QGLColormap Class Reference
[QtOpenGL module]

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().

Member Function Documentation

QGLColormap::QGLColormap ()

Construct a QGLColormap.

QGLColormap::QGLColormap ( const QGLColormap & map )

Construct a shallow copy of map.

QGLColormap::~QGLColormap ()

Dereferences the QGLColormap and deletes it if this was the last reference to it.

QColor QGLColormap::entryColor ( int idx ) const

Returns the QRgb value in the colorcell with index idx.

QRgb QGLColormap::entryRgb ( int idx ) const

Returns the QRgb value in the colorcell with index idx.

int QGLColormap::find ( QRgb color ) const

Returns the index of the color color. If color is not in the map, -1 is returned.

int QGLColormap::findNearest ( QRgb color ) const

Returns the index of the color that is the closest match to color color.

bool QGLColormap::isEmpty () const

Returns true if the colormap is empty; otherwise returns false. A colormap with no color values set is considered to be empty.

void QGLColormap::setEntries ( int count, const QRgb * colors, int base = 0 )

Set an array of cells in this colormap. count is the number of colors that should be set, colors is the array of colors, and base is the starting index.

void QGLColormap::setEntry ( int idx, QRgb color )

Set cell at index idx in the colormap to color color.

void QGLColormap::setEntry ( int idx, const QColor & color )

This is an overloaded function.

Set the cell with index idx in the colormap to color color.

int QGLColormap::size () const

Returns the number of colorcells in the colormap.

QGLColormap & QGLColormap::operator= ( const QGLColormap & map )

Assign a shallow copy of map to this QGLColormap.