Screen Magnifier: Adds option UI and enables accelerators.

Add option UI on chrome://settings to enable & disable screen magnifier, and enable the accelerators of screen magnifier "Ctrl + brightness keys (F6/F7)".

Option UI part is almost same as the patch of high contrast mode. https://chromiumcodereview.appspot.com/10408085.

BUG=126880
TEST=manual test

Review URL: https://chromiumcodereview.appspot.com/10635019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@143841 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 49 insertions, 15 deletions

diff --git a/ash/magnifier/magnification_controller.cc b/ash/magnifier/magnification_controller.cc
index dc15483..602e95a 100644
--- a/ash/magnifier/magnification_controller.cc
+++ b/ash/magnifier/magnification_controller.cc
@@ -19,10 +19,12 @@
 
 namespace {
 
-const float kMaximumMagnifiScale = 4.0f;
-const float kMaximumMagnifiScaleThreshold = 4.0f;
-const float kMinimumMagnifiScale = 1.0f;
-const float kMinimumMagnifiScaleThreshold = 1.1f;
+const float kMaxMagnifiedScale = 4.0f;
+const float kMaxMagnifiedScaleThreshold = 4.0f;
+const float kMinMagnifiedScaleThreshold = 1.1f;
+const float kNonMagnifiedScale = 1.0f;
+
+const float kInitialMagnifiedScale = 2.0f;
 
 }  // namespace
 
@@ -40,6 +42,7 @@ class MagnificationControllerImpl : virtual public MagnificationController,
   virtual ~MagnificationControllerImpl();
 
   // MagnificationController overrides:
+  virtual void SetEnabled(bool enabled) OVERRIDE;
   virtual void SetScale(float scale, bool animate) OVERRIDE;
   virtual float GetScale() const OVERRIDE { return scale_; }
   virtual void MoveWindow(int x, int y, bool animate) OVERRIDE;
@@ -103,6 +106,8 @@ class MagnificationControllerImpl : virtual public MagnificationController,
   // Otherwise, false.
   bool is_on_zooming_;
 
+  bool is_enabled_;
+
   // Current scale, origin (left-top) position of the magnification window.
   float scale_;
   gfx::Point origin_;
@@ -116,7 +121,8 @@ class MagnificationControllerImpl : virtual public MagnificationController,
 MagnificationControllerImpl::MagnificationControllerImpl()
     : root_window_(ash::Shell::GetPrimaryRootWindow()),
       is_on_zooming_(false),
-      scale_(1.0f) {
+      is_enabled_(false),
+      scale_(kNonMagnifiedScale) {
   Shell::GetInstance()->AddEnvEventFilter(this);
 }
 
@@ -306,19 +312,19 @@ gfx::Rect MagnificationControllerImpl::GetWindowRectDIP(float scale) const {
 }
 
 bool MagnificationControllerImpl::IsMagnified() const {
-  return scale_ >= kMinimumMagnifiScaleThreshold;
+  return scale_ >= kMinMagnifiedScaleThreshold;
 }
 
 void MagnificationControllerImpl::ValidateScale(float* scale) {
-  // Adjust the scale to just |kMinimumMagnifiScale| if scale is smaller than
-  // |kMinimumMagnifiScaleThreshold|;
-  if (*scale < kMinimumMagnifiScaleThreshold)
-    *scale = kMinimumMagnifiScale;
-
-  // Adjust the scale to just |kMinimumMagnifiScale| if scale is bigger than
-  // |kMinimumMagnifiScaleThreshold|;
-  if (*scale > kMaximumMagnifiScaleThreshold)
-    *scale = kMaximumMagnifiScale;
+  // Adjust the scale to just |kNonMagnifiedScale| if scale is smaller than
+  // |kMinMagnifiedScaleThreshold|;
+  if (*scale < kMinMagnifiedScaleThreshold)
+    *scale = kNonMagnifiedScale;
+
+  // Adjust the scale to just |kMinMagnifiedScale| if scale is bigger than
+  // |kMinMagnifiedScaleThreshold|;
+  if (*scale > kMaxMagnifiedScaleThreshold)
+    *scale = kMaxMagnifiedScale;
 }
 
 void MagnificationControllerImpl::OnImplicitAnimationsCompleted() {
@@ -330,6 +336,9 @@ void MagnificationControllerImpl::OnImplicitAnimationsCompleted() {
 // MagnificationControllerImpl: MagnificationController implementation
 
 void MagnificationControllerImpl::SetScale(float scale, bool animate) {
+  if (!is_enabled_)
+    return;
+
   ValidateScale(&scale);
 
   // Try not to change the point which the mouse cursor indicates to.
@@ -341,26 +350,48 @@ void MagnificationControllerImpl::SetScale(float scale, bool animate) {
 }
 
 void MagnificationControllerImpl::MoveWindow(int x, int y, bool animate) {
+  if (!is_enabled_)
+    return;
+
   Redraw(gfx::Point(x, y), scale_, animate);
 }
 
 void MagnificationControllerImpl::MoveWindow(const gfx::Point& point,
                                              bool animate) {
+  if (!is_enabled_)
+    return;
+
   Redraw(point, scale_, animate);
 }
 
 void MagnificationControllerImpl::EnsureRectIsVisible(
     const gfx::Rect& target_rect,
     bool animate) {
+  if (!is_enabled_)
+    return;
+
   EnsureRectIsVisibleWithScale(target_rect, scale_, animate);
 }
 
 void MagnificationControllerImpl::EnsurePointIsVisible(
     const gfx::Point& point,
     bool animate) {
+  if (!is_enabled_)
+    return;
+
   EnsurePointIsVisibleWithScale(point, scale_, animate);
 }
 
+void MagnificationControllerImpl::SetEnabled(bool enabled) {
+  if (enabled) {
+    is_enabled_ = enabled;
+    SetScale(kInitialMagnifiedScale, true);
+  } else {
+    SetScale(kNonMagnifiedScale, true);
+    is_enabled_ = enabled;
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // MagnificationControllerImpl: aura::EventFilter implementation
 
diff --git a/ash/magnifier/magnification_controller.h b/ash/magnifier/magnification_controller.h
index a97d171..f392a9b 100644
--- a/ash/magnifier/magnification_controller.h
+++ b/ash/magnifier/magnification_controller.h
@@ -28,6 +28,9 @@ class MagnificationController {
   // returned object.
   static MagnificationController* CreateInstance();
 
+  // Enables (or disables if |enabled| is false) screen magnifier feature.
+  virtual void SetEnabled(bool enabled) = 0;
+
   // Sets the magnification ratio. 1.0f means no magnification.
   virtual void SetScale(float scale, bool animate) = 0;
   // Returns the current magnification ratio.