SHOWRGB(1) General Commands Manual SHOWRGB(1)NAME
showrgb - display an rgb color-name database
SYNOPSIS
showrgb [ database ]
DESCRIPTION
The showrgb program reads an rgb color-name database from a text file and converts it back to source form, printing the result to standard
output. The default database is the one that X was built with, and may be overridden on the command line. Specify the database name with-
out the .txt, .pag or .dir suffix.
FILES
/usr/share/X11/rgb default database.
X Version 11 rgb 1.0.4 SHOWRGB(1)
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XLookupColor() XLookupColor()
Name
XLookupColor - get database RGB values and closest hardware-supported RGB values from color name.
Synopsis
Status XLookupColor(display, colormap, colorname, exact_def_return, screen_def_return)
Display *display;
Colormap colormap;
char *colorname;
XColor *exact_def_return, *screen_def_return;
Arguments
display Specifies a connection to an X server; returned from XOpenDisplay().
colormap Specifies the colormap.
colorname Specifies a color name string (for example "red"). Uppercase or lowercase does not matter. If the color name is not in the
Host Portable Character Encoding, the result is implementation-dependent.
exact_def_return
Returns the exact RGB values for the specified color name from the /usr/lib/X11/rgb database.
screen_def_return
Returns the closest RGB values possible on the hardware.
Returns
Zero on failure, non-zero on success.
Description
XLookupColor() looks up RGB values for a color given the colorname string. It returns both the exact color values and the closest values
possible on tthe screen specified by colormap.
XLookupColor() returns non-zero if colorname exists in the RGB database or zero if it does not exist.
To determine the exact RGB values, XLookupColor() uses a database on the X server. On UNIX, this database is /usr/lib/X11/rgb. To read
the colors provided by the database on a UNIX-based system, see /usr/lib/X11/rgb.txt. The location, name, and contents of this file are
server-dependent.
For more information see Volume One, Chapter 7, Color, and Appendix D, The Server-side Color Database, in this volume.
Errors
BadName Color name not in database.
BadColor Invalid colormap.
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(), XAllocNamedColor(), XFreeColors(), XParseColor(),
XQueryColor(), XQueryColors(), XStoreColor(), XStoreColors(), XStoreNamedColor().
Xlib - Color Cells XLookupColor()