Expression qt.QBrush(table) returns a brush whose settings
are determined by the fields of table table.
The following fields are recognized:
color contains a qt.QColor value
representing the brush color.
texture contains a qt.QImage value
representing the brush texture.
gradient contains a qt.QGradient value
representing a color gradient.
transform contains a qt.QTransform value that
defines a additional transformation applied to the brush before
painting it into the current coordinate system.
style contains the name of the
brush style.
The default brush style is SolidPatter when field color is defined,
TexturePattern when field texture is defined, or one of the gradient styles
when field gradient is defined. Otherwise the default style is NoBrush
meaning that nothing is painted.