Add drawer with state information

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 65e1542e2cafe310c43e828193053da42804c17e..5d5ba5da8b75b3dd38408be5e6e7ccf7a76fcc24 100644
--- a/tools/viewer/sk_app/Window.h
+++ b/tools/viewer/sk_app/Window.h
@@ -27,6 +27,7 @@ public:
 
     virtual void setTitle(const char*) = 0;
     virtual void show() = 0;
+    virtual void onStateUpdated(const char* stateJsonStr) {}  // do nothing in default

[djsollen, 2016/05/24 17:32:40]

the public API should be consistent with the one in viewer.h so I propose you
use (const Json::Value& state) as your param

[liyuqian, 2016/05/24 20:18:05]

Done.

[djsollen, 2016/05/26 18:08:40]

should this be called setState()?

 
     // Shedules an invalidation event for window if one is not currently pending.
     // Make sure that either onPaint or markInvalReceived is called when the client window consumes
@@ -110,6 +111,7 @@ public:
     typedef bool(*OnKeyFunc)(Key key, InputState state, uint32_t modifiers, void* userData);
     typedef bool(*OnMouseFunc)(int x, int y, InputState state, uint32_t modifiers, void* userData);
     typedef bool(*OnTouchFunc)(int owner, InputState state, float x, float y, void* userData);
+    typedef void(*OnSetFunc)(const SkString& stateName, const SkString& stateValue, void* userData);

[djsollen, 2016/05/24 17:32:40]

I find this naming very confusing as both the user and the app can cause changes
to the state.  I think we need a clearer way to distinguish between the two
interactions that indicates this better than onStateUpdated (for app triggered)
and onSet (for user triggered).   Any ideas on the naming?

[liyuqian, 2016/05/24 20:18:05]

Let's discuss.

     typedef void(*OnPaintFunc)(SkCanvas*, void* userData);
 
     void registerCharFunc(OnCharFunc func, void* userData) {
@@ -137,10 +139,16 @@ public:
         fTouchUserData = userData;
     }
 
+    void registerSetFunc(OnSetFunc func, void* userData) {
+        fSetFunc = func;
+        fSetUserData = userData;
+    }
+
     bool onChar(SkUnichar c, uint32_t modifiers);
     bool onKey(Key key, InputState state, uint32_t modifiers);
     bool onMouse(int x, int y, InputState state, uint32_t modifiers);
     bool onTouch(int owner, InputState state, float x, float y);  // multi-owner = multi-touch
+    void onSet(const SkString& stateName, const SkString& stateValue);

[djsollen, 2016/05/26 18:08:40]

onStateChange()

     void onPaint();
     void onResize(uint32_t width, uint32_t height);
 
@@ -164,6 +172,8 @@ protected:
     void*        fMouseUserData;
     OnTouchFunc  fTouchFunc;
     void*        fTouchUserData;
+    OnSetFunc    fSetFunc;
+    void*        fSetUserData;
     OnPaintFunc  fPaintFunc;
     void*        fPaintUserData;