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gems/gui_buffer.h: atomic back-to-front blitting
This patch updates menu_view, themed_decorator, and rom_osci to use the new frame-buffer blit operation, mitigating tearing artifacts Issue #5350
This commit is contained in:
Norman Feske
Christian Helmuth
parent
4565cd0143
commit
6522158caa
@ -36,6 +36,7 @@ struct Gui_buffer : Genode::Noncopyable
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using Point = Genode::Surface_base::Point;
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using Ram_ds = Genode::Attached_ram_dataspace;
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using size_t = Genode::size_t;
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using uint8_t = Genode::uint8_t;
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Genode::Ram_allocator &ram;
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Genode::Region_map &rm;
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@ -53,31 +54,59 @@ struct Gui_buffer : Genode::Noncopyable
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*/
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Genode::Dataspace_capability _ds_cap(Gui::Connection &gui)
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{
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/* setup virtual framebuffer mode */
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gui.buffer(mode, use_alpha);
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/*
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* Setup virtual framebuffer, the upper part containing the front
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* buffer, the lower part containing the back buffer.
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*/
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gui.buffer({ .area = { mode.area.w, mode.area.h*2 } }, use_alpha);
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return gui.framebuffer.dataspace();
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}
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Genode::Attached_dataspace fb_ds { rm, _ds_cap(gui) };
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Genode::Attached_dataspace _fb_ds { rm, _ds_cap(gui) };
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size_t pixel_surface_num_bytes() const
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size_t _pixel_num_bytes() const { return size().count()*sizeof(Pixel_rgb888); }
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size_t _alpha_num_bytes() const { return use_alpha ? size().count() : 0; }
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size_t _input_num_bytes() const { return use_alpha ? size().count() : 0; }
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void _with_pixel_ptr(auto const &fn)
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{
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return size().count()*sizeof(Pixel_rgb888);
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/* skip pixel front buffer */
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uint8_t * const ptr = _fb_ds.local_addr<uint8_t>() + _pixel_num_bytes();
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fn((Pixel_rgb888 *)ptr);
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}
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size_t alpha_surface_num_bytes() const
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void _with_alpha_ptr(auto const &fn)
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{
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return use_alpha ? size().count() : 0;
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if (!use_alpha)
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return;
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/* skip pixel front buffer, pixel back buffer, and alpha front buffer */
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uint8_t * const ptr = _fb_ds.local_addr<uint8_t>()
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+ _pixel_num_bytes()*2 + _alpha_num_bytes();
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fn((Pixel_alpha8 *)ptr);
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}
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Ram_ds pixel_surface_ds { ram, rm, pixel_surface_num_bytes() };
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Ram_ds alpha_surface_ds { ram, rm, alpha_surface_num_bytes() };
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void _with_input_ptr(auto const &fn)
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{
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if (!use_alpha)
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return;
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/* skip pixel buffers, alpha buffers, and input front buffer */
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uint8_t * const ptr = _fb_ds.local_addr<uint8_t>()
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+ _pixel_num_bytes()*2 + _alpha_num_bytes()*2 + _input_num_bytes();
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fn(ptr);
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}
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enum class Alpha { OPAQUE, ALPHA };
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static Genode::Color default_reset_color()
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{
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/*
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* Do not use black by default to limit the bleeding of black into
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* antialiased drawing operations applied onto an initially transparent
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* background.
