Implement Raster Backend on Android Viewer App

tools/viewer/sk_app/RasterWindowContext.h

+
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#ifndef RasterWindowContext_DEFINED
+#define RasterWindowContext_DEFINED
+
+#include <android/native_window_jni.h>
+
+#include "SkImage.h"
+#include "WindowContext.h"
+
+namespace sk_app {
+
+class RasterWindowContext : public WindowContext {
+public:
+    sk_sp<SkSurface> getBackbufferSurface() override;
+
+    bool isValid() override { return true; }
+
+    void resize(uint32_t w, uint32_t h) override {

[djsollen, 2016/06/07 16:05:29]

why doesn't the android subclass override this and call
ANativeWindow_setBuffersGeometry

[liyuqian, 2016/06/07 19:19:57]

I'm deleting RasterWindowContext since there isn't much common code in the
RasterWindowContext that can be applied to each platform.

Previously, I did not override this in Android because we never call resize in
Android.

+        // Override this in the subclass to allow resize
+        SkDEBUGFAIL("Resize is currently unsupported.");
+    }
+
+    void swapBuffers() override;
+
+    void setDisplayParams(const DisplayParams& params) override {
+        // Override this in the subclass to allow setDisplayParams in runtime
+        SkDEBUGFAIL("setDisplayParams is currently unsupported.");

[djsollen, 2016/06/07 16:05:29]

why doesn't the android subclass override this?

[liyuqian, 2016/06/07 19:19:57]

I'm deleting RasterWindowContext since there isn't much common code in the
RasterWindowContext that can be applied to each platform.

Previously, I did not override this in Android because we never call
setDisplayParams in
Android.

+    }
+
+    GrBackendContext getBackendContext() override { return (GrBackendContext) nullptr; }

[djsollen, 2016/06/07 16:05:29]

no need to cast the nullptr

[liyuqian, 2016/06/07 19:19:57]

If not, it won't compile...

+
+protected:
+    // Make sure the the subclass will initialize fDisplayParams.
+    // The subclass shall also set fWidth, fHeight in their constructions.
+    RasterWindowContext(const DisplayParams& params) {
+        fDisplayParams = params;
+    }
+
+    bool isGpuContext() override { return false;  }
+
+    SkImageInfo getImageInfo();

[djsollen, 2016/06/07 16:05:29]

remove this function.

[liyuqian, 2016/06/07 19:19:57]

Removed. Previously, we need this because of some very strange issues...

+
+    // The only method required to be implemented in the subclass
+    virtual void onSwapBuffers(sk_sp<SkImage> image) = 0;
+
+private:
+    sk_sp<SkSurface> fBackbufferSurface = nullptr;

[djsollen, 2016/06/07 16:05:29]

we shouldn't need to store this.

[liyuqian, 2016/06/07 19:19:57]

We need to store this because one might call getBackbufferSurface multiple times
before swapBuffers.

+};
+
+}   // namespace sk_app
+
+#endif