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# QGLColormap Class Reference
[com.trolltech.qt.opengl module]

The `QGLColormap` class is used for installing custom colormaps into QGLWidgets. More...

## Detailed Description

The `QGLColormap` class is used for installing custom colormaps into QGLWidgets.

`QGLColormap` provides a platform independent way of specifying and installing indexed colormaps into QGLWidgets. `QGLColormap` is especially useful when using the OpenGL color-index mode.

Under X11 you must use an X server that supports either a `PseudoColor` or `DirectColor` visual class. If your X server currently only provides a `GrayScale`, `TrueColor`, `StaticColor` or `StaticGray` visual, you will not be able to allocate colorcells for writing. If this is the case, try setting your X server to 8 bit mode. It should then provide you with at least a `PseudoColor` visual. Note that you may experience colormap flashing if your X server is running in 8 bit mode.

Under Windows the size of the colormap is always set to 256 colors. Note that under Windows you can also install colormaps in child widgets.

This class uses implicit sharing as a memory and speed optimization.

Example of use:

        #include <QApplication>
        #include <QGLColormap>

        int main()
        {
            QApplication app(argc, argv);

            MySuperGLWidget widget;     // a QGLWidget in color-index mode
            QGLColormap colormap;

            // This will fill the colormap with colors ranging from
            // black to white.
            for (int i = 0; i < colormap.size(); i++)
                colormap.setEntry(i, qRgb(i, i, i));

            widget.setColormap(colormap);
            widget.show();
            return app.exec();
        }

See also `QGLWidget::setColormap` and `QGLWidget::colormap`.