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April - June, 2008 Status Reports
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XAllocNamedColor() XAllocNamedColor()
Name
XAllocNamedColor - allocate a read-only colorcell from color name.
Synopsis
Status XAllocNamedColor(display, colormap, color_name, screen_def_return, exact_def_return)
Display *display;
Colormap colormap;
char *color_name;
XColor *screen_def_return;
XColor *exact_def_return;
Arguments
display Specifies a connection to an X server; returned from XOpenDisplay().
colormap Specifies the ID of the colormap in which the colorcell will be allocated.
color_name
Specifies the color name string (for example, "red") you want. Uppercase or lowercase does not matter. If the color name is not
in the Host Portable Character Encoding, the result is implementation-dependent.
screen_def_return
Returns the pixel value and RGB values actually used in the colormap. This is the closest color supported by the hardware.
exact_def_return
Returns the exact RGB values from the database corresponding to the color_name supplied.
Returns
Zero on failure, non-zero on success.
Description
XAllocNamedColor() determines the RGB values for the specified color_name from the color database, and then allocates a read-only colorcell
with the closest color available, as described under XAllocColor().
Like XAllocColor, XAllocNamedColor() acts differently on static and dynamic visuals. On PseudoColor, DirectColor, and GrayScale visuals,
XAllocNamedColor() fails if there are no unallocated colorcells and no allocated read-only colorcell exactly matches the database defini-
tion of the requested color. On StaticColor, TrueColor, and StaticGray visuals, XAllocNamedColor() returns the closest RGB values (to the
database definition of the requested color) available in the colormap. Both the database definition of the color, and the color actually
allocated are returned.
XAllocNamedColor() returns a Status of zero if color_name was not found in the database or if the color could not be allocated. The func-
tion returns non-zero when it succeeds.
For more information, see Volume One, Chapter 7, Color.
Errors
BadColor colormap is invalid.
Structures
typedef struct {
unsigned long pixel;
unsigned short red, green, blue;
char flags; /* DoRed, DoGreen, DoBlue */
char pad;
} XColor;
See Also
XBlackPixel(), XWhitePixel(), XAllocColor(), XAllocColorCells(), XAllocColorPlanes(), XFreeColors(), XLookupColor(), XParseColor(), XQuery-
Color(), XQueryColors(), XStoreColor(), XStoreColors(), XStoreNamedColor().
Xlib - Color Cells XAllocNamedColor()