Fuchsia: convert framebuffer pixel format after drawing if needed (#3031)

content_handler/framebuffer_skia.cc

@@ -88,4 +88,25 @@ void FramebufferSkia::Bind(mojo::InterfaceHandle<mojo::Framebuffer> framebuffer,
       backing_store_info);
 }
 
+void FramebufferSkia::ConvertToCorrectPixelFormatIfNeeded() {
+  if (info_->format == mojo::FramebufferFormat::ARGB_8888) {
+    // we need to convert from RGBA to ARGB
+    SkPixmap bufferPixmap;
+
+    if (surface_->peekPixels(&bufferPixmap)) {
+      uint8_t* buffer = reinterpret_cast<uint8_t*>(bufferPixmap.writable_addr());
+      size_t buffer_size = bufferPixmap.getSafeSize();
+      uint8_t src_r;
+      for (size_t i = 0; i < buffer_size; i++) {
+        src_r = buffer[0];
+        buffer[0] /* A */ = buffer[3];
+        buffer[3] /* B */ = buffer[2];
+        buffer[2] /* G */ = buffer[1];
+        buffer[1] /* R */ = src_r;
+        i +=4;
+      }
+    }
+  }
+}
+
 }  // namespace flutter_content_handler

content_handler/framebuffer_skia.h

@@ -19,6 +19,10 @@ class FramebufferSkia {
   void Bind(mojo::InterfaceHandle<mojo::Framebuffer> framebuffer,
             mojo::FramebufferInfoPtr info);
 
+  // Converts pixels from internal format of BGRA to ARGB.
+  // Needed because Skia does not support drawing to ARGB directly.
+  void ConvertToCorrectPixelFormatIfNeeded();
+
   mojo::Framebuffer* get() const { return framebuffer_.get(); }
   const sk_sp<SkSurface>& surface() { return surface_; }
 

content_handler/rasterizer.cc

@@ -35,6 +35,8 @@ void Rasterizer::Draw(std::unique_ptr<flow::LayerTree> layer_tree,
   layer_tree->Raster(frame);
   canvas->flush();
 
+  framebuffer_.ConvertToCorrectPixelFormatIfNeeded();
+
   framebuffer_.get()->Flush(ftl::MakeRunnable(std::move(callback)));
 }