RenderTargetBitmap + Resource'd VisualBrush = incomplete image
- by Will
I've found a new twist on the "Visual to RenderTargetBitmap" question!
I'm rendering previews of WPF stuff for a designer. That means I need to take a WPF visual and render it to a bitmap without that visual ever being displayed. Got a nice little method to do it like to see it here it goes
private static BitmapSource CreateBitmapSource(FrameworkElement visual)
{
Border b = new Border { Width = visual.Width, Height = visual.Height };
b.BorderBrush = Brushes.Black;
b.BorderThickness = new Thickness(1);
b.Background = Brushes.White;
b.Child = visual;
b.Measure(new Size(b.Width, b.Height));
b.Arrange(new Rect(b.DesiredSize));
RenderTargetBitmap rtb = new RenderTargetBitmap(
(int)b.ActualWidth,
(int)b.ActualHeight,
96,
96,
PixelFormats.Pbgra32);
// intermediate step here to ensure any VisualBrushes are rendered properly
DrawingVisual dv = new DrawingVisual();
using (var dc = dv.RenderOpen())
{
var vb = new VisualBrush(b);
dc.DrawRectangle(vb, null, new Rect(new Point(), b.DesiredSize));
}
rtb.Render(dv);
return rtb;
}
Works fine, except for one leeetle thing... if my FrameworkElement has a VisualBrush, that brush doesn't end up in the final rendered bitmap. Something like this:
<UserControl.Resources>
<VisualBrush
x:Key="LOLgo">
<VisualBrush.Visual>
<!-- blah blah -->
<Grid
Background="{StaticResource LOLgo}">
<!-- yadda yadda -->
Everything else renders to the bitmap, but that VisualBrush just won't show. The obvious google solutions have been attempted and have failed. Even the ones that specifically mention VisualBrushes missing from RTB'd bitmaps.
I have a sneaky suspicion this might be caused by the fact that its a Resource, and that lazy resource isn't being inlined. So a possible fix would be to, somehow(???), force resolution of all static resource references before rendering. But I have absolutely no idea how to do that.
Anybody have a fix for this?
