public override void BeforeRender(WpfDrawingRenderer renderer)
{
base.BeforeRender(renderer);
WpfDrawingContext context = renderer.Context;
Geometry clipGeom = this.ClipGeometry;
Transform transform = this.Transform;
SvgUseElement useElement = (SvgUseElement)_svgElement;
string elementId = this.GetElementName();
float opacityValue = -1;
string opacity = useElement.GetAttribute("opacity");
if (string.IsNullOrWhiteSpace(opacity))
{
opacity = useElement.GetPropertyValue("opacity");
}
if (!string.IsNullOrWhiteSpace(opacity))
{
opacityValue = (float)SvgNumber.ParseNumber(opacity);
opacityValue = Math.Min(opacityValue, 1);
opacityValue = Math.Max(opacityValue, 0);
}
_drawGroup = new DrawingGroup();
DrawingGroup currentGroup = context.Peek();
if (currentGroup == null)
{
throw new InvalidOperationException("An existing group is expected.");
}
currentGroup.Children.Add(_drawGroup);
context.Push(_drawGroup);
if (clipGeom != null || transform != null || (opacityValue >= 0 && opacityValue < 1) ||
(!string.IsNullOrWhiteSpace(elementId) && !context.IsRegisteredId(elementId)))
{
if (clipGeom != null)
{
_drawGroup.ClipGeometry = clipGeom;
}
if (transform != null)
{
_drawGroup.Transform = transform;
}
if (opacityValue >= 0 && opacityValue < 1)
{
_drawGroup.Opacity = opacityValue;
}
if (!string.IsNullOrWhiteSpace(elementId) && !context.IsRegisteredId(elementId))
{
SvgObject.SetName(_drawGroup, elementId);
context.RegisterId(elementId);
if (context.IncludeRuntime)
{
SvgObject.SetId(_drawGroup, elementId);
}
}
}
}