Qt color define

Predefined Colors

There are 20 predefined QColors described by the  Qt::GlobalColor  enum, including black, white, primary and secondary colors, darker versions of these colors and three shades of gray. QColor also recognizes a variety of color names; the static  colorNames () function returns a  QStringList  color names that QColor knows about.

Additionally, the Qt::color0, Qt::color1 and Qt::transparent colors are used for special purposes.

Qt::color0 (zero pixel value) and Qt::color1 (non-zero pixel value) are special colors for drawing in QBitmaps. Painting with Qt::color0 sets the bitmap bits to 0 (transparent; i.e., background), and painting with Qt::color1 sets the bits to 1 (opaque; i.e., foreground).

Qt::transparent is used to indicate a transparent pixel. When painting with this value, a pixel value will be used that is appropriate for the underlying pixel format in use.

QColor::QColor ( int r, int g, int b, int a = 255 )

Constructs a color with the RGB value r, g, b, and the alpha-channel (transparency) value of a.

The color is left invalid if any of the arguments are invalid.