Move inval dedup to Window for wider usages.

tools/viewer/sk_app/Window.h

Index: tools/viewer/sk_app/Window.h
diff --git a/tools/viewer/sk_app/Window.h b/tools/viewer/sk_app/Window.h
index 63d5e19e5594716c9bc95742b0fac51fe8b9af75..4db907e765655db81885ac8650827423b946af58 100644
--- a/tools/viewer/sk_app/Window.h
+++ b/tools/viewer/sk_app/Window.h
@@ -12,6 +12,7 @@
 #include "SkRect.h"
 #include "SkTouchGesture.h"
 #include "SkTypes.h"
+#include "../private/SkMutex.h"
 
 class SkCanvas;
 
@@ -27,8 +28,17 @@ public:
 
     virtual void setTitle(const char*) = 0;
     virtual void show() = 0;
+
+    // Make sure that either onPaint or uncheckInval is called in the subclasses' implementations
+    // of inval. They unset fIsContentInvalided which allow checkAndInval to invalidate the content
+    // in the future.
     virtual void inval() = 0;

[djsollen, 2016/05/23 15:22:42]

make this protected

[liyuqian, 2016/05/23 15:49:25]

Done.

 
+    // Check if the current window has any pending inval; call inval if not.
+    void checkAndInval();
+    // Uncheck fIsContentInvalided to allow future checkAndInval to push inval events.
+    void uncheckInval();

[djsollen, 2016/05/23 15:22:42]

make this protected. I also find this naming confusing.  How about...

public:
  void inval();
protected:
  virtual void onInval() = 0;
  void markInvalReceived();

[liyuqian, 2016/05/23 15:49:25]

I don't want to change inval's name because it's implemented in many places and
let it be the name for another purpose is very confusing... Maybe renaming
checkAndInval to invalIfNeeded and putting inval in protected is clear enough?

Also, I'd prefer markInvalProcessed and make it public because other classes
have to call it.

+
     virtual bool scaleContentToFit() const { return false; }
     virtual bool supportsContentRect() const { return false; }
     virtual SkRect getContentRect() { return SkRect::MakeEmpty(); }
@@ -164,6 +174,8 @@ protected:
     void*        fPaintUserData;
 
     WindowContext* fWindowContext = nullptr;
+
+    bool fIsContentInvalidated = false;  // use this to avoid duplicate invalidate events
 };
 
 }   // namespace sk_app