Provide max gesture bounds and option to ignore touch size during pinch

Certain devices produce garbage |MotionEvent.getTouchMajor()| values, either
unreasonably small or unreasonable large, with extreme variance between touches.
This can cause a number of problems with the current gesture detection pipeline.

Add a maximum gesture bounds size as a sanity fallback for tap disambiguation.
Also disable by default the use of touch size when calculating the pinch scale
factor. Its use does not seem to add any measurable benefit, but can produce
severe scale artifacts on devices with unpredictable touch sizes. This
phenomenon appears to be more common on devices originally targetted for ICS.

BUG=376618

Review URL: https://codereview.chromium.org/340343013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@281078 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 9 insertions, 0 deletions

diff --git a/ui/android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java b/ui/android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java
index e8fc5b9..8f47717 100644
--- a/ui/android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java
+++ b/ui/android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java
@@ -8,6 +8,7 @@ import android.content.ComponentCallbacks;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.content.res.Resources;
+import android.os.Build;
 import android.util.TypedValue;
 import android.view.ViewConfiguration;
 
@@ -136,6 +137,14 @@ public class ViewConfigurationHelper {
     }
 
     @CalledByNative
+    private static boolean shouldUseTouchMajorInScalingSpan() {
+        // Android's ScaleGestureDetector started using touch major values in
+        // JBMR1. Many devices from versions prior report wildly inconsistent
+        // touch sizes, so disable touch major use in such scenarios.
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1;
+    }
+
+    @CalledByNative
     private static ViewConfigurationHelper createWithListener(Context context) {
         ViewConfigurationHelper viewConfigurationHelper = new ViewConfigurationHelper(context);
         viewConfigurationHelper.registerListener();