Escher: Use dirty-tracking for View::redraw

Change-Id: I95da4eee9218784744ac4abc53328d3f537bede6

escher/include/escher/childless_view.h

@@ -7,7 +7,7 @@ class ChildlessView : public View {
   using View::View;
 protected:
   int numberOfSubviews() const override;
-  const View * subview(int index) const override;
+  View * subview(int index) override;
   void storeSubviewAtIndex(View * v, int index) override;
   void layoutSubviews() override;
 };

escher/include/escher/scroll_view.h

@@ -8,7 +8,7 @@ public:
   ScrollView(View * contentView);
 
   int numberOfSubviews() const override;
-  const View * subview(int index) const override;
+  View * subview(int index) override;
   void storeSubviewAtIndex(View * view, int index) override;
   void layoutSubviews() override;
 

escher/include/escher/tab_view.h

@@ -10,7 +10,7 @@ class TabView : public View {
 public:
   TabView();
   int numberOfSubviews() const override;
-  const View * subview(int index) const override;
+  View * subview(int index) override;
   void layoutSubviews() override;
 
   void addTabNamed(const char * name);

escher/include/escher/tab_view_controller.h

@@ -22,7 +22,7 @@ private:
     ContentView();
 
     int numberOfSubviews() const override;
-    const View * subview(int index) const override;
+    View * subview(int index) override;
     void storeSubviewAtIndex(View * view, int index) override;
     void layoutSubviews() override;
 

escher/include/escher/view.h

@@ -22,6 +22,7 @@ extern "C" {
 class Window;
 
 class View {
+  friend class Window;
 public:
   View();
 
@@ -30,12 +31,17 @@ public:
   //void addSubview(View * subview);
   //void removeFromSuperview();
   void setFrame(KDRect frame);
+
+  void markAsNeedingRedraw();
+  /*
+  void markAsDirty() const;
   void redraw() const;
+  */
 
   void setSubview(View * v, int index);
   KDRect bounds() const;
 #if ESCHER_VIEW_LOGGING
-  friend std::ostream &operator<<(std::ostream &os, const View &view);
+  friend std::ostream &operator<<(std::ostream &os, View &view);
 #endif
 protected:
 #if ESCHER_VIEW_LOGGING
@@ -44,15 +50,16 @@ protected:
 #endif
   virtual const Window * window() const;
   virtual int numberOfSubviews() const = 0;
-  virtual const View * subview(int index) const = 0;
+  virtual View * subview(int index) = 0;
   virtual void storeSubviewAtIndex(View * v, int index) = 0;
   virtual void layoutSubviews() = 0;
 private:
-  void redraw(KDRect rect) const;
+  void redraw(KDRect rect);
   KDRect absoluteDrawingArea() const;
 
   View * m_superview;
   KDRect m_frame;
+  bool m_needsRedraw;
   //TODO: We may want a dynamic size at some point
   /*
   static constexpr uint8_t k_maxNumberOfSubviews = 4;

escher/include/escher/window.h

@@ -6,13 +6,14 @@
 class Window : public View {
 public:
   Window();
+  void redraw();
 protected:
 #if ESCHER_VIEW_LOGGING
   const char * className() const override;
 #endif
   const Window * window() const override;
   int numberOfSubviews() const override;
-  const View * subview(int index) const override;
+  View * subview(int index) override;
   void layoutSubviews() override;
   void storeSubviewAtIndex(View * view, int index) override;
 private:

escher/src/app.cpp

@@ -17,6 +17,7 @@ void App::run() {
   while (true) {
     ion_event_t event = ion_get_event(); // This is a blocking call
     dispatchEvent(event);
+    window.redraw();
   }
 }
 

escher/src/childless_view.cpp

@@ -7,7 +7,7 @@ int ChildlessView::numberOfSubviews() const {
   return 0;
 }
 
-const View * ChildlessView::subview(int index) const {
+View * ChildlessView::subview(int index) {
   assert(false);
   return nullptr;
 }

escher/src/scroll_view.cpp

@@ -16,7 +16,7 @@ int ScrollView::numberOfSubviews() const {
   return 1;
 }
 
-const View * ScrollView::subview(int index) const {
+View * ScrollView::subview(int index) {
   assert(index == 0);
   return m_contentView;
 }

escher/src/scroll_view_indicator.cpp

@@ -34,12 +34,12 @@ void ScrollViewIndicator::drawRect(KDRect rect) const {
 
 void ScrollViewIndicator::setStart(float start) {
   m_start = start;
-  redraw();
+  markAsNeedingRedraw();
 }
 
 void ScrollViewIndicator::setEnd(float end) {
   m_end = end;
-  redraw();
+  markAsNeedingRedraw();
 }
 
 #if ESCHER_VIEW_LOGGING

escher/src/tab_view.cpp

@@ -17,7 +17,7 @@ void TabView::addTabNamed(const char * name) {
   m_cells[tabIndex].setName(name);
   m_numberOfTabs++;
   setSubview(&m_cells[tabIndex], tabIndex);
-  redraw();
+  markAsNeedingRedraw();
 }
 
 void TabView::setActiveIndex(int index) {
@@ -34,7 +34,7 @@ int TabView::numberOfSubviews() const {
   return m_numberOfTabs;
 }
 
