Implement touch control

tools/viewer/sk_app/android/surface_glue_android.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 surface_glue_android_DEFINED
 #define surface_glue_android_DEFINED
 
 #include <pthread.h>
 
 #include <android/native_window_jni.h>
 
+#include "../private/SkMutex.h"
 #include "../Application.h"
 #include "../Window.h"
 
 namespace sk_app {
 
 enum MessageType {
     kUndefined,
     kSurfaceCreated,
     kSurfaceChanged,
     kSurfaceDestroyed,
     kDestroyApp,
     kContentInvalidated,
-    kKeyPressed
+    kKeyPressed,
+    kTouched
 };
 
 struct Message {
     MessageType fType = kUndefined;
     ANativeWindow* fNativeWindow = nullptr;
-    int keycode = 0;
+    int fKeycode = 0;
+    int fTouchOwner, fTouchState;
+    float fTouchX, fTouchY;
 
     Message() {}
     Message(MessageType t) : fType(t) {}
 };
 
 struct SkiaAndroidApp {
     Application* fApp;
     Window* fWindow;
     jobject fAndroidApp;
 
     SkiaAndroidApp(JNIEnv* env, jobject androidApp);
 
     void postMessage(const Message& message) const;
     void readMessage(Message* message) const;
     void paintIfNeeded();
 
     // This must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
     void setTitle(const char* title) const;
+
+    // This posts a kContentInvalidated message if there's no such message currently in the queue
+    void inval();
+
 private:
     pthread_t fThread;
     ANativeWindow* fNativeWindow;
     int fPipes[2];  // 0 is the read message pipe, 1 is the write message pipe
     JavaVM* fJavaVM;
     JNIEnv* fPThreadEnv;
     jmethodID fSetTitleMethodID;
 
+    bool fIsContentInvalidated = false;  // use this to avoid duplicate invalidate events
+    SkMutex fMutex;
+
     // This must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
     ~SkiaAndroidApp();
 
     static int message_callback(int fd, int events, void* data);
     static void* pthread_main(void*);
 };
 
 }  // namespace sk_app
 
 #endif