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Tk_GetVisual(3) Tk Library Procedures Tk_GetVisual(3) ______________________________________________________________________________ NAME Tk_GetVisual - translate from string to visual SYNOPSIS #include <tk.h> Visual * Tk_GetVisual(interp, tkwin, string, depthPtr, colormapPtr) ARGUMENTS Tcl_Interp *interp (in) Interpreter to use for error re- porting. Tk_Window tkwin (in) Token for window in which the vi- sual will be used. const char *string (in) String that identifies the de- sired visual. See below for valid formats. int *depthPtr (out) Depth of returned visual gets stored here. Colormap *colormapPtr (out) If non-NULL then a suitable col- ormap for visual is found and its identifier is stored here. ______________________________________________________________________________ DESCRIPTION Tk_GetVisual takes a string description of a visual and finds a suit- able X Visual for use in tkwin, if there is one. It returns a pointer to the X Visual structure for the visual and stores the number of bits per pixel for it at *depthPtr. If string is unrecognizable or if no suitable visual could be found, then NULL is returned and Tk_GetVisual leaves an error message in interpreter interp's result. If colormap is non-NULL then Tk_GetVisual also locates an appropriate colormap for use with the result visual and stores its X identifier at *colormapPtr. The string argument specifies the desired visual in one of the follow- ing ways: class depth The string consists of a class name followed by an inte- ger depth, with any amount of white space (including none) in between. class selects what sort of visual is desired and must be one of directcolor, grayscale, greyscale, pseudocolor, staticcolor, staticgray, static- grey, or truecolor, or a unique abbreviation. depth specifies how many bits per pixel are needed for the vi- sual. If possible, Tk_GetVisual will return a visual with this depth; if there is no visual of the desired depth then Tk_GetVisual looks first for a visual with greater depth, then one with less depth. default Use the default visual for tkwin's screen. pathName Use the visual for the window given by pathName. path- Name must be the name of a window on the same screen as tkwin. number Use the visual whose X identifier is number. best ?depth? Choose the "best possible" visual, using the following rules, in decreasing order of priority: (a) a visual that has exactly the desired depth is best, followed by a visual with greater depth than requested (but as little extra as possible), followed by a visual with less depth than re- quested (but as great a depth as possible); (b) if no depth is specified, then the deepest avail- able visual is chosen; (c) pseudocolor is better than truecolor or direct- color, which are better than staticcolor, which is better than staticgray or grayscale; (d) the default visual for the screen is better than any other visual. CREDITS The idea for Tk_GetVisual, and the first implementation, came from Paul Mackerras. KEYWORDS colormap, screen, visual Tk 4.0 Tk_GetVisual(3)
NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | CREDITS | KEYWORDS
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