Remove the startup flash on Android (#3036)

We need to block in the surfaceChanged callback until we can swap the GL
surface with some content in order to avoid flashing transparent and then
black.

Fixes https://github.com/flutter/flutter/issues/5373

sky/shell/gpu/direct/rasterizer_direct.cc

@@ -48,7 +48,7 @@ void RasterizerDirect::Setup(
     PlatformView* platform_view,
     ftl::Closure continuation,
     ftl::AutoResetWaitableEvent* setup_completion_event) {
-  CHECK(platform_view) << "Must be able to acquire the view.";
+  FTL_CHECK(platform_view) << "Must be able to acquire the view.";
 
   // The context needs to be made current before the GrGL interface can be
   // setup.
@@ -56,15 +56,16 @@ void RasterizerDirect::Setup(
   if (success) {
     success = ganesh_canvas_.SetupGrGLInterface();
     if (!success)
-      LOG(ERROR) << "Could not create the GL interface";
+      FTL_LOG(ERROR) << "Could not create the GL interface";
   } else {
-    LOG(ERROR) << "Could not make the context current for initial GL setup";
+    FTL_LOG(ERROR) << "Could not make the context current for initial GL setup";
   }
 
   if (success) {
     platform_view_ = platform_view;
   } else {
-    LOG(ERROR) << "WARNING: Flutter will be unable to render to the display";
+    FTL_LOG(ERROR)
+        << "WARNING: Flutter will be unable to render to the display";
   }
 
   continuation();
@@ -72,6 +73,14 @@ void RasterizerDirect::Setup(
   setup_completion_event->Signal();
 }
 
+void RasterizerDirect::Clear(SkColor color) {
+  SkCanvas* canvas = ganesh_canvas_.GetCanvas(
+      platform_view_->DefaultFramebuffer(), platform_view_->GetSize());
+  canvas->clear(color);
+  canvas->flush();
+  platform_view_->SwapBuffers();
+}
+
 // sky::shell::Rasterizer override.
 void RasterizerDirect::Teardown(
     ftl::AutoResetWaitableEvent* teardown_completion_event) {
@@ -90,9 +99,8 @@ void RasterizerDirect::Draw(
     ftl::RefPtr<flutter::Pipeline<flow::LayerTree>> pipeline) {
   TRACE_EVENT0("flutter", "RasterizerDirect::Draw");
 
-  if (platform_view_ == nullptr) {
+  if (!platform_view_)
     return;
-  }
 
   flutter::Pipeline<flow::LayerTree>::Consumer consumer =
       std::bind(&RasterizerDirect::DoDraw, this, std::placeholders::_1);
@@ -107,14 +115,15 @@ void RasterizerDirect::Draw(
           weak_this->Draw(pipeline);
         }
       });
-    } break;
+      break;
+    }
     default:
       break;
   }
 }
 
 void RasterizerDirect::DoDraw(std::unique_ptr<flow::LayerTree> layer_tree) {
-  if (layer_tree == nullptr) {
+  if (!layer_tree) {
     return;
   }
 

sky/shell/gpu/direct/rasterizer_direct.h

@@ -20,22 +20,19 @@ class RasterizerDirect : public Rasterizer {
 
   ~RasterizerDirect() override;
 
-  // sky::shell::Rasterizer override.
   void Setup(PlatformView* platform_view,
              ftl::Closure continuation,
              ftl::AutoResetWaitableEvent* setup_completion_event) override;
 
-  // sky::shell::Rasterizer override.
+  void Clear(SkColor color) override;
+
   void Teardown(
       ftl::AutoResetWaitableEvent* teardown_completion_event) override;
 
-  // sky::shell::Rasterizer override.
   ftl::WeakPtr<sky::shell::Rasterizer> GetWeakRasterizerPtr() override;
 
-  // sky::shell::Rasterizer override.
   flow::LayerTree* GetLastLayerTree() override;
 
-  // sky::shell::Rasterizer override.
   void Draw(ftl::RefPtr<flutter::Pipeline<flow::LayerTree>> pipeline) override;
 
  private:

sky/shell/platform/android/io/flutter/view/FlutterView.java

@@ -17,6 +17,7 @@ import android.graphics.Rect;
 import android.os.Build;
 import android.util.AttributeSet;
 import android.util.Log;
+import android.util.TypedValue;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 import android.view.Surface;
@@ -115,15 +116,25 @@ public class FlutterView extends SurfaceView
         attach();
         assert mNativePlatformView != 0;
 
