[maemo-developers] [maemo-developers] SDL vertical blank (vbl) sync.

[From: Tapani Pälli]

ext Frantisek Dufka wrote:
> Visti Andresen wrote:
>
>> My "flashingTest" reports that:
>> It got a hardware surface (I should be writing directly to "video
>> memory" accordingly to the SDL docs)
>> And the surface is double buffered.
>>
>> The size of the surface is 800x480 16 bit (R5G6B5)
>> So there should be at least 1536000 bytes of video memory
>>
>> I suppose the kernel display driver is open-source?
>
> Yes, it is. And I _did_ look at it. And somehow I don't think SDL
> hardware surface really means memory in Epson HWA742 controller :-)
> That's why I asked.
>

I think there's no guarantee that you will get "HW surface" from SDL, it
will silently fallback to SW surface if it cannot have HW one.

SDL draws to X, X draws to the framebuffer mapped by kernel which then
updates that data to the lcd controller where screen gets finally
updated. I would recommend to blit things in memory, then push only
needed parts with SDL_UpdateRects trying to avoid fullscreen updates.

> Frantisek
>

// Tapani

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