AllocCol(3X) — DeltaWindows 1.3.3 Release 4 Version 4.3

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

displaySpecifies a connection to an X server; returned from XOpenDisplay().

colormapSpecifies 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.

DESCRIPTION

XAllocColor() returns the pixel value of a read-only (shareable) colorcell. 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 PseudoColor, 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

BadColorcolormap is invalid.

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