APIs in the Desktop Window Manager

re: APIs in the Desktop Window Manager

Mike — Thu, 14 Sep 2006 17:05:03 GMT

"This is useful for, for instance, the TaskBar or the SideBar which go opaque when other windows get maximized."

Please please PLEASE tell me there's a way to turn that off, it's horribly annoying and distracting and inconsistent, not to mention ugly. Same with the window border/title...

Otherwise, thanks for the info. You mention that Flip3d cannot be built with the Thumbnail API... how could, in fact, something like that be built?

re: APIs in the Desktop Window Manager

guy — Thu, 14 Sep 2006 17:18:38 GMT

Are there any APIs available to actually manipulate/size/move the compositor windows. ie. to let a third party build Expose or Spaces functionality, or something better?

re: APIs in the Desktop Window Manager

jad — Thu, 14 Sep 2006 19:29:48 GMT

I noticed that the WPF screen update rate is pretty low under DWM in Vista RC1. It's not at fast as for example dragging windows on the desktop. Can I change this rate in a WPF application?

re: APIs in the Desktop Window Manager

GreenReaper — Fri, 15 Sep 2006 02:01:43 GMT

Mike: One way is to be the DWM . . . or make it think that you are, anyway. It would be a lot of trouble to go that way, though, and would require that you have a near-complete understanding of how to use the undocumented milcore and WindowsCodecs APIs, and of the final low-level compiled structure of the DWM. It's also very likely to break on you when any of the above components change, even in a trivial way. Not recommended unless you have a year on your hands and yearn for the good old days of low-level GDI calls. Even if you do, think twice. :-)

Another more practical way to do something similar might be to use a fullscreen window and the PrintWindow API to grab the appropriate images, then mess around with them as you like. Unfortunately if you do that they will not update automatically. This loses some coolness, but most users are unlikely to notice.

My advice? Probably best to wait for an 3D Thumbnail API (at which point MS will probably be sued by Apple for allowing people to make Expose or Spaces).

guy: Don't think so. Again, you're talking stuff which only the DWM knows.

jad: I'm not sure what you mean by WPF screen update rate (WPF is the application framework), but it sounds like your graphics subsystem is low on bandwidth. Integrated graphics solutions and older cards are marginal for the purposes of the DWM and will cause the whole screen's frame rate to drop.

I believe WPF itself can specify an rate to milcore, but it doesn't really matter if the whole screen can't handle updating any faster. You can see how much bandwidth you're playing with by looking at MbVideoMemPerSecond in a recent assessment in %WINDIR%\Performance\WinSAT\DataStore. Microsoft recommends 1600 or more for good performance.

re: APIs in the Desktop Window Manager

jad — Fri, 15 Sep 2006 08:23:45 GMT

GreenReaper:

It's not a hardware related problem. WPF applications running under DWM update the screen at a lower rate than the DWM updates other stuff. This happens on high end hardware so obviously WPF apps are set to update at a lower rate. I want to know if I can change this setting as a developer.

You can see the effect easily when you use scroll bars. They lag behind the mouse cursor a little. If DWM is disabled they move as fast as the scroll bars in non-WPF applications. It doesn't look so bad actually, but I'd still like to be able to change this.

re: APIs in the Desktop Window Manager

Brandn Paddock — Sun, 17 Sep 2006 12:18:14 GMT

Theoretically... couldn't an Expose-like application be written using the thumbnail API? (so long as you aren't doing any 3D rotation stuff like Flip 3D)

re: APIs in the Desktop Window Manager

Mike Dunn — Mon, 18 Sep 2006 00:19:56 GMT

I can't remember where I saw it (somewhere in an MS blog, to narrow it down a bit ;) ) but I remember seeing a blog post within the past couple of days from a guy who had written an Exposé-like app and was gonna post it on CodePlex.

re: APIs in the Desktop Window Manager

Simon on the (dot) Net — Mon, 18 Sep 2006 10:13:46 GMT

Mike : The thing you saw was probably this :
http://blogs.labo-dotnet.com/simon/archive/2006/09/12/11116.aspx.
That is in french (yes, I am, sorry ^^), and there is no error / exception handling at all.
The trigger-key is F12 (not configurable in this early version).

This code is using exclusively Dwm thumbnails (via calls to DwmUpdateThumbnailProperties) and is not really performant... That is a shame that in a Vista / Framework .Net 3.0 environment, there is no way to obtain a VisualBrush from these thumbnails.

re: APIs in the Desktop Window Manager

NyaRuRu — Thu, 21 Sep 2006 19:15:13 GMT

Hi Greg,

I have a question about declerations of DwmSetDxFrameDuration and DwmModifyPreviousDxFrameDuration in dwmapi.h

They recieve cRefreshes as Int32.
Should I pass the DXRefreshes to these APIs?
If so, please update the declerations like this.

// cRefreshes -> cDXRefreshes

DWMAPI
DwmSetDxFrameDuration(
HWND hwnd,
INT cDXRefreshes
);

DWMAPI
DwmModifyPreviousDxFrameDuration(
HWND hwnd,
INT cDXRefreshes
BOOL fRelative
);

Glass nugget

Daniel Moth — Fri, 22 Sep 2006 18:27:08 GMT

Glass nugget

A Couple of Cool Uses of the DWM Thumbnail APIs

Greg Schechter's Blog — Thu, 28 Sep 2006 09:44:09 GMT

I've seen a couple of cool uses in the past week of the DWM Thumbnail API (described in my previous post)...

re: APIs in the Desktop Window Manager

Christopher — Mon, 09 Oct 2006 15:28:11 GMT

Making Thumbnails that are larger than the original window seems like it might be useful for an updated version of the Magnafier accessibility tool assuming it can be cropped.

Well, I guess it would also require being able to thumbnail the entire screen rather than just one window at a time, but if it can do that (I don't know but not according to my understanding) then it would be perfect.

Application Thumbnails in Vista

Infosys | Microsoft — Thu, 30 Nov 2006 09:53:21 GMT

Using Application Thumbnails in Vista

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