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XcmsQueryColor, XcmsQueryColors, XcmsLookupColor - obtain color values
Status XcmsQueryColor(Display *display, Colormap colormap, XcmsColor *color_in_out, XcmsColorFormat result_format); Status XcmsQueryColors(Display *display, Colormap colormap, XcmsColor colors_in_out, unsigned int ncolors, XcmsColorFormat result_format); Status XcmsLookupColor(Display *display, Colormap colormap, char *color_string, XcmsColor *color_exact_return, XcmsColor *color_screen_return, XcmsColorFormat result_format);
display Specifies the connection to the X server. colormap Specifies the colormap. color_exact_return Returns the color specification parsed from the color string or parsed from the corresponding string found in a color-name database. color_in_out Specifies the pixel member that indicates the color cell to query. The color specification stored for the color cell is returned in this XcmsColor structure. color_screen_return Returns the color that can be reproduced on the screen. color_string Specifies the color string. result_format Specifies the color format for the returned color specifications (color_screen_return and color_exact_return arguments). If the format is XcmsUndefinedFormat and the color string contains a numerical color specification, the specification is returned in the format used in that numerical color specification. If the format is XcmsUndefinedFormat and the color string contains a color name, the specification is returned in the format used to store the color in the database. ncolors Specifies the number of XcmsColor structures in the color-specification array.
The XcmsQueryColor function obtains the RGB value for the pixel value in the pixel member of the specified XcmsColor structure and then converts the value to the target format as specified by the result_format argument. If the pixel is not a valid index in the specified colormap, a BadValue error results. The XcmsQueryColors function obtains the RGB values for pixel values in the pixel members of XcmsColor structures and then converts the values to the target format as specified by the result_format argument. If a pixel is not a valid index into the specified colormap, a BadValue error results. If more than one pixel is in error, the one that gets reported is arbitrary. XcmsQueryColor and XcmsQueryColors can generate BadColor and BadValue errors. The XcmsLookupColor function looks up the string name of a color with respect to the screen associated with the specified colormap. It returns both the exact color values and the closest values provided by the screen with respect to the visual type of the specified colormap. The values are returned in the format specified by result_format. If the color name is not in the Host Portable Character Encoding, the result is implementation- dependent. Use of uppercase or lowercase does not matter. XcmsLookupColor returns XcmsSuccess or XcmsSuccessWithCompression if the name is resolved; otherwise, it returns XcmsFailure. If XcmsSuccessWithCompression is returned, the color specification returned in color_screen_return is the result of gamut compression.
BadColor A value for a Colormap argument does not name a defined Colormap. BadValue Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted. Any argument defined as a set of alternatives can generate this error.
XcmsAllocColor(3), XcmsStoreColor(3), XQueryColor(3) Xlib - C Language X Interface