+        int color = 0xFF000000;
+        TypedValue typedValue = new TypedValue();
+        context.getTheme().resolveAttribute(android.R.attr.colorBackground, typedValue, true);
+        if (typedValue.type >= TypedValue.TYPE_FIRST_COLOR_INT && typedValue.type <= TypedValue.TYPE_LAST_COLOR_INT)
+          color = typedValue.data;
+        // TODO(abarth): Consider letting the developer override this color.
+        final int backgroundColor = color;
+
         mSurfaceCallback = new SurfaceHolder.Callback() {
             @Override
-            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
+            public void surfaceCreated(SurfaceHolder holder) {
+                assert mNativePlatformView != 0;
+                nativeSurfaceCreated(mNativePlatformView, holder.getSurface());
             }
 
             @Override
-            public void surfaceCreated(SurfaceHolder holder) {
+            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                 assert mNativePlatformView != 0;
-                nativeSurfaceCreated(mNativePlatformView, holder.getSurface());
+                nativeSurfaceChanged(mNativePlatformView, backgroundColor);
             }
 
             @Override
@@ -513,6 +524,7 @@ public class FlutterView extends SurfaceView
     private static native void nativeDetach(long nativePlatformViewAndroid);
     private static native void nativeSurfaceCreated(long nativePlatformViewAndroid,
                                                     Surface surface);
+    private static native void nativeSurfaceChanged(long nativePlatformViewAndroid, int backgroundColor);
     private static native void nativeSurfaceDestroyed(long nativePlatformViewAndroid);
     private static native Bitmap nativeGetBitmap(long nativePlatformViewAndroid);
 

sky/shell/platform/android/platform_view_android.cc

@@ -400,11 +400,14 @@ void PlatformViewAndroid::SurfaceCreated(JNIEnv* env,
     }
     ANativeWindow_release(window);
   }
+}
 
-  NotifyCreated();
-
+void PlatformViewAndroid::SurfaceChanged(JNIEnv* env,
+                                         jobject obj,
+                                         jint backgroundColor) {
+  NotifyCreated(
+      [this, backgroundColor] { config_.rasterizer->Clear(backgroundColor); });
   SetupResourceContextOnIOThread();
-
   UpdateThreadPriorities();
 }
 

sky/shell/platform/android/platform_view_android.h

@@ -30,6 +30,9 @@ class PlatformViewAndroid : public PlatformView {
   // Called from Java
   void SurfaceCreated(JNIEnv* env, jobject obj, jobject jsurface);
 
+  // Called from Java
+  void SurfaceChanged(JNIEnv* env, jobject obj, jint backgroundColor);
+
   // Called from Java
   void SurfaceDestroyed(JNIEnv* env, jobject obj);
 

sky/shell/platform_view.cc

@@ -56,23 +56,17 @@ void PlatformView::NotifyCreated() {
 }
 
 void PlatformView::NotifyCreated(ftl::Closure rasterizer_continuation) {
-  CHECK(config_.rasterizer != nullptr);
-
-  auto rasterizer = config_.rasterizer->GetWeakRasterizerPtr();
+  FTL_CHECK(config_.rasterizer);
 
   ftl::AutoResetWaitableEvent latch;
-  auto delegate_continuation = [rasterizer, this, rasterizer_continuation,
-                                &latch]() {
-    if (rasterizer)
-      rasterizer->Setup(this, rasterizer_continuation, &latch);
-    // TODO(abarth): We should signal the latch if the rasterizer is gone.
+
+  auto delegate_continuation = [this, rasterizer_continuation, &latch]() {
+    config_.rasterizer->Setup(this, rasterizer_continuation, &latch);
   };
 
   auto delegate = config_.ui_delegate;
   blink::Threads::UI()->PostTask([delegate, delegate_continuation]() {
-    if (delegate)
-      delegate->OnOutputSurfaceCreated(delegate_continuation);
-    // TODO(abarth): We should signal the latch if the delegate is gone.
+    delegate->OnOutputSurfaceCreated(delegate_continuation);
   });
 
   latch.Wait();

sky/shell/rasterizer.h

@@ -27,6 +27,8 @@ class Rasterizer {
                      ftl::Closure rasterizer_continuation,
                      ftl::AutoResetWaitableEvent* setup_completion_event) = 0;
 
+  virtual void Clear(SkColor color) = 0;
+
   virtual void Teardown(
       ftl::AutoResetWaitableEvent* teardown_completion_event) = 0;