reset method
Implementation
void reset([Matrix? matrix, num? alpha, BlendMode? blendMode]) {
final currentContextState = _currentContextState = _firstContextState;
currentContextState.matrix.identity();
currentContextState.alpha = 1.0;
currentContextState.blendMode = BlendMode.NORMAL;
if (matrix is Matrix) _firstContextState.matrix.copyFrom(matrix);
if (alpha is num) _firstContextState.alpha = alpha.toDouble();
if (blendMode is BlendMode) _firstContextState.blendMode = blendMode;
}