Implement touch control

tools/viewer/sk_app/android/surface_glue_android.h

Index: tools/viewer/sk_app/android/surface_glue_android.h
diff --git a/tools/viewer/sk_app/android/surface_glue_android.h b/tools/viewer/sk_app/android/surface_glue_android.h
index 1ce06674b9eead2ac60d6f13a5f8517f0d4797fe..7ffba3080a9644b9125fb5bae3e08dd47f2dd1cc 100644
--- a/tools/viewer/sk_app/android/surface_glue_android.h
+++ b/tools/viewer/sk_app/android/surface_glue_android.h
@@ -12,6 +12,7 @@
 
 #include <android/native_window_jni.h>
 
+#include "../private/SkMutex.h"
 #include "../Application.h"
 #include "../Window.h"
 
@@ -24,13 +25,16 @@ enum MessageType {
     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) {}
@@ -49,6 +53,10 @@ struct SkiaAndroidApp {
 
     // 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;
@@ -57,6 +65,9 @@ private:
     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();