Implement touch control

tools/viewer/sk_app/Window.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 Window_DEFINED
 #define Window_DEFINED
 
 #include "DisplayParams.h"
+#include "SkRect.h"
+#include "SkTouchGesture.h"
 #include "SkTypes.h"
-#include "SkRect.h"
 
 class SkCanvas;
 
 namespace sk_app {
 
 class WindowContext;
 
 class Window {
 public:
     static Window* CreateNativeWindow(void* platformData);
@@ skipping 68 matching lines @@
     enum InputState {
         kDown_InputState,
         kUp_InputState,
         kMove_InputState   // only valid for mouse
     };
 
     // return value of 'true' means 'I have handled this event'
     typedef bool(*OnCharFunc)(SkUnichar c, uint32_t modifiers, void* userData);
     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(*OnPaintFunc)(SkCanvas*, void* userData);
 
     void registerCharFunc(OnCharFunc func, void* userData) {
         fCharFunc = func;
         fCharUserData = userData;
     }
 
     void registerKeyFunc(OnKeyFunc func, void* userData) {
         fKeyFunc = func;
         fKeyUserData = userData;
     }
 
     void registerMouseFunc(OnMouseFunc func, void* userData) {
         fMouseFunc = func;
         fMouseUserData = userData;
     }
 
     void registerPaintFunc(OnPaintFunc func, void* userData) {
         fPaintFunc = func;
         fPaintUserData = userData;
     }
 
+    void registerTouchFunc(OnTouchFunc func, void* userData) {
+        fTouchFunc = func;
+        fTouchUserData = 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 onPaint();
     void onResize(uint32_t width, uint32_t height);
 
     uint32_t width() { return fWidth; }
     uint32_t height() { return fHeight;  }
 
     virtual const DisplayParams& getDisplayParams();
     void setDisplayParams(const DisplayParams& params);
 
 protected:
     Window();
 
     uint32_t     fWidth;
     uint32_t     fHeight;
 
     OnCharFunc   fCharFunc;
     void*        fCharUserData;
     OnKeyFunc    fKeyFunc;
     void*        fKeyUserData;
     OnMouseFunc  fMouseFunc;
     void*        fMouseUserData;
+    OnTouchFunc  fTouchFunc;
+    void*        fTouchUserData;
     OnPaintFunc  fPaintFunc;
     void*        fPaintUserData;
 
-    WindowContext* fWindowContext;
+    WindowContext* fWindowContext = nullptr;
 };
 
 }   // namespace sk_app
 #endif