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From: | Anthony Liguori |
Subject: | Re: [Qemu-devel] [PATCH 4 of 5] sdl shared buffer support |
Date: | Mon, 08 Sep 2008 09:31:11 -0500 |
User-agent: | Thunderbird 2.0.0.16 (X11/20080723) |
Stefano Stabellini wrote:
Anthony Liguori wrote:Stefano Stabellini wrote:This patch implements shared buffer support in sdl.c. It also supports paletted 8 bit colour depths using the palette functions provided by the SDL library.So the theory goes that it's possible with this patch that both surfaces are hardware surfaces so blitting is fast?The theory goes that SDL blitting and color conversion functions should be as optimized as you can get, and hardware accelerated if your card supports it. Besides I think that offloading blitting and color conversion to a graphic library is a good idea.
It requires two paths in the code to handle the case where the backend can't handle conversion itself. If we're not getting any sort of benefit from offloading, then I don't see the need for increased code complexity.
In practice, when using X11 both surfaces are going to be XShmImages so I don't think this is going to perform any better than the current code.Only the guest framebuffer derived surface is always a software surface, the host window can be an hardware surface (as far as I know).
Not when using SDL on X11. It will use an XShmImage if possible, otherwise falling back to a normal XImage. There's really no other way to do surfaces in X11 without using one of the extensions (like DGA).
Regards, Anthony Liguori
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