- Tk_GetVisual - translate from string to visual
- class depth
- best ?depth?
Tk_GetVisual - translate from string to visual
Tk_GetVisual(interp, tkwin, string, depthPtr, colormapPtr)
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.
- Tcl_Interp *interp (in)
Interpreter to use for error reporting.
- Tk_Window tkwin (in)
Token for window in which the visual will be used.
- char *string (in)
String that identifies the desired visual. See below for
- 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.
The string argument specifies the desired visual in one
of the following ways:
The idea for Tk_GetVisual, and the first implementation, came
from Paul Mackerras.
colormap, screen, visual
- 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
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
Use the default visual for tkwin's screen.
Use the visual for the window given by pathName.
pathName must be the name of a window on the same screen
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
(c) pseudocolor is better than truecolor or directcolor,
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.
Copyright © 1994 The Regents of the University of California.
Copyright © 1994-1996 Sun Microsystems, Inc.
Copyright © 1995-1997 Roger E. Critchlow Jr.