pushTransform method

void pushTransform (bool needsCompositing, Offset offset, Matrix4 transform, PaintingContextCallback painter)

Transform further painting using a matrix.

  • needsCompositing is whether the child needs compositing. Typically matches the value of RenderObject.needsCompositing for the caller.
  • offset is the offset from the origin of the canvas' coordinate system to the origin of the caller's coordinate system.
  • transform is the matrix to apply to the painting done by painter.
  • painter is a callback that will paint with the transform applied. This function calls the painter synchronously.

Implementation 

void pushTransform(bool needsCompositing, Offset offset, Matrix4 transform, PaintingContextCallback painter) {
  final Matrix4 effectiveTransform = Matrix4.translationValues(offset.dx, offset.dy, 0.0)
    ..multiply(transform)..translate(-offset.dx, -offset.dy);
  if (needsCompositing) {
    pushLayer(
      TransformLayer(transform: effectiveTransform),
      painter,
      offset,
      childPaintBounds: MatrixUtils.inverseTransformRect(effectiveTransform, estimatedBounds),
    );
  } else {
    canvas
      ..save()
      ..transform(effectiveTransform.storage);
    painter(this, offset);
    canvas
      ..restore();
  }
}