XSetStandar.3X() XSetStandar.3X()
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XSetStandardColormap XSetStandaA
XSetStandardProperties XSetStandaB
XSetStandar.3X()
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XSetStandardColormap(3X11)XSetStandardColormap(3X11)Name
XSetStandardColormap, XGetStandardColormap - set or get standard colormaps
Syntax
XSetStandardColormap(display, w, colormap, property)
Display *display;
Window w;
XStandardColormap *colormap;
Atom property; /* RGB_BEST_MAP, etc. */
Status XGetStandardColormap(display, w, colormap_return, property)
Display *display;
Window w;
XStandardColormap *colormap_return;
Atom property; /* RGB_BEST_MAP, etc. */
Arguments
colormap Specifies the colormap.
colormap_return
Returns the colormap associated with the specified atom.
display Specifies the connection to the X server.
property Specifies the property name.
w Specifies the window.
Description
The function usually is only used by window managers. To create a standard colormap, follow this procedure:
1. Open a new connection to the same server.
2. Grab the server.
3. See if the property is on the property list of the root window for the screen.
4. If the desired property is not present:
o Create a colormap (not required for RGB_DEFAULT_MAP)
o Determine the color capabilities of the display.
o Call or to allocate cells in the colormap.
o Call to store appropriate color values in the colormap.
o Fill in the descriptive members in the structure.
o Attach the property to the root window.
o Use to make the resource permanent.
5. Ungrab the server.
can generate and errors.
The function returns the colormap definition associated with the atom supplied as the property argument. For example, to fetch the stan-
dard colormap for a display, you use with the following syntax:
XGetStandardColormap(dpy, DefaultRootWindow(dpy), &cmap, XA_RGB_GRAY_MAP);
Once you have fetched a standard colormap, you can use it to convert RGB values into pixel values. For example, given an structure and
floating-point RGB coefficients in the range 0.0 to 1.0, you can compose pixel values with the following C expression:
pixel = base_pixel
+ ((unsigned long) (0.5 + r * red_max)) * red_mult
+ ((unsigned long) (0.5 + g * green_max)) * green_mult
+ ((unsigned long) (0.5 + b * blue_max)) * blue_mult;
The use of addition rather than logical OR for composing pixel values permits allocations where the RGB value is not aligned to bit bound-
aries.
can generate and errors.
Diagnostics
The server failed to allocate the requested resource or server memory.
A value for an Atom argument does not name a defined Atom.
A value for a Window argument does not name a defined Window.
See Also
Guide to the Xlib Library
XSetStandardColormap(3X11)