Index of Section 3 Manual Pages
| Interix / SUA | Tk_SizeOfBitmap.3 | Interix / SUA |
Tk_AllocBitmapFromObj(Tk Library ProcedurTk_AllocBitmapFromObj(3)
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NAME
Tk_AllocBitmapFromObj, Tk_GetBitmap, Tk_GetBitmapFromObj,
Tk_DefineBitmap, Tk_NameOfBitmap, Tk_SizeOfBitmap,
Tk_FreeBitmapFromObj, Tk_FreeBitmap - maintain database of
single-plane pixmaps
SYNOPSIS
#include
Pixmap |
Tk_AllocBitmapFromObj(interp, tkwin, objPtr) |
Pixmap |
Tk_GetBitmap(interp, tkwin, info) |
Pixmap |
Tk_GetBitmapFromObj(tkwin, objPtr) |
int
Tk_DefineBitmap(interp, name, source, width, height)
CONST char *
Tk_NameOfBitmap(display, bitmap)
Tk_SizeOfBitmap(display, bitmap, widthPtr, heightPtr)
Tk_FreeBitmapFromObj(tkwin, objPtr) |
Tk_FreeBitmap(display, bitmap)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use
for error reporting;
if NULL then no
error message is
left after errors.
Tk_Window tkwin (in) Token for window in
which the bitmap
will be used.
Tcl_Obj *objPtr (in/out) ||
String value |
describes desired |
bitmap; internal rep |
will be modified to |
cache pointer to |
corresponding |
Pixmap. |
CONST |
char *info (in) | |
Same as objPtr |
except description |
of bitmap is passed |
as a string and |
resulting Pixmap |
isn't cached.
CONST char *name (in) Name for new bitmap
to be defined.
CONST char *source (in) Data for bitmap, in
standard bitmap for-
mat. Must be stored
in static memory
whose value will
never change.
int width (in) Width of bitmap.
int height (in) Height of bitmap.
int *widthPtr (out) Pointer to word to
fill in with
bitmap's width.
int *heightPtr (out) Pointer to word to
fill in with
bitmap's height.
Display *display (in) Display for which
bitmap was allo-
cated.
Pixmap bitmap (in) Identifier for a
bitmap allocated by
Tk_AllocBitmapFro-
mObj or Tk_Get-
Bitmap.
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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_AllocBitmapFromObj returns a Pixmap identifier for a |
bitmap that matches the description in objPtr and is suit- |
able for use in tkwin. It re-uses an existing bitmap, if |
possible, and creates a new one otherwise. ObjPtr's value |
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.
gray75 ||
75% gray: a checkerboard |
pattern where three out of |
four bits are on.
gray50 50% gray: a checkerboard
pattern where every other
bit is on.
gray25 ||
25% gray: a checkerboard |
pattern where one out of |
every four bits is on.
gray12 12.5% gray: a pattern
where one-eighth of the
bits are on, consisting of
every fourth pixel in
every other row.
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.
warning A large exclamation point.
In addition, the following pre-defined
names are available only on the Macin-
tosh platform:
document A generic document.
stationery Document stationery.
edition The edition symbol.
application Generic application icon.
accessory A desk accessory.
folder Generic folder icon.
pfolder A locked folder.
trash A trash can.
floppy A floppy disk.
ramdisk A floppy disk with chip.
cdrom A cd disk icon.
preferences A folder with prefs sym-
bol.
querydoc A database document icon.
stop A stop sign.
note A face with ballon words.
caution A triangle with an excla-
mation point.
Under normal conditions, Tk_AllocBitmapFromObj returns an |
identifier for the requested bitmap. If an error occurs |
in creating the bitmap, such as when objPtr refers to a |
non-existent file, then None is returned and an error mes- |
sage is left in interp's result if interp isn't NULL. |
Tk_AllocBitmapFromObj caches information about the return |
value in objPtr, which speeds up future calls to proce- |
dures such as Tk_AllocBitmapFromObj and Tk_GetBitmapFro- |
mObj. |
Tk_GetBitmap is identical to Tk_AllocBitmapFromObj except |
that the description of the bitmap is specified with a |
string instead of an object. This prevents Tk_GetBitmap |
from caching the return value, so Tk_GetBitmap is less |
efficient than Tk_AllocBitmapFromObj. |
Tk_GetBitmapFromObj returns the token for an existing |
bitmap, given the window and description used to create |
the bitmap. Tk_GetBitmapFromObj doesn't actually create |
the bitmap; the bitmap must already have been created with |
a previous call to Tk_AllocBitmapFromObj or Tk_GetBitmap. |
The return value is cached in objPtr, which speeds up |
future calls to Tk_GetBitmapFromObj with the same objPtr |
and tkwin.
Tk_DefineBitmap associates a name with in-memory bitmap
data so that the name can be used in later calls to
Tk_AllocBitmapFromObj or Tk_GetBitmap. The nameId argu-
ment gives a name for the bitmap; it must not previously
have been used in a call to Tk_DefineBitmap. The argu-
ments 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 mem-
ory, but uses the bytes pointed to by source later in
calls to Tk_AllocBitmapFromObj or 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, "foo", stip_bits, |
stip_width, stip_height); |
... |
bitmap = Tk_GetBitmap(interp, tkwin, "foo"); |
This code causes the bitmap file to be read at compile-
time and incorporates the bitmap information into the pro-
gram's executable image. The same bitmap file could be
read at run-time using Tk_GetBitmap: |
Pixmap bitmap; |
bitmap = Tk_GetBitmap(interp, tkwin, "@stip.bitmap");|
The second form is a bit more flexible (the file could be
modified after the program has been compiled, or a differ-
ent 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 maintains a database of all the bitmaps that are cur-
rently in use. Whenever possible, it will return an
existing bitmap rather than creating a new one. When a
bitmap is no longer used, Tk will release it
automatically. This approach can substantially reduce
server overhead, so Tk_AllocBitmapFromObj and Tk_GetBitmap
should generally be used in preference to Xlib procedures
like XReadBitmapFile.
The bitmaps returned by Tk_AllocBitmapFromObj and Tk_Get-
Bitmap are shared, so callers should never modify them.
If a bitmap must be modified dynamically, then it should
be created by calling Xlib procedures such as XReadBitmap-
File or XCreatePixmap directly.
The procedure Tk_NameOfBitmap is roughly the inverse of
Tk_GetBitmap. Given an X Pixmap argument, it returns the
textual description that was passed to Tk_GetBitmap when
the bitmap was created. Bitmap must have been the return
value from a previous call to Tk_AllocBitmapFromObj or
Tk_GetBitmap.
Tk_SizeOfBitmap returns the dimensions of its bitmap argu-
ment in the words pointed to by the widthPtr and heightPtr
arguments. As with Tk_NameOfBitmap, bitmap must have been
created by Tk_AllocBitmapFromObj or Tk_GetBitmap.
When a bitmap is no longer needed, Tk_FreeBitmapFromObj or |
Tk_FreeBitmap should be called to release it. For |
Tk_FreeBitmapFromObj the bitmap to release is specified |
with the same information used to create it; for |
Tk_FreeBitmap the bitmap to release is specified with its |
Pixmap token. There should be exactly one call to |
Tk_FreeBitmapFromObj or Tk_FreeBitmap for each call to |
Tk_AllocBitmapFromObj or Tk_GetBitmap.
BUGS
In determining whether an existing bitmap can be used to
satisfy a new request, Tk_AllocBitmapFromObj and Tk_Get-
Bitmap consider only the immediate value of the string
description. 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
Tk 8.1 Tk_AllocBitmapFromObj(3)