Discard framebuffer rendering queues when discarding layers

Bug #5581817

Change-Id: If612846ec5f7793710fc4df152791fb32c506551

5 files changed, 34 insertions, 3 deletions

diff --git a/libs/hwui/Android.mk b/libs/hwui/Android.mk
index 9bfc94c..95e0a18 100644
--- a/libs/hwui/Android.mk
+++ b/libs/hwui/Android.mk
@@ -38,7 +38,7 @@ ifeq ($(USE_OPENGL_RENDERER),true)
 		external/skia/src/ports \
 		external/skia/include/utils
 
-	LOCAL_CFLAGS += -DUSE_OPENGL_RENDERER
+	LOCAL_CFLAGS += -DUSE_OPENGL_RENDERER -DGL_GLEXT_PROTOTYPES
 	LOCAL_CFLAGS += -fvisibility=hidden
 	LOCAL_MODULE_CLASS := SHARED_LIBRARIES
 	LOCAL_SHARED_LIBRARIES := libcutils libutils libGLESv2 libskia libui
diff --git a/libs/hwui/Extensions.h b/libs/hwui/Extensions.h
index 38d1130..48e4247 100644
--- a/libs/hwui/Extensions.h
+++ b/libs/hwui/Extensions.h
@@ -66,6 +66,7 @@ public:
 
         mHasNPot = hasExtension("GL_OES_texture_npot");
         mHasFramebufferFetch = hasExtension("GL_NV_shader_framebuffer_fetch");
+        mHasDiscardFramebuffer = hasExtension("GL_EXT_discard_framebuffer");
 
         const char* vendor = (const char*) glGetString(GL_VENDOR);
         EXT_LOGD("Vendor: %s", vendor);
@@ -80,6 +81,7 @@ public:
     inline bool hasNPot() const { return mHasNPot; }
     inline bool hasFramebufferFetch() const { return mHasFramebufferFetch; }
     inline bool needsHighpTexCoords() const { return mNeedsHighpTexCoords; }
+    inline bool hasDiscardFramebuffer() const { return mHasDiscardFramebuffer; }
 
     bool hasExtension(const char* extension) const {
         const String8 s(extension);
@@ -98,6 +100,7 @@ private:
     bool mHasNPot;
     bool mNeedsHighpTexCoords;
     bool mHasFramebufferFetch;
+    bool mHasDiscardFramebuffer;
 }; // class Extensions
 
 }; // namespace uirenderer
diff --git a/libs/hwui/LayerRenderer.cpp b/libs/hwui/LayerRenderer.cpp
index e38b479..b7c079b 100644
--- a/libs/hwui/LayerRenderer.cpp
+++ b/libs/hwui/LayerRenderer.cpp
@@ -305,8 +305,10 @@ void LayerRenderer::destroyLayer(Layer* layer) {
         LAYER_RENDERER_LOGD("Recycling layer, %dx%d fbo = %d",
                 layer->getWidth(), layer->getHeight(), layer->getFbo());
 
-        if (layer->getFbo()) {
-            Caches::getInstance().fboCache.put(layer->getFbo());
+        GLuint fbo = layer->getFbo();
+        if (fbo) {
+            flushLayer(layer);
+            Caches::getInstance().fboCache.put(fbo);
         }
 
         if (!Caches::getInstance().layerCache.put(layer)) {
@@ -331,6 +333,26 @@ void LayerRenderer::destroyLayerDeferred(Layer* layer) {
     }
 }
 
+void LayerRenderer::flushLayer(Layer* layer) {
+#ifdef GL_EXT_discard_framebuffer
+    GLuint fbo = layer->getFbo();
+    if (layer && fbo) {
+        // If possible, discard any enqued operations on deferred
+        // rendering architectures
+        if (Caches::getInstance().extensions.hasDiscardFramebuffer()) {
+            GLuint previousFbo;
+            glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint*) &previousFbo);
+
+            GLenum attachments = GL_COLOR_ATTACHMENT0;
+            glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+            glDiscardFramebufferEXT(GL_FRAMEBUFFER, 1, &attachments);
+
+            glBindFramebuffer(GL_FRAMEBUFFER, previousFbo);
+        }
+    }
+#endif
+}
+
 bool LayerRenderer::copyLayer(Layer* layer, SkBitmap* bitmap) {
     Caches& caches = Caches::getInstance();
     if (layer && layer->isTextureLayer() && bitmap->width() <= caches.maxTextureSize &&
diff --git a/libs/hwui/LayerRenderer.h b/libs/hwui/LayerRenderer.h
index 6104301..72d8d81 100644
--- a/libs/hwui/LayerRenderer.h
+++ b/libs/hwui/LayerRenderer.h
@@ -61,6 +61,7 @@ public:
             bool isOpaque, GLenum renderTarget, float* transform);
     ANDROID_API static void destroyLayer(Layer* layer);
     ANDROID_API static void destroyLayerDeferred(Layer* layer);
+    ANDROID_API static void flushLayer(Layer* layer);
     ANDROID_API static bool copyLayer(Layer* layer, SkBitmap* bitmap);
 
 private:
diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index 32595e4..1a8c199 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -611,6 +611,11 @@ void OpenGLRenderer::composeLayer(sp<Snapshot> current, sp<Snapshot> previous) {
     }
 
     if (fboLayer) {
+        // Note: No need to use glDiscardFramebufferEXT() since we never
+        //       create/compose layers that are not on screen with this
+        //       code path
+        // See LayerRenderer::destroyLayer(Layer*)
+
         // Detach the texture from the FBO
         glBindFramebuffer(GL_FRAMEBUFFER, current->fbo);
         glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0);