/// <summary>
/// Obtains the current bounds of the brush's content
/// </summary>
/// <param name="contentBounds"> Output bounds of content</param>
protected override void GetContentBounds(out Rect contentBounds)
{
// Obtain the current visual's outer space bounding box. We return the outer space
// bounding box because we want to have the bounding box of the Visual tree including
// transform/offset at the root.
if (_isCacheDirty)
{
_bbox = Visual.CalculateSubgraphBoundsOuterSpace();
_isCacheDirty = false;
}
contentBounds = _bbox;
}
