XAllocColor()XAllocColor()Name
XAllocColor – allocate a read-only colormap cell with closest hardware-
supported color.
Synopsis
Status XAllocColor(display, colormap, colorcell_in_out)
Display *display;
Colormap colormap;
XColor *colorcell_in_out;
Arguments
display Specifies a connection to an X server; returned from XOpenDis‐
play().
colormap
Specifies the ID of the colormap in which the colorcell is to
be allocated.
colorcell_in_out
Specifies desired RGB values, and also returns the pixel value
and the RGB values actually used in the colormap.
Returns
Zero on failure, non-zero on success.
DescriptionXAllocColor() returns the pixel value of a read-only (shareable) color‐
cell. The requested RGB values are placed in colorcell_in_out, which
is also used to return the allocated pixel value and the actual RGB
values of that colorcell. If XAllocColor() succeeds, it returns non-
zero. If it fails, it returns zero.
XAllocColor() acts differently on static and dynamic visuals. On Pseu‐
doColor, DirectColor, and GrayScale visuals, XAllocColor() fails if
there are no unallocated colorcells and no allocated read-only cell
exactly matches the requested RGB values. On StaticColor, TrueColor,
and StaticGray visuals, XAllocColor() returns the closest RGB values
available in the colormap. The colorcell_in_out structure returns the
actual RGB values allocated.
XAllocColor() does not use or affect the flags member of the XColor
structure.
For more information, see Volume One, Chapter 7, Color.
Structures
typedef struct {
unsigned long pixel;
unsigned short red, green, blue;
char flags; /* DoRed, DoGreen, DoBlue */
char pad;
} XColor;
Errors
BadColor colormap is invalid.
See AlsoXBlackPixel(), XWhitePixel(), XAllocColorCells(), XAllocColorPlanes(),
XAllocNamedColor(), XFreeColors(), XLookupColor(), XParseColor(),
XQueryColor(), XQueryColors(), XStoreColor(), XStoreColors(), XStore‐
NamedColor().
Xlib - Color Cells XAllocColor()
