DropShadowBitmapEffect Doesn't work on TextBlock

Question

Does anyone know why the DropShadowBitmapEffect and the EmbossBitmapEffect won't work on a TextBlock (not textBOX) in WPF? OuterGlow, Blur and Bevel seem to work fine.

Answer 1

Bitmap effects work by looking at the post-rendered pixels and running standard image manipulation on them. It should only be dependent on the color of the pixels. I wonder if their algorithms don't work well on white. Try changing the color to see if that has an effect -- if it does, you might want to try putting a black panel underneath with drop shadow set on it.

Edit: The questioner found the answer

"Thanks for pointing me in the correct general direction. It wasn't the color of the text or the DropShadow that mattered, what is needed is to make the Background Brush on the TextBlock the Transparent Brush (Alpha = 0) instead of null."

Answer 2

The transparent background brush is apparently not the answer because you can get a dropshadow with a null background brush. The default softness on a dropshadow is 50% and if you have a small font, the softness dissipates the shadow too much. There seems to be a steep drop off around softness of 39% (at which point the shadow more or less disappears). Try setting it to 0 and slowly moving you're way up until you find a number that still shows the shadow.

Answer 3

The background brush = transparent solution still may work for the embossing effect

Answer 4

Important Sidenote: you shouldn't really be using BitmapEffects any more. Use the Effect property based on ShaderModel effects introduced in .net 3.5 SP1, it uses hardware rendering and has far better performance.

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Answer 5

Yet another note: the softness is definitely a factor, but be aware in Xaml the valid values are really only 0 to 1, but in Blend it shows it as a percentage up to 100. So if you set the value to 100 in Xaml, it will be completely dissipated.