Create a Window::Layer interface to reduce sk_app glue code

This also makes it possible to manage other parts of viewer, etc (like
the stats screen, command set, even samples) as additional layers in the
stack. For now, it just removes a lot of boilerplate.

Bug: skia:
Change-Id: Ic2f80690fc76c683b3736287dc2b738c50d38614
Reviewed-on: https://skia-review.googlesource.com/82688
Reviewed-by: Jim Van Verth <jvanverth@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

2 files changed, 57 insertions, 111 deletions

diff --git a/tools/sk_app/Window.cpp b/tools/sk_app/Window.cpp
index d7904fd8a7..436b6b9aa9 100644
--- a/tools/sk_app/Window.cpp
+++ b/tools/sk_app/Window.cpp
@@ -13,45 +13,7 @@
 
 namespace sk_app {
 
-static void default_backend_created_func(void* userData) {}
-
-static bool default_char_func(SkUnichar c, uint32_t modifiers, void* userData) {
-    return false;
-}
-
-static bool default_key_func(Window::Key key, Window::InputState state, uint32_t modifiers,
-                             void* userData) {
-    return false;
-}
-
-static bool default_mouse_func(int x, int y, Window::InputState state, uint32_t modifiers,
-                               void* userData) {
-    return false;
-}
-
-static bool default_mouse_wheel_func(float delta, uint32_t modifiers, void* userData) {
-    return false;
-}
-
-static bool default_touch_func(intptr_t owner, Window::InputState state, float x, float y,
-                               void* userData) {
-    return false;
-}
-
-static void default_ui_state_changed_func(
-        const SkString& stateName, const SkString& stateValue, void* userData) {}
-
-static void default_paint_func(SkCanvas*, void* userData) {}
-
-Window::Window() : fBackendCreatedFunc(default_backend_created_func)
-                 , fCharFunc(default_char_func)
-                 , fKeyFunc(default_key_func)
-                 , fMouseFunc(default_mouse_func)
-                 , fMouseWheelFunc(default_mouse_wheel_func)
-                 , fTouchFunc(default_touch_func)
-                 , fUIStateChangedFunc(default_ui_state_changed_func)
-                 , fPaintFunc(default_paint_func) {
-}
+Window::Window() {}
 
 void Window::detach() {
     delete fWindowContext;
@@ -59,31 +21,60 @@ void Window::detach() {
 }
 
 void Window::onBackendCreated() {
-    fBackendCreatedFunc(fBackendCreatedUserData);
+    for (int i = 0; i < fLayers.count(); ++i) {
+        fLayers[i]->onBackendCreated();
+    }
 }
 
 bool Window::onChar(SkUnichar c, uint32_t modifiers) {
-    return fCharFunc(c, modifiers, fCharUserData);
+    for (int i = fLayers.count() - 1; i >= 0; --i) {
+        if (fLayers[i]->onChar(c, modifiers)) {
+            return true;
+        }
+    }
+    return false;
 }
 
 bool Window::onKey(Key key, InputState state, uint32_t modifiers) {
-    return fKeyFunc(key, state, modifiers, fKeyUserData);
+    for (int i = fLayers.count() - 1; i >= 0; --i) {
+        if (fLayers[i]->onKey(key, state, modifiers)) {
+            return true;
+        }
+    }
+    return false;
 }
 
 bool Window::onMouse(int x, int y, InputState state, uint32_t modifiers) {
-    return fMouseFunc(x, y, state, modifiers, fMouseUserData);
+    for (int i = fLayers.count() - 1; i >= 0; --i) {
+        if (fLayers[i]->onMouse(x, y, state, modifiers)) {
+            return true;
+        }
+    }
+    return false;
 }
 
 bool Window::onMouseWheel(float delta, uint32_t modifiers) {
-    return fMouseWheelFunc(delta, modifiers, fMouseWheelUserData);
+    for (int i = fLayers.count() - 1; i >= 0; --i) {
+        if (fLayers[i]->onMouseWheel(delta, modifiers)) {
+            return true;
+        }
+    }
+    return false;
 }
 
 bool Window::onTouch(intptr_t owner, InputState state, float x, float y) {
-    return fTouchFunc(owner, state, x, y, fTouchUserData);
+    for (int i = fLayers.count() - 1; i >= 0; --i) {
+        if (fLayers[i]->onTouch(owner, state, x, y)) {
+            return true;
+        }
+    }
+    return false;
 }
 
 void Window::onUIStateChanged(const SkString& stateName, const SkString& stateValue) {
-    return fUIStateChangedFunc(stateName, stateValue, fUIStateChangedUserData);
+    for (int i = 0; i < fLayers.count(); ++i) {
+        fLayers[i]->onUIStateChanged(stateName, stateValue);
+    }
 }
 
 void Window::onPaint() {
@@ -96,7 +87,9 @@ void Window::onPaint() {
         // draw into the canvas of this surface
         SkCanvas* canvas = backbuffer->getCanvas();
 
