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Intermediate. Assumes working knowledge.
22K views17 years ago1 recommendation
Systems programmingGraphics and audioOperating systemsPerformance and optimizationRendering
A demonstration of the 2D rendering performance differences between Windows XP and Windows 7 due to changes in GDI hardware acceleration.
This video demonstrates the slowness of the new Windows 7 GUI. Windows Display Drivers Model used in both Vista and 7 doesn't include the neccesary hardware accelerated 2D functions to make the graphics generated by GDI and GDI+ as fast as in Windows XP. Microsoft chose software render because they found too difficult to combine the new graphical engine with the old one. If you want to learn more about it read this: blogs.msdn.com/directx/archive/2009/05/12/2d-drawing-apis-in… GDI has dozens of functions: msdn.microsoft.com/en-us/library/dd145203%28VS.85%29.aspx GDI hardware acceleration in Windows 7 using WDDM 1.1 drivers has only these functions hardware accelerated: msdn.microsoft.com/en-us/library/dd434692.aspx WDDM 1.1 drivers makes mandatory this new "partial" GDI hardware acceleration. So any driver which claims to be 1.1 is already accelerating as much as it ever will. Too bad, the results I got were based on WDDM 1.1 drivers (both from nvidia and Microsoft itself). The video shows how slow is the services.msc window, and the graphical artifacts it has, but it's not the only one. The file explorer scrolling is also much slower than in XP. ( youtube.com/watch?v=ToFgYylqP_U ) The example in the video is probably one of the applications where this problem is more easily spotted but there are many others which show the same behavior in a different degrees depending on how they call GDI functions. Windows 7 has several integrated solutions to circumvent the lack of 2d graphical acceleration...the problem is those solutions require full rewrite of the every single application's gui in order to use the new direct2d and directwrite, including the ones bundled with the os (file explorer, dialog boxes, management windows, etc...) and that's not going to happen in years, not from Microsoft itself, nor from 3rd party developers. I don't see Adobe porting their suite to Direct2D any soon..and anyway, the system will always stay GDI/GDI+ based. I think they probably won't start gui rewriting until the next major Windows version is released.. Meanwhile we will not see any better results in this area over the time other than the ones related with the improvement in cpu speeds. So this is all we get. Microsoft had to include this partial GDI acceleration, because those functions were way too slow in software mode, but it seems they thought the rest of them were not.....(which is not correct). About the real world impact. I can clearly see the real world impact of this decision as soon as I boot Windows 7 and start working, but there is people who's not able to see the difference between a game running at 60 fps from the same game running a 30 fps or earing the difference between a 128kb mp3 and a real CD Audio. I guess all depends on how fast you are used to work with your computer, and wether Vista already seemed slow or not for you. All I can say is, there is a real diffWhat people say. Engineers point to this video to demonstrate how Windows UI responsiveness declined after Windows XP due to changes in the driver model.
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