[chromecast] Allow toggling magnification by triple-tap.

If the magnification gesture is enabled, the AccessibilityManager will
listen for triple-tap events and turn on (or off) the
PartialMagnificationController.

Bug: internal b/110532350
Bug: internal b/110481596
Test: manual
Change-Id: I3e1ed53fddb1c525c0cc3b238e243f59b737323d
Reviewed-on: https://chromium-review.googlesource.com/1125038
Commit-Queue: Ryan Daum <rdaum@chromium.org>
Reviewed-by: Alex Sakhartchouk <alexst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573468}

chromecast/browser/accessibility/accessibility_manager.cc

@@ -5,6 +5,7 @@
 #include "chromecast/browser/accessibility/accessibility_manager.h"
 
 #include "chromecast/graphics/accessibility/focus_ring_controller.h"
+#include "chromecast/graphics/accessibility/partial_magnification_controller.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/wm/public/activation_client.h"
@@ -26,6 +27,9 @@ AccessibilityManager::AccessibilityManager(
   touch_exploration_manager_ = std::make_unique<TouchExplorationManager>(
       root_window, activation_client,
       accessibility_focus_ring_controller_.get());
+  triple_tap_detector_ = std::make_unique<TripleTapDetector>(root_window, this);
+  magnification_controller_ =
+      std::make_unique<PartialMagnificationController>(root_window);
 }
 
 AccessibilityManager::~AccessibilityManager() {}
@@ -79,5 +83,18 @@ aura::WindowTreeHost* AccessibilityManager::window_tree_host() const {
   return window_tree_host_;
 }
 
+void AccessibilityManager::SetMagnificationGestureEnabled(bool enabled) {
+  triple_tap_detector_->set_enabled(enabled);
+}
+
+bool AccessibilityManager::IsMagnificationGestureEnabled() const {
+  return triple_tap_detector_->enabled();
+}
+
+void AccessibilityManager::OnTripleTap(const gfx::Point& tap_location) {
+  magnification_controller_->SetEnabled(
+      !magnification_controller_->IsEnabled());
+}
+
 }  // namespace shell
 }  // namespace chromecast

chromecast/browser/accessibility/accessibility_manager.h

@@ -10,6 +10,7 @@
 
 #include "chromecast/browser/accessibility/touch_exploration_manager.h"
 #include "chromecast/graphics/accessibility/accessibility_focus_ring_controller.h"
+#include "chromecast/graphics/triple_tap_detector.h"
 
 namespace aura {
 class WindowTreeHost;
@@ -18,15 +19,16 @@ class WindowTreeHost;
 namespace chromecast {
 
 class FocusRingController;
+class MagnificationController;
 
 namespace shell {
 
 // Responsible for delegating chromecast browser process accessibility functions
 // to the responsible party.
-class AccessibilityManager {
+class AccessibilityManager : public TripleTapDetectorDelegate {
  public:
   explicit AccessibilityManager(aura::WindowTreeHost* window_tree_host);
-  ~AccessibilityManager();
+  ~AccessibilityManager() override;
 
   // Sets the focus ring color.
   void SetFocusRingColor(SkColor color);
@@ -63,12 +65,23 @@ class AccessibilityManager {
   // Get the window tree host this AccessibilityManager was created with.
   aura::WindowTreeHost* window_tree_host() const;
 
+  // Enable or disable the triple-tap gesture to turn on magnification.
+  void SetMagnificationGestureEnabled(bool enabled);
+
+  // Returns whether the magnification gesture is currently enabled.
+  bool IsMagnificationGestureEnabled() const;
+
+  // TripleTapDetectorDelegate implementation
+  void OnTripleTap(const gfx::Point& tap_location) override;
+
  private:
   std::unique_ptr<FocusRingController> focus_ring_controller_;
   std::unique_ptr<AccessibilityFocusRingController>
       accessibility_focus_ring_controller_;
   aura::WindowTreeHost* window_tree_host_;
   std::unique_ptr<TouchExplorationManager> touch_exploration_manager_;
+  std::unique_ptr<TripleTapDetector> triple_tap_detector_;
+  std::unique_ptr<MagnificationController> magnification_controller_;
 };
 
 }  // namespace shell

chromecast/graphics/accessibility/magnification_controller.h

@@ -16,6 +16,9 @@ class MagnificationController {
   // Turns magnifier feature on or off.
   virtual void SetEnabled(bool enabled) = 0;
 
+  // Returns true if magnification feature is on.
+  virtual bool IsEnabled() const = 0;
+
   // Adjust the ratio of the scale of magnification.
   virtual void SetMagnificationScale(float magnification_scale) = 0;
 };

chromecast/graphics/accessibility/partial_magnification_controller.cc

@@ -209,6 +209,10 @@ void PartialMagnificationController::SetEnabled(bool enabled) {
   SetActive(false);
 }
 
+bool PartialMagnificationController::IsEnabled() const {
+  return is_enabled_;
+}
+
 void PartialMagnificationController::SwitchTargetRootWindowIfNeeded(
     aura::Window* new_root_window) {
   if (host_widget_ &&

chromecast/graphics/accessibility/partial_magnification_controller.h

@@ -37,6 +37,8 @@ class PartialMagnificationController : public MagnificationController,
   // and active. Magnification becomes active on a finger press.
   void SetEnabled(bool enabled) override;
 
+  bool IsEnabled() const override;
+
   // Adjust the scale of magnification.
   void SetMagnificationScale(float magnification_scale) override;
 

chromecast/graphics/triple_tap_detector.cc

@@ -4,6 +4,7 @@
 
 #include "chromecast/graphics/triple_tap_detector.h"
 
+#include "base/auto_reset.h"
 #include "base/logging.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"