You could use a BitmapCache
to create a bitmap that caches the rendering of the DrawingVisual
...so that when your FrameworkElement
is invalided (due to the sizing) the cached bitmap is used to provide the "visual bits", instead of the slower route of having to render the drawing instructions inside of the "DrawingVisual" again (i.e. what was described by StreamGeometry
in the drawingcontext).
DrawingVisual CreateDrawingVisualRectangle()
{
var drawingVisual = new DrawingVisual();
var drawingContext = drawingVisual.RenderOpen();
var geometry = new StreamGeometry();
using (var ctx = geometry.Open())
{
ctx.BeginFigure(new Point(0, 0), false, false);
var r = new Random();
for (int i = 0; i < 500; ++i)
{
var p1 = new Point(r.Next(0, 1000), r.Next(0, 1000));
var p2 = new Point(r.Next(0, 1000), r.Next(0, 1000));
ctx.QuadraticBezierTo(p1, p2, true, false);
}
}
geometry.Freeze();
drawingContext.DrawGeometry(null, new Pen(Brushes.Red, 1), geometry);
drawingContext.Close();
drawingVisual.CacheMode = new BitmapCache();
return drawingVisual;
}