ShaderMaskLayer constructor

ShaderMaskLayer({@required Shader shader, @required Rect maskRect, @required BlendMode blendMode })

Creates a shader mask layer.

The shader, maskRect, and blendMode properties must be non-null before the compositing phase of the pipeline.

Implementation 

ShaderMaskLayer({ @required Shader shader, @required Rect maskRect, @required BlendMode blendMode })
    : _shader = shader, _maskRect = maskRect, _blendMode = blendMode;