- NAME
- Tk_GetVisual — translate from string to visual
- SYNOPSIS
- #include <tk.h>
- Visual *
- Tk_GetVisual(interp, tkwin, string, depthPtr,
colormapPtr)
- ARGUMENTS
- DESCRIPTION
- class
depth
- default
- pathName
- number
- best
?depth?
- CREDITS
- KEYWORDS
Tk_GetVisual — translate from string to visual
#include <tk.h>
Visual *
Tk_GetVisual(interp, tkwin, string, depthPtr,
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.
- 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.
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 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 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 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);
- if no depth is specified, then the deepest
available visual is chosen;
- pseudocolor is better than truecolor or
directcolor, which are better than staticcolor, which
is better than staticgray or grayscale;
- the default visual for the screen is better than any
other visual.
The idea for Tk_GetVisual, and the first implementation,
came from Paul Mackerras.
colormap, screen, visual
Copyright © 1994 The Regents of the University of
California.
Copyright © 1994-1996 Sun Microsystems, Inc.