WPF Architecture and Direct3D graphics acceleration

Question

After reading the wikipedia article on WPF architecture, I am a bit confused with the benefits that WPF will offer me. (wikipedia is not a good research reference, but i found it useful). I have some questions

1) WPF uses d3d surfaces to render. However, the scenegraph is rendered into the d3d surface by the media integrated layer, which runs on the CPU. Is this true ?

2) I just found out by asking a question here that bitmaps dont use native resources. Does this mean that if i use alot of images, the MIL will copy each when rendering, rather than storing the bitmaps on the video card as a texture ?

3) The article mentions that WPF uses the painters algorithm which is back to front. Thats painfully slow. Is there any rational why WPF omits using Z-buffering and rendering front to back ? I am guessing its because the simplest way to handle transparency, but it seems weak.

The reason i ask is that i am thinking it wont be wise for me to put hundreds of buttons on a screen even though my colleagues are saying its directx accelerated. I dont quite believe that whole directx accelerated bit about WPF. I used to work on video games and my memory of writing d3d and opengl code tells me to be cautious.

Answer 1

For questions #1 and #3 you might want to check out this section of the SDK that discusses the Visual class and how it's rendering instructions are exchanged between the higher level framework and the media integration layer (MIL). It also discusses why the painters algorithm is used.

For #2, no that is most definitely not the case. The bitmap data will be moved to the hardware and cached there.

Answer 2

I tested that, I wrote two programs that show 1,000 buttons on screen, one in WinForms and one in WPF, both worked just fine.

I then pushed that up to 10,000 buttons, at that point the WPF app took a few seconds to start but run just fine, the WinForms app didn't start.

Win32 itself (and WinForms) isn't built for applications with hundreds of controls (believe me I wrote such an app), at some point it just stops working, WPF on the other hand, keeps working even if it slows down a bit at some point.

So, if you do need to put a lot of controls on screen WPF is your best bet (unless you want to roll your own UI framework - and you think you can do better than the entire MS perf team).

Also, WPF has many advantages other than graphics acceleration: richer graphics, drawing model that is easier to work with, animations, 3d and my personal favorite - amazing data-binding.

This will let you develop richer UIs faster - and I think that will make a much bigger difference than the painting algorithm used.

BTW, if you need to put hundreds of buttons on the screen this is likely to be a bad user experience and you may want to reconsider your UI design,