Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

Stephane Rodriguez — Sat, 11 Mar 2006 11:49:48 GMT

"Instead, DirectX is able to maintain a "flip chain" of buffers and swap between them for what's displayed on the screen. The "flip" happens at a very low level in the system and does occur during vblank. But it doesn't require drawing."

Thanks for your answer. What you describe here is what we used to do back in the old days : we had a bunch of back buffers and we would blit them back and forth (with the help of marvelous blitter and copper chips on the Amiga for instance). Up until we would reach the actual desktop buffer. Thing is, when drawing on the desktop buffer itself, we wouldn't blip the entire screen from back buffers, but restrict to portions, hence the "let's avoid the drawing spot" craze. The only limiting factor at the time was how many large blits we'd be able to do in a VBL. From what I understand, there is nothing really new, just that the resolution is bigger now and the processing power has dramatically improved. The Atari/Amiga were on the 7MHz CPU range.

re: Responding to Comments from "Under the Hood of the DWM"

Anonymous — Sat, 11 Mar 2006 16:10:03 GMT

Ah, sounds good. I got the impression from another blog post by some other 'softie, can't find it now, that as soon as an Avalon window started using per-pixel transparency, it's internal drawing would no longer be hardware accelerated at all.

Desktop Window Manager — подробности, подробности и ещё раз подробности!

Олег Михайлик — Sun, 12 Mar 2006 00:15:48 GMT

Грег Сшечтер отвечает на вопросы по своей краеугольной статье о DWM. Пожалуй, да

Peaceful Coexistence - Windows Vista's Desktop Experience and Applications

Pablo Fernicola's Personal Blog — Sun, 12 Mar 2006 01:31:10 GMT

I read and participate in newsgroups (and blogs) regularly. This entry is derived from a recent long post of mine in response to some very passionate newsgroup posts by some folks using the latest Windows Vista CTP

The are a number of very positive

re: Responding to Comments from "Under the Hood of the DWM"

deebs — Sun, 12 Mar 2006 21:58:10 GMT

I can accept the Amiga/Atari similarities and those are fine.

However, whatever the software/hardware approach may be the finesse, in my opinion, is in the construction. These are neat with a very fine construction and effective use of z-stacking effects.

great converastion going on Greg's blog

Kam VedBrat — Mon, 13 Mar 2006 10:17:06 GMT

Greg's started a great converation on his blog about the internals of the DWM.
I want to take a second...

re: Responding to Comments from "Under the Hood of the DWM"

CodeMonkey — Tue, 14 Mar 2006 04:54:53 GMT

This has been a great blog entry Greg. I have a couple of questions that I would love to see answered.

1. Do you know of a solution to the mirror driver vs. compositing engine problem? To recap it, the mirror driver has been an excellent method of getting screen contents in an efficient manner, however, in Vista a mirror driver will force the compositing engine to turn off. Has there been a method identified to get the composited screen contents back from the video hardware in an efficient way?

2. Is there an API to get the contents of windows belonging to a specific application (either before or after the composition engine takes it for its magic carpet ride)? Furthermore is there a way to get those contents AND the surrounding window frame?

Thanks Greg. I'm looking forward to more great info on DWM and the reworked Graphics/Video pipeline.

re: Responding to Comments from "Under the Hood of the DWM"

Oluf Nissen — Thu, 16 Mar 2006 07:44:24 GMT

Greg,

I really liked your talk at the PDC (a late compliment, I know!) That 15 puzzle demo just blew me away. Anyway, here's my real comment:

I noticed that the DWM sometimes gets turned off, so that the "Glass" experience is disabled. Under what circumstances does this happen? How does Vista detect that the DWM needs to be turned off?

I noticed this happening when running iTunes 6.0.2.23 and QuickTime Player 7.0.4.

Any comments?

re: Responding to Comments from "Under the Hood of the DWM"

Michael Price — Thu, 16 Mar 2006 16:32:57 GMT

Oluf,

I noticed the iTunes/QuickTime badness recently as well. I'm not sure, but my uninformed guess is that Apple is using DirectDraw to draw their iTunes window. Use of DirectDraw will disable desktop composition. I also assume that Apple is planning on fixing this.

I'm sure Greg can elaborate on the conditions that turn off the composition engine. At least the OS autodetects when it is safe to reenable.

Michael Price

re: Responding to Comments from "Under the Hood of the DWM"

PatriotB — Mon, 20 Mar 2006 00:58:12 GMT

"2. Is there an API to get the contents of windows belonging to a specific application (either before or after the composition engine takes it for its magic carpet ride)?"

PrintWindow(), WM_PRINT and/or WM_PRINTCLIENT may be what you're looking for. Not sure whether they can include the DWM-rendered window frame.

re: Responding to Comments from "Under the Hood of the DWM"

Arlie Davis — Wed, 05 Apr 2006 21:04:58 GMT

Stephane,

What occurs is actually a lot faster than blitting a back buffer to the front buffer during vblank. All modern graphics cards simply use a pointer to the current front buffer, so "flipping" is as easy as changing a register in the graphics card. Then the hardware that reads pixel values and sends them to the DACs (for analog RGB) or to the digital DVI just reads pixels from a different memory location.

re: Responding to Comments from "Under the Hood of the DWM"

Wed, 05 Apr 2006 23:17:40 GMT

> I assume you're referring to the issue on XP
> and before that when you drag a window with
> video, the video lags the window. That's
> because in those systems, hardware overlays are
> being used. In Vista, the window is
> composited, and everything is in sync, so no
> more lag.

I hope overlays are still an option. Every other method to playback videos increases CPU usage brutally - up to the point where most CPU is spent on that. I can do 1280x720 with overlays, but only 640x480 without, even using hardware colorspace conversion and resizing. For example VMR9 is "bad" - very bad for me. I don't care about the glitches - I know where they come from, no problem.

Desktop Window Manager Index of Post Topics

Greg Schechter's Blog — Fri, 21 Apr 2006 10:06:00 GMT

Here's a list of topics that I have posted on (with active links) or expect to post on (without links)...

DWM & Aero Glass at work

David Boschmans Weblog — Thu, 08 Jun 2006 14:01:36 GMT

When talking about WPF during the Windows Vista ISV Touchdown training a lot of people were interested...

DWM & Aero Glass at work

David Boschmans Weblog — Thu, 31 May 2007 16:58:21 GMT

When talking about WPF during the Windows Vista ISV Touchdown training a lot of people were interested

There is no .NET in Vista Code? - Page 2 | keyongtech

There is no .NET in Vista Code? - Page 2 | keyongtech — Thu, 22 Jan 2009 11:05:27 GMT

PingBack from http://www.keyongtech.com/4483729-there-is-no-net-in/2

Greg Schechter s Blog Responding to Comments from Under the Hood of | Wood TV Stand

Mon, 01 Jun 2009 03:32:32 GMT

PingBack from http://woodtvstand.info/story.php?id=6527

Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

Desktop Window Manager — подробности, подробности и ещё раз подробности!

Peaceful Coexistence - Windows Vista's Desktop Experience and Applications

re: Responding to Comments from "Under the Hood of the DWM"

great converastion going on Greg's blog

re: Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

re: Responding to Comments from "Under the Hood of the DWM"

Desktop Window Manager Index of Post Topics

DWM &amp; Aero Glass at work

DWM & Aero Glass at work

There is no .NET in Vista Code? - Page 2 | keyongtech

Greg Schechter s Blog Responding to Comments from Under the Hood of | Wood TV Stand

DWM & Aero Glass at work