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*/
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return Genode::Color(127, 127, 127, 255);
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}
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@ -99,27 +128,25 @@ struct Gui_buffer : Genode::Noncopyable
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}
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/**
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* Return size of virtual framebuffer
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* Return size of the drawing surface
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*/
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Area size() const { return mode.area; }
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template <typename FN>
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void with_alpha_surface(FN const &fn)
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void with_alpha_surface(auto const &fn)
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{
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Area const alpha_size = use_alpha ? size() : Area(0, 0);
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Alpha_surface alpha(alpha_surface_ds.local_addr<Pixel_alpha8>(), alpha_size);
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fn(alpha);
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_with_alpha_ptr([&] (Pixel_alpha8 *ptr) {
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Alpha_surface alpha { ptr, size() };
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fn(alpha); });
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}
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template <typename FN>
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void with_pixel_surface(FN const &fn)
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void with_pixel_surface(auto const &fn)
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{
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Pixel_surface pixel(pixel_surface_ds.local_addr<Pixel_rgb888>(), size());
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fn(pixel);
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_with_pixel_ptr([&] (Pixel_rgb888 *ptr) {
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Pixel_surface pixel { ptr, size() };
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fn(pixel); });
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}
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template <typename FN>
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void apply_to_surface(FN const &fn)
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void apply_to_surface(auto const &fn)
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{
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with_alpha_surface([&] (Alpha_surface &alpha) {
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with_pixel_surface([&] (Pixel_surface &pixel) {
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@ -128,18 +155,11 @@ struct Gui_buffer : Genode::Noncopyable
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void reset_surface()
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{
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if (use_alpha)
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with_alpha_surface([&] (Alpha_surface &alpha) {
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Genode::memset(alpha.addr(), 0, alpha_surface_num_bytes()); });
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with_alpha_surface([&] (Alpha_surface &alpha) {
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Genode::memset(alpha.addr(), 0, _alpha_num_bytes()); });
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with_pixel_surface([&] (Pixel_surface &pixel) {
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/*
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* Initialize color buffer with 50% gray
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*
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* We do not use black to limit the bleeding of black into antialiased
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* drawing operations applied onto an initially transparent background.
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*/
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Pixel_rgb888 *dst = pixel.addr();
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Pixel_rgb888 const color = reset_color;
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@ -148,71 +168,32 @@ struct Gui_buffer : Genode::Noncopyable
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});
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}
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template <typename DST_PT, typename SRC_PT>
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void _convert_back_to_front(DST_PT *front_base,
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Genode::Texture<SRC_PT> const &texture,
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Rect const clip_rect)
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{
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Genode::Surface<DST_PT> surface(front_base, size());
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surface.clip(clip_rect);
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Blit_painter::paint(surface, texture, Point());
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}
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void _update_input_mask()
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{
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if (!use_alpha)
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return;
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_with_alpha_ptr([&] (Pixel_alpha8 const * const alpha_ptr) {
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_with_input_ptr([&] (uint8_t *dst) {
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size_t const num_pixels = size().count();
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/*
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* Set input mask for all pixels where the alpha value is above
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* a given threshold. The threshold is defined such that
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* typical drop shadows are below the value.
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*/
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uint8_t const threshold = 100;
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uint8_t const * src = (uint8_t const *)alpha_ptr;
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size_t const num_pixels = size().count();
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unsigned char * const alpha_base = fb_ds.local_addr<unsigned char>()
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+ mode.bytes_per_pixel()*num_pixels;
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unsigned char * const input_base = alpha_base + num_pixels;
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unsigned char const *src = alpha_base;
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unsigned char *dst = input_base;
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/*
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* Set input mask for all pixels where the alpha value is above a
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* given threshold. The threshold is defined such that typical
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* drop shadows are below the value.
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*/
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unsigned char const threshold = 100;
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for (unsigned i = 0; i < num_pixels; i++)
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*dst++ = (*src++) > threshold;
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for (unsigned i = 0; i < num_pixels; i++)
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*dst++ = (*src++) > threshold;
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});
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});
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}
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void flush_surface()
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{
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// XXX track dirty rectangles
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Rect const clip_rect(Genode::Surface_base::Point(0, 0), size());
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_update_input_mask();
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{
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/* represent back buffer as texture */
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Genode::Texture<Pixel_rgb888>
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pixel_texture(pixel_surface_ds.local_addr<Pixel_rgb888>(),
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nullptr, size());
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Pixel_rgb888 *pixel_base = fb_ds.local_addr<Pixel_rgb888>();
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_convert_back_to_front(pixel_base, pixel_texture, clip_rect);
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}
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if (use_alpha) {
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Genode::Texture<Pixel_alpha8>
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alpha_texture(alpha_surface_ds.local_addr<Pixel_alpha8>(),
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nullptr, size());
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Pixel_alpha8 *alpha_base = fb_ds.local_addr<Pixel_alpha8>()
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+ mode.bytes_per_pixel()*size().count();
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_convert_back_to_front(alpha_base, alpha_texture, clip_rect);
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_update_input_mask();
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}
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/* copy lower part of virtual framebuffer to upper part */
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gui.framebuffer.blit({ { 0, int(size().h) }, size() }, { 0, 0 });
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}
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};
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