haraldwolff/qemu-patch-raspberry4
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sdl: restore optimized redraw

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The documentation on SDL_RenderPresent function states that
"the backbuffer should be considered invalidated after each present",
so copy the entire texture on each redraw.

On the other hand, SDL_UpdateTexture function is described as
"fairly slow function", so restrict it to just the changed pixels.

Also added SDL_RenderClear call, as suggested in the documentation
page on SDL_RenderPresent.

Signed-off-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Message-id: 20180205133228.25082-1-anatoly.trosinenko@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Anatoly Trosinenko 2018-02-05 16:32:28 +03:00 committed by Gerd Hoffmann
parent d49b87f0d1
commit 2ab858c6c3
1 changed files with 6 additions and 15 deletions
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21
ui/sdl2-2d.c
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@ -36,6 +36,8 @@ void sdl2_2d_update(DisplayChangeListener *dcl,
struct sdl2_console *scon = container_of(dcl, struct sdl2_console, dcl);
DisplaySurface *surf = qemu_console_surface(dcl->con);
SDL_Rect rect;
size_t surface_data_offset = surface_bytes_per_pixel(surf) * x +
surface_stride(surf) * y;
assert(!scon->opengl);
@ -46,27 +48,16 @@ void sdl2_2d_update(DisplayChangeListener *dcl,
return;
}
/*
* SDL2 seems to do some double-buffering, and trying to only
* update the changed areas results in only one of the two buffers
* being updated. Which flickers alot. So lets not try to be
* clever do a full update every time ...
*/
#if 0
rect.x = x;
rect.y = y;
rect.w = w;
rect.h = h;
#else
rect.x = 0;
rect.y = 0;
rect.w = surface_width(surf);
rect.h = surface_height(surf);
#endif
SDL_UpdateTexture(scon->texture, NULL, surface_data(surf),
SDL_UpdateTexture(scon->texture, &rect,
surface_data(surf) + surface_data_offset,
surface_stride(surf));
SDL_RenderCopy(scon->real_renderer, scon->texture, &rect, &rect);
SDL_RenderClear(scon->real_renderer);
SDL_RenderCopy(scon->real_renderer, scon->texture, NULL, NULL);
SDL_RenderPresent(scon->real_renderer);
}