What’s wrong with this code, Part 22 – the answers

re: What’s wrong with this code, Part 22 – the answers

Larry Osterman [MSFT] — Thu, 07 Aug 2008 01:43:09 GMT

Sys64738: Two words: "Managed Code". There are severe architectural layering issues with using extremely high level components like WPF. Server administrators will get hideously upset if they had to get WPF on their server machines just because the volume control UI used it.

The CLR team is improving things regularly and there is more and more managed code in Windows but the vast majority of Windows code is unmanaged.

re: What’s wrong with this code, Part 22 – the answers

Sys64738 — Thu, 07 Aug 2008 01:23:02 GMT

Hi Larry,

why don't you use a WPF-like technology in Windows UI?

I think that WPF is based on Direct3D (which is a native technology), with an interface layer to export native D3D stuff to managed world (maybe you use C++/CLI ?). So I wonder: what about using some kind of "WPF" in a 100% native context i.e. Direct3D *hardware accelerated rendering* using a *declarative* approach (like WPF does) for Windows UI?

...Performance reasons?

BTW: Thank you for your interesting blog posts! (Especially this "What's wrong in code" series - they help us learning a lot).

Regards

re: What’s wrong with this code, Part 22 – the answers

Larry Osterman [MSFT] — Tue, 05 Aug 2008 18:05:40 GMT

Ben: Raymond Chen just sent me an email suggesting the same thing. I hadn't realized that DT_CALCRECT would suppress drawing.

re: What’s wrong with this code, Part 22 – the answers

anony.muos — Tue, 05 Aug 2008 17:05:09 GMT

Hey Larry,

This is unrelated but please answer this. What ASUS seem have done is they've implemented DS3D in software as part of their Xonar drivers and MS's latest effort XAudio 2 also is a software-based DSP/surround sound solution however it's RTM in March isn't well publicized by MS, as a result, very few developers are aware of it or use it. My question is technically, would it have been possible for Microsoft to implement DS3D in software so that all the surround effects would have worked? If so, if there were time constraints with Windows Vista, why can't the same be achieved with Windows 7? Or is it not technically possible with the new audio stack?

re: What’s wrong with this code, Part 22 – the answers

Dave — Tue, 05 Aug 2008 16:01:48 GMT

Isn't quite a bit of the non-trivial UI done in HTML, via embedded WebBrowser controls? I know the XP Help and Support Center does that.

re: What’s wrong with this code, Part 22 – the answers

Pascal — Tue, 05 Aug 2008 14:29:19 GMT

Hi Larry,

Is there a good reason to initialize rcText this way ?

RECT rcText = {0, 0, 88, 34};

Thanks for this interesting post.

re: What’s wrong with this code, Part 22 – the answers

Larry Osterman [MSFT] — Tue, 05 Aug 2008 09:17:43 GMT

"me": You're wrong. I have no idea where you work, but in my division we absolutely do NOT use WPF. The same is true for almost all of the Windows division.

For various reasons the volume control UI doesn't use one of the internal frameworks (unless you count ATL as an "internal framework").

re: What’s wrong with this code, Part 22 – the answers

me — Tue, 05 Aug 2008 07:55:53 GMT

Technically speaking, if you're writing UI inside of MS, you should not use GDI. WPF would be good, and if that's no option, one of the internal frameworks. Same applies on the outside

re: What’s wrong with this code, Part 22 – the answers

Miral — Tue, 05 Aug 2008 05:56:07 GMT

@TimHollebeek: the "extra state" *is* already split out and passed as a separate parameter. It's the HDC parameter.

(And as for saving old state, you can use SaveDC/RestoreDC for that purpose.)

@Ben: Using GetDC won't necessarily work. That returns a DC compatible with the window and clipped to its bounds, but not necessarily with the control's font / colour scheme selected. (If it's using a custom font, then it'll almost certainly *not* be selected.)

re: What’s wrong with this code, Part 22 – the answers

Billy — Tue, 05 Aug 2008 04:22:47 GMT

Don't forget to test with ClearType on and off as well. ClearType can have subtle effects on your font sizes as well, though they appear to affect GDI+/managed drawing more than straight GDI.