-        fPaintFunc(canvas, fPaintUserData);
+        for (int i = 0; i < fLayers.count(); ++i) {
+            fLayers[i]->onPaint(canvas);
+        }
 
         canvas->flush();
 
diff --git a/tools/sk_app/Window.h b/tools/sk_app/Window.h
index 4d40780964..77478b598e 100644
--- a/tools/sk_app/Window.h
+++ b/tools/sk_app/Window.h
@@ -130,55 +130,23 @@ public:
         kMove_InputState   // only valid for mouse
     };
 
-    // return value of 'true' means 'I have handled this event'
-    typedef void(*OnBackendCreatedFunc)(void* userData);
-    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(*OnMouseWheelFunc)(float delta, uint32_t modifiers, void* userData);
-    typedef bool(*OnTouchFunc)(intptr_t owner, InputState state, float x, float y, void* userData);
-    typedef void(*OnUIStateChangedFunc)(
-            const SkString& stateName, const SkString& stateValue, void* userData);
-    typedef void(*OnPaintFunc)(SkCanvas*, void* userData);
-
-    void registerBackendCreatedFunc(OnBackendCreatedFunc func, void* userData) {
-        fBackendCreatedFunc = func;
-        fBackendCreatedUserData = 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 registerMouseWheelFunc(OnMouseWheelFunc func, void* userData) {
-        fMouseWheelFunc = func;
-        fMouseWheelUserData = userData;
-    }
-
-    void registerPaintFunc(OnPaintFunc func, void* userData) {
-        fPaintFunc = func;
-        fPaintUserData = userData;
-    }
-
-    void registerTouchFunc(OnTouchFunc func, void* userData) {
-        fTouchFunc = func;
-        fTouchUserData = userData;
-    }
+    class Layer {
+    public:
+        virtual ~Layer() = default;
+
+        // return value of 'true' means 'I have handled this event'
+        virtual void onBackendCreated() {}
+        virtual bool onChar(SkUnichar c, uint32_t modifiers) { return false; }
+        virtual bool onKey(Key key, InputState state, uint32_t modifiers) { return false; }
+        virtual bool onMouse(int x, int y, InputState state, uint32_t modifiers) { return false; }
+        virtual bool onMouseWheel(float delta, uint32_t modifiers) { return false; }
+        virtual bool onTouch(intptr_t owner, InputState state, float x, float y) { return false; }
+        virtual void onUIStateChanged(const SkString& stateName, const SkString& stateValue) {}
+        virtual void onPaint(SkCanvas*) {}
+    };
 
-    void registerUIStateChangedFunc(OnUIStateChangedFunc func, void* userData) {
-        fUIStateChangedFunc = func;
-        fUIStateChangedUserData = userData;
+    void pushLayer(Layer* layer) {
+        fLayers.push(layer);
     }
 
     void onBackendCreated();
@@ -207,22 +175,7 @@ public:
 protected:
     Window();
 
-    OnBackendCreatedFunc   fBackendCreatedFunc;
-    void*                  fBackendCreatedUserData;
-    OnCharFunc             fCharFunc;
-    void*                  fCharUserData;
-    OnKeyFunc              fKeyFunc;
-    void*                  fKeyUserData;
-    OnMouseFunc            fMouseFunc;
-    void*                  fMouseUserData;
-    OnMouseWheelFunc       fMouseWheelFunc;
-    void*                  fMouseWheelUserData;
-    OnTouchFunc            fTouchFunc;
-    void*                  fTouchUserData;
-    OnUIStateChangedFunc   fUIStateChangedFunc;
-    void*                  fUIStateChangedUserData;
-    OnPaintFunc            fPaintFunc;
-    void*                  fPaintUserData;
+    SkTDArray<Layer*>      fLayers;
     DisplayParams          fRequestedDisplayParams;
 
     WindowContext* fWindowContext = nullptr;