Ping. Patchwork link: http://patchwork.ozlabs.org/patch/869283/
2018-02-05 16:32 GMT+03:00 Anatoly Trosinenko <anatoly.trosine...@gmail.com> : > 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.trosine...@gmail.com> > --- > I managed to reproduce some flicker when using SDL 2D UI (and #if 1) > and it disappeared after this patch. I don't know the original > testcase, though. Hope I correctly calculated the offset. :) > > Meanwhile, is it correct to calculate surface_data_offset before assert, > is everything always initialized enough at this point even if assert fails? > > ui/sdl2-2d.c | 23 +++++++---------------- > 1 file changed, 7 insertions(+), 16 deletions(-) > > diff --git a/ui/sdl2-2d.c b/ui/sdl2-2d.c > index 8ab68d67b9..1f34817bae 100644 > --- a/ui/sdl2-2d.c > +++ b/ui/sdl2-2d.c > @@ -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); > } > > -- > 2.14.1 > > -- С уважением, Анатолий Тросиненко e-mail: anatoly.trosine...@gmail.com
