Bound the maximum touchscreen fling velocity.

Set a configurable cap on the maximum touchscreen fling velocity.

BUG=141653


Review URL: https://chromiumcodereview.appspot.com/11299276

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170761 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 27 insertions, 6 deletions

diff --git a/chrome/browser/resources/gesture_config.js b/chrome/browser/resources/gesture_config.js
index 25e9ce6..74607f9 100644
--- a/chrome/browser/resources/gesture_config.js
+++ b/chrome/browser/resources/gesture_config.js
@@ -244,6 +244,11 @@ function GestureConfig() {
       key: 'fling_acceleration_curve_coefficient_3',
       label: '+',
       units: 'x<sup>0</sup>'
+    },
+    {
+      key: 'fling_velocity_cap',
+      label: 'Touchscreen Fling Velocity Cap',
+      units: 'pixels / second'
     }
   ];
 
diff --git a/chrome/browser/ui/gesture_prefs_observer_factory_aura.cc b/chrome/browser/ui/gesture_prefs_observer_factory_aura.cc
index 5669fc7..d52ecc1 100644
--- a/chrome/browser/ui/gesture_prefs_observer_factory_aura.cc
+++ b/chrome/browser/ui/gesture_prefs_observer_factory_aura.cc
@@ -78,6 +78,7 @@ const char* kPrefsToObserve[] = {
   prefs::kFlingAccelerationCurveCoefficient1,
   prefs::kFlingAccelerationCurveCoefficient2,
   prefs::kFlingAccelerationCurveCoefficient3,
+  prefs::kFlingVelocityCap,
   prefs::kLongPressTimeInSeconds,
   prefs::kMaxDistanceForTwoFingerTapInPixels,
   prefs::kMaxSecondsBetweenDoubleClick,
@@ -136,6 +137,8 @@ void GesturePrefsObserver::Update() {
       prefs_->GetDouble(prefs::kFlingAccelerationCurveCoefficient2));
   GestureConfiguration::set_fling_acceleration_curve_coefficients(3,
       prefs_->GetDouble(prefs::kFlingAccelerationCurveCoefficient3));
+  GestureConfiguration::set_fling_velocity_cap(
+      prefs_->GetDouble(prefs::kFlingVelocityCap));
   GestureConfiguration::set_long_press_time_in_seconds(
       prefs_->GetDouble(
           prefs::kLongPressTimeInSeconds));
@@ -256,6 +259,10 @@ void GesturePrefsObserverFactoryAura::RegisterUserPrefs(PrefService* prefs) {
       GestureConfiguration::fling_acceleration_curve_coefficients(3),
       PrefService::UNSYNCABLE_PREF);
   prefs->RegisterDoublePref(
+      prefs::kFlingVelocityCap,
+      GestureConfiguration::fling_velocity_cap(),
+      PrefService::UNSYNCABLE_PREF);
+  prefs->RegisterDoublePref(
       prefs::kLongPressTimeInSeconds,
       GestureConfiguration::long_press_time_in_seconds(),
       PrefService::UNSYNCABLE_PREF);
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 5b232fa..ebdabfaf 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -2087,6 +2087,7 @@ const char kPinnedLauncherApps[] =
 // Boolean value indicating whether to show a logout button in the ash tray.
 const char kShowLogoutButtonInTray[] = "show_logout_button_in_tray";
 
+const char kFlingVelocityCap[] = "gesture.fling_velocity_cap";
 const char kLongPressTimeInSeconds[] =
     "gesture.long_press_time_in_seconds";
 const char kMaxDistanceBetweenTapsForDoubleTap[] =
diff --git a/chrome/common/pref_names.h b/chrome/common/pref_names.h
index d713440..db09c6d 100644
--- a/chrome/common/pref_names.h
+++ b/chrome/common/pref_names.h
@@ -761,6 +761,7 @@ extern const char kUseDefaultPinnedApps[];
 extern const char kPinnedLauncherApps[];
 extern const char kShowLogoutButtonInTray[];
 
+extern const char kFlingVelocityCap[];
 extern const char kLongPressTimeInSeconds[];
 extern const char kMaxDistanceBetweenTapsForDoubleTap[];
 extern const char kMaxDistanceForTwoFingerTapInPixels[];
diff --git a/ui/aura/test/aura_test_base.cc b/ui/aura/test/aura_test_base.cc
index 6e99dd5..9d0c96c6 100644
--- a/ui/aura/test/aura_test_base.cc
+++ b/ui/aura/test/aura_test_base.cc
@@ -54,6 +54,7 @@ void AuraTestBase::SetUp() {
       2, 0.0452381f);
   ui::GestureConfiguration::set_fling_acceleration_curve_coefficients(
       3, 0.8f);
+  ui::GestureConfiguration::set_fling_velocity_cap(15000.0f);
 
   helper_.reset(new AuraTestHelper(&message_loop_));
   helper_->SetUp();
diff --git a/ui/base/gestures/gesture_configuration.cc b/ui/base/gestures/gesture_configuration.cc
index 8310ed8..39847830 100644
--- a/ui/base/gestures/gesture_configuration.cc
+++ b/ui/base/gestures/gesture_configuration.cc
@@ -6,12 +6,8 @@
 
 namespace ui {
 
-// Ordered alphabetically ignoring underscores, to align with the
-// associated list of prefs in gesture_prefs_aura.cc.
-// NOTE: When updating values here, also update
-// browser/resources/gesture_config.js for chrome://gesture config UI.
-// TODO(rbyers) unify these - crbug.com/156392
 int GestureConfiguration::default_radius_ = 15;
+float GestureConfiguration::fling_velocity_cap_ = 17000.0f;
 double GestureConfiguration::long_press_time_in_seconds_ = 1.0;
 double GestureConfiguration::semi_long_press_time_in_seconds_ = 0.4;
 double GestureConfiguration::max_distance_for_two_finger_tap_in_pixels_ = 300;
diff --git a/ui/base/gestures/gesture_configuration.h b/ui/base/gestures/gesture_configuration.h
index 256c5d2..2fc5470 100644
--- a/ui/base/gestures/gesture_configuration.h
+++ b/ui/base/gestures/gesture_configuration.h
@@ -149,6 +149,12 @@ class UI_EXPORT GestureConfiguration {
   static float fling_acceleration_curve_coefficients(int i) {
     return fling_acceleration_curve_coefficients_[i];
   }
+  static float fling_velocity_cap() {
+    return fling_velocity_cap_;
+  }
+  static void set_fling_velocity_cap(float val) {
+    fling_velocity_cap_ = val;
+  }
 
  private:
   // These are listed in alphabetical order ignoring underscores, to
@@ -187,6 +193,7 @@ class UI_EXPORT GestureConfiguration {
   static double rail_break_proportion_;
   static double rail_start_proportion_;
   static float fling_acceleration_curve_coefficients_[NumAccelParams];
+  static float fling_velocity_cap_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureConfiguration);
 };
diff --git a/ui/base/gestures/gesture_sequence.cc b/ui/base/gestures/gesture_sequence.cc
index 115229a..07d42ed 100644
--- a/ui/base/gestures/gesture_sequence.cc
+++ b/ui/base/gestures/gesture_sequence.cc
@@ -296,7 +296,10 @@ float CalibrateFlingVelocity(float velocity) {
     nu += x * a;
     x *= normalized_velocity;
   }
-  return nu * velocity;
+  if (velocity < 0.f)
+    return std::max(nu * velocity, -GestureConfiguration::fling_velocity_cap());
+  else
+    return std::min(nu * velocity, GestureConfiguration::fling_velocity_cap());
 }
 
 }  // namespace