Tk_GetVisual(3) 					       Tk Library Procedures						   Tk_GetVisual(3)

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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 reporting.

       Tk_Window tkwin (in)		     Token for window in which the visual will be used.

       const char *string (in)		     String that identifies the desired 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 colormap for visual is found and its identifier is stored here.
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DESCRIPTION

       Tk_GetVisual  takes a string description of a visual and finds a suitable 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 interp->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 following ways:

       class depth    The string consists of a class name followed by an integer 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, staticgrey, or truecolor, or a unique abbreviation.  depth specifies how many bits  per	pixel  are
		      needed for the visual.  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.	pathName 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 requested (but as great a depth as possible);

		      (b)    if no depth is specified, then the deepest available visual is chosen;

		      (c)    pseudocolor  is  better  than truecolor or directcolor, which are better than staticcolor, which is better than stat-
			     icgray 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)