Implement Raster Backend on Android Viewer App

tools/viewer/sk_app/android/RasterWindowContext_android.cpp

Index: tools/viewer/sk_app/android/RasterWindowContext_android.cpp
diff --git a/tools/viewer/sk_app/android/RasterWindowContext_android.cpp b/tools/viewer/sk_app/android/RasterWindowContext_android.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3c0188f11b5439498a7da0f937570b43dcfede83
--- /dev/null
+++ b/tools/viewer/sk_app/android/RasterWindowContext_android.cpp
@@ -0,0 +1,53 @@
+
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "RasterWindowContext_android.h"
+
+#include "SkSurface.h"
+#include "SkTypes.h"
+
+#include "Window_android.h"
+
+namespace sk_app {
+
+RasterWindowContext_android::RasterWindowContext_android(
+        void* platformData, const DisplayParams& params)
+    : RasterWindowContext(params) {
+    ContextPlatformData_android* androidPlatformData =
+            reinterpret_cast<ContextPlatformData_android*>(platformData);
+    fNativeWindow = androidPlatformData->fNativeWindow;
+    fWidth = ANativeWindow_getWidth(fNativeWindow);
+    fHeight = ANativeWindow_getHeight(fNativeWindow);
+    int32_t format;
+    switch(params.fColorType) {
+        case kRGBA_8888_SkColorType:
+            format = WINDOW_FORMAT_RGBA_8888;
+            break;
+        case kRGB_565_SkColorType:
+            format = WINDOW_FORMAT_RGB_565;
+            break;
+        default:
+            SkDEBUGFAIL("Unsupported Android color type");
+    }
+    ANativeWindow_setBuffersGeometry(fNativeWindow, fWidth, fHeight, format);
+}
+
+void RasterWindowContext_android::onSwapBuffers(sk_sp<SkImage> image) {
+    SkImageInfo info = SkImageInfo::Make(fWidth, fHeight,
+                                         fDisplayParams.fColorType,
+                                         kOpaque_SkAlphaType,
+                                         fDisplayParams.fProfileType);
+    ANativeWindow_Buffer buffer;
+    ARect bounds;
+    ANativeWindow_lock(fNativeWindow, &buffer, &bounds);
+    const int bytePerPixel = buffer.format == WINDOW_FORMAT_RGB_565 ? 2 : 4;
+    image->readPixels(this->getImageInfo(), buffer.bits, buffer.stride * bytePerPixel, 0, 0);

[djsollen, 2016/06/07 16:05:30]

we should not do a pixel copy on every frame.  The getBackBufferSurface() should
be implemented here and when it is called it needs to lock the window.  This
call should just unlock and post the buffer that was locked.

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

Done.

+    ANativeWindow_unlockAndPost(fNativeWindow);
+}
+
+}   // namespace sk_app