-const View * TabView::subview(int index) const {
+View * TabView::subview(int index) {
   assert(index < m_numberOfTabs);
   return &m_cells[index];
 }

escher/src/tab_view_cell.cpp

@@ -12,12 +12,12 @@ TabViewCell::TabViewCell() :
 
 void TabViewCell::setName(const char * name) {
   m_name = name;
-  redraw();
+  markAsNeedingRedraw();
 }
 
 void TabViewCell::setActive(bool active) {
   m_active = active;
-  redraw();
+  markAsNeedingRedraw();
 }
 
 void TabViewCell::drawRect(KDRect rect) const {

escher/src/tab_view_controller.cpp

@@ -37,7 +37,7 @@ int TabViewController::ContentView::numberOfSubviews() const {
   return 2;
 }
 
-const View * TabViewController::ContentView::subview(int index) const {
+View * TabViewController::ContentView::subview(int index) {
   if (index == 0) {
     return &m_tabView;
   } else {
@@ -111,7 +111,7 @@ void TabViewController::setActiveTab(uint8_t i) {
   m_view.setActiveView(activeVC->view());
   m_view.m_tabView.setActiveIndex(i);
   m_activeChildIndex = i;
-  m_view.redraw();
+  m_view.markAsNeedingRedraw();
 }
 
 View * TabViewController::view() {

escher/src/view.cpp

@@ -5,13 +5,9 @@ extern "C" {
 
 View::View() :
   m_superview(nullptr),
-  m_frame(KDRectZero)
+  m_frame(KDRectZero),
+  m_needsRedraw(true)
 {
-  /*
-  for (uint8_t i=0; i<k_maxNumberOfSubviews; i++) {
-    m_subviews[i] = nullptr;
-  }
-  */
 }
 
 void View::drawRect(KDRect rect) const {
@@ -27,21 +23,36 @@ const Window * View::window() const {
   }
 }
 
-void View::redraw() const {
-  redraw(bounds());
+void View::markAsNeedingRedraw() {
+  // Let's mark ourself as needing redraw
+  m_needsRedraw = true;
+
+  /* And let's mark our parents as needing redraw too. The alternative would be
+   * to have a recursive getter, which would be more resilient to superview
+   * modification, but much slower too. As long as we don't change the view
+   * hierarchy, this way is easier. */
+  if (m_superview) {
+    m_superview->markAsNeedingRedraw();
+  }
 }
 
-void View::redraw(KDRect rect) const {
-  if (window() == nullptr) {
+void View::redraw(KDRect rect) {
+  /* CAUTION: do NOT call redraw directly.
+   * This may seem to work, but will not. Namely, it won't clip.
+   * Example : our superview is smaller than we are. If we redraw ourself, we
+   * will overflow our superview. */
+
+  if (window() == nullptr || !m_needsRedraw) {
     return;
   }
 
-  // Fisrt, let's draw our own content by calling drawRect
+  // First, let's draw our own content by calling drawRect
   KDSetDrawingArea(absoluteDrawingArea());
   this->drawRect(rect);
+
   // Then, let's recursively draw our children over ourself
   for (uint8_t i=0; i<numberOfSubviews(); i++) {
-    const View * subview = this->subview(i);
+    View * subview = this->subview(i);
     if (subview == nullptr) {
       continue;
     }
@@ -53,13 +64,16 @@ void View::redraw(KDRect rect) const {
       subview->redraw(intersection);
     }
   }
+
+  // Eventually, mark that we don't need to be redrawn
+  m_needsRedraw = false;
 }
 
 void View::setSubview(View * view, int index) {
   view->m_superview = this;
   storeSubviewAtIndex(view, index);
   assert(subview(index) == view);
-  redraw();
+  view->markAsNeedingRedraw();
 }
 
 /*
@@ -98,16 +112,18 @@ void View::removeFromSuperview() {
 
 void View::setFrame(KDRect frame) {
   // TODO: Return if frame is equal to m_frame
-  KDRect previousFrame = m_frame;
   m_frame = frame;
   if (m_superview != nullptr) {
     /* We have moved this view. This left a blank spot in its superview were it
-     * previously was. So let's redraw that part of the superview. */
-    m_superview->redraw(previousFrame);
+     * previously was.
+     * At this point, we know that the only area that really needs to be redrawn
+     * in the superview is the value of m_frame at the start of that method.
+     * However, let's not try to optimize too early, and let's simply mark the
+     * whole superview as needing redraw. */
+    m_superview->markAsNeedingRedraw();
   }
   layoutSubviews();
-  // The view now needs to redraw itself entirely
-  redraw();
+  markAsNeedingRedraw();
 }
 
 KDRect View::bounds() const {
@@ -141,7 +157,7 @@ void View::logAttributes(std::ostream &os) const {
   os << " frame=\"" << m_frame.x << "," << m_frame.y << "," << m_frame.width << "," << m_frame.height << "\"";
 }
 
-std::ostream &operator<<(std::ostream &os, const View &view) {
+std::ostream &operator<<(std::ostream &os, View &view) {
   os << "<" << view.className();
   view.logAttributes(os);
   os << ">";

escher/src/window.cpp

@@ -8,6 +8,10 @@ Window::Window() :
 {
 }
 
+void Window::redraw() {
+  View::redraw(bounds());
+}
+
 const Window * Window::window() const {
   return this;
 }
@@ -16,7 +20,7 @@ int Window::numberOfSubviews() const {
   return (m_contentView == nullptr ? 0 : 1);
 }
 
-const View * Window::subview(int index) const {
+View * Window::subview(int index) {
   assert(m_contentView != nullptr && index == 0);
   return m_contentView;
 }