void pushClipRect(bool needsCompositing, Offset offset, Rect clipRect, PaintingContextCallback painter)

Clip further painting using a rectangle.

  • 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.
  • clipRect is rectangle (in the caller's coodinate system) to use to clip the painting done by painter.
  • painter is a callback that will paint with the clipRect applied. This function calls the painter synchronously.

Source 

void pushClipRect(bool needsCompositing, Offset offset, Rect clipRect, PaintingContextCallback painter) {
  final Rect offsetClipRect = clipRect.shift(offset);
  if (needsCompositing) {
    _stopRecordingIfNeeded();
    final ClipRectLayer clipLayer = new ClipRectLayer(clipRect: offsetClipRect);
    _appendLayer(clipLayer);
    final PaintingContext childContext = new PaintingContext._(clipLayer, offsetClipRect);
    painter(childContext, offset);
    childContext._stopRecordingIfNeeded();
  } else {
    canvas.save();
    canvas.clipRect(offsetClipRect);
    painter(this, offset);
    canvas.restore();
  }
}