GNU/Linux man pages
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GNU/Linux |
CentOS 2.1AS(Slurm) |
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GetBitmap(3) |
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Tk_AllocBitmapFromObj, Tk_GetBitmap, Tk_GetBitmapFromObj, Tk_DefineBitmap, Tk_NameOfBitmap, Tk_SizeOfBitmap, Tk_FreeBitmapFromObj, Tk_FreeBitmap, Tk_GetBitmapFromData − maintain database of single-plane pixmaps
#include <tk.h>
Pixmap
│
Tk_GetBitmapFromObj(interp, tkwin, objPtr)
│
Pixmap
│
Tk_GetBitmap(interp, tkwin, info)
│
Pixmap
│
Tk_GetBitmapFromObj(tkwin, objPtr)
│
int
Tk_DefineBitmap(interp, name, source, width,
height)
char *
Tk_NameOfBitmap(display, bitmap)
Tk_SizeOfBitmap(display, bitmap, widthPtr, heightPtr)
Tk_FreeBitmapFromObj(tkwin, objPtr) │
Tk_FreeBitmap(display, bitmap)
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Tcl_Interp *interp (in) |
Interpreter to use for error reporting; if NULL then no error message is left after errors. | ||
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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.
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CONST char *name (in) |
Name for new bitmap to be defined. | ||
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char *source (in) |
Data for bitmap, in standard bitmap format. Must be stored in static memory whose value will never change. | ||
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int width (in) |
Width of bitmap. | ||
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int height (in) |
Height of bitmap. | ||
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int *widthPtr (out) |
Pointer to word to fill in with bitmap’s width. | ||
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int *heightPtr (out) |
Pointer to word to fill in with bitmap’s height. | ||
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Display *display (in) |
Display for which bitmap was allocated. | ||
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Pixmap bitmap (in) |
Identifier for a bitmap allocated by Tk_AllocBitmapFromObj or Tk_GetBitmap. |
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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 suitable 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:
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@fileName |
FileName must be the name of a file containing a bitmap description in the standard X11 or X10 format. | ||
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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
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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.
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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.
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gray12 |
12.5% gray: a pattern where one-eighth of the bits are on, consisting of every fourth pixel in every other row. | ||
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hourglass |
An hourglass symbol. | ||
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info |
A large letter ’’i’’. | ||
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questhead |
The silhouette of a human head, with a question mark in it. | ||
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question |
A large question-mark. | ||
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warning |
A large exclamation point. |
In addition, the following pre-defined names are available only on the Macintosh platform:
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document |
A generic document. | ||
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stationery |
Document stationery. | ||
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edition |
The edition symbol. | ||
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application |
Generic application icon. | ||
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accessory |
A desk accessory. | ||
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folder |
Generic folder icon. | ||
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pfolder |
A locked folder. | ||
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trash |
A trash can. | ||
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floppy |
A floppy disk. | ||
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ramdisk |
A floppy disk with chip. | ||
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cdrom |
A cd disk icon. | ||
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preferences |
A folder with prefs symbol. | ||
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querydoc |
A database document icon. | ||
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stop |
A stop sign. | ||
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note |
A face with ballon words. | ||
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caution |
A triangle with an exclamation 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 message 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 procedures such as │ Tk_AllocBitmapFromObj and Tk_GetBitmapFromObj. │
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 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_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,
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stip_width, stip_height); │ |
... │
bitmap = Tk_GetBitmap(interp, tkwin, "foo");
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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,
"@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 maintains a database of all the bitmaps that are currently 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_GetBitmap 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 XReadBitmapFile 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 argument 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.
In determining whether an existing bitmap can be used to satisfy a new request, Tk_AllocBitmapFromObj and Tk_GetBitmap 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.
bitmap, pixmap
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GetBitmap(3) | |