Height of bitmap.
unsigned int *widthPtr (out) Pointer to word to fill in with
bitmap's width.
unsigned int *heightPtr (out) Pointer to word to fill in with
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Tk_GetBitmap(3) Tk Tk_GetBitmap(3)
Tk Library Procedures Tk Library Procedures
bitmap's height.
Display *display (in) Display for which bitmap was
allocated. |
Pixmap bitmap (in) Identifier for a bitmap
allocated by Tk_GetBitmap.
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DESCRIPTION
These procedures manage a collection of bitmaps (one-plane pixmaps)
being used by an application. The procedures allow bitmaps to be re-
used efficiently, thereby avoiding server overhead, and also allow
bitmaps to be named with character strings.
Tk_GetBitmap takes as argument a Tk_Uid describing a bitmap. It
returns a Pixmap identifier for a bitmap corresponding to the
description. It re-uses an existing bitmap, if possible, and creates
a new one otherwise. At present, id must have one of the following
forms:
@fileName FileName must be the name of a file containing a
bitmap description in the standard X11 or X10
format.
name Name must be the name of a bitmap defined
previously with a call to Tk_DefineBitmap. The
following names are pre-defined by Tk:
error The international "don't" symbol: a |
circle with a diagonal line across it. |
gray50 50% gray: a checkerboard pattern where
every other bit is on.
gray25 25% gray: a pattern where 25% of the
bits are on, consisting of all the bit
positions that can be reached by a
chess knight starting at (0,0).
hourglass An hourglass symbol. |
info A large letter ``i''. |
questhead The silhouette of a human head, with a |
question mark in it. |
question A large question-mark. |
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Tk_GetBitmap(3) Tk Tk_GetBitmap(3)
Tk Library Procedures Tk Library Procedures
warning A large exclamation point. |
Under normal conditions, Tk_GetBitmap returns an identifier for the
requested bitmap. If an error occurs in creating the bitmap, such as
when id refers to a non-existent file, then None is returned and an
error message is left in interp->result.
Tk_DefineBitmap associates a name with in-memory bitmap data so that |
the name can be used in later calls to Tk_GetBitmap. The nameId |
argument gives a name for the bitmap; it must not previously have |
been used in a call to Tk_DefineBitmap. The arguments source, width, |
and height describe the bitmap. Tk_DefineBitmap normally returns |
TCL_OK; if an error occurs (e.g. a bitmap named nameId has already |
been defined) then TCL_ERROR is returned and an error message is left |
in interp->result. Note: Tk_DefineBitmap expects the memory pointed |
to by source to be static: Tk_DefineBitmap doesn't make a private |
copy of this memory, but uses the bytes pointed to by source later in |
calls to Tk_GetBitmap. |
Typically Tk_DefineBitmap is used by #include-ing a bitmap file
directly into a C program and then referencing the variables defined
by the file. For example, suppose there exists a file stip.bitmap,
which was created by the bitmap program and contains a stipple
pattern. The following code uses Tk_DefineBitmap to define a new
bitmap named foo:
Pixmap bitmap;
#include "stip.bitmap"
Tk_DefineBitmap(interp, Tk_GetUid("foo"), stip_bits,
stip_width, stip_height);
...
bitmap = Tk_GetBitmap(interp, tkwin, Tk_GetUid("foo"));
This code causes the bitmap file to be read at compile-time and
incorporates the bitmap information into the program's executable
image. The same bitmap file could be read at run-time using
Tk_GetBitmap:
Pixmap bitmap;
bitmap = Tk_GetBitmap(interp, tkwin, Tk_GetUid("@stip.bitmap"));
The second form is a bit more flexible (the file could be modified
after the program has been compiled, or a different string could be
provided to read a different file), but it is a little slower and
requires the bitmap file to exist separately from the program.
Tk_GetBitmap maintains a database of all the bitmaps that have been
created. Whenever possible, it will return an existing bitmap rather
than creating a new one. This approach can substantially reduce
server overhead, so Tk_GetBitmap should generally be used in
preference to Xlib procedures like XReadBitmapFile.
The bitmaps returned by Tk_GetBitmap are shared, so callers should
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Tk_GetBitmap(3) Tk Tk_GetBitmap(3)
Tk Library Procedures Tk Library Procedures
never modify them. If a bitmap must be modified dynamically, then it
should be created by calling Xlib procedures such as XReadBitmapFile
or XCreatePixmap directly.
The procedure Tk_NameOfBitmap is roughly the inverse of Tk_GetBitmap.
Given an X Pixmap argument, it returns the id that was passed to
Tk_GetBitmap when the bitmap was created. Bitmap must have been the |
return value from a previous call to Tk_GetBitmap. |
Tk_SizeOfBitmap returns the dimensions of its bitmap argument in the |
words pointed to by the widthPtr and heightPtr arguments. As with |
Tk_NameOfBitmap, bitmap must have been created by Tk_GetBitmap. |
When a bitmap returned by Tk_GetBitmap is no longer needed,
Tk_FreeBitmap should be called to release it. There should be exactly
one call to Tk_FreeBitmap for each call to Tk_GetBitmap. When a
bitmap is no longer in use anywhere (i.e. it has been freed as many
times as it has been gotten) Tk_FreeBitmap will release it to the X
server and delete it from the database.
BUGS
In determining whether an existing bitmap can be used to satisfy a new
request, Tk_GetBitmap considers only the immediate value of its id
argument. For example, when a file name is passed to Tk_GetBitmap,
Tk_GetBitmap will assume it is safe to re-use an existing bitmap
created from the same file name: it will not check to see whether the
file itself has changed, or whether the current directory has changed,
thereby causing the name to refer to a different file.
KEYWORDS
bitmap, pixmap
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