Game Programming using Qt 5 Beginner's Guide - Second Edition

Pens and brushes

The pen and brush are two attributes that define how different drawing operations are performed. The pen (represented by the QPen class) defines the outline, and the brush (represented by the QBrush class) fills the drawn shapes. Each of them is really a set of parameters. The most simple one is the color defined, either as a predefined global color enumeration value (such as Qt::red or Qt::transparent), or an instance of the QColor class. The effective color is made up of four attributes: three color components (red, green, and blue) and an optional alpha channel value that determines the transparency of the color (the larger the value, the more opaque the color). By default, all components are expressed as 8-bit values ...