GestureNav: Fix AbsSeekBar thumb exclusion

Fix two issues that caused the exclusion for SeekBar thumbs to be to small and offset
from the thumb:

Account for padding and thumb offset; the thumb drawable is drawn with an offset
from the View's Canvas; the same offset must be applied when udpating the exclusion
rects.

The thumb is typically much smaller than the drag zone; the thumb rect alone doesn't
provide an appropriately large exclusion for reliably hitting it, so it is enlarged
to the height of the seek bar (up to 48dp).

Bug: 138992366
Test: manual, show exclusion zones with: adb shell setprop debug.pointerlocation.showexclusion 150 && adb shell settings put system pointer_location 1
Test: atest android.widget.AbsSeekBarTest
Change-Id: I2b670c6f3f33451bdccdfd3d75a75e90260257ff

1 files changed, 21 insertions, 0 deletions

diff --git a/core/java/android/widget/AbsSeekBar.java b/core/java/android/widget/AbsSeekBar.java
index 50bb6883b903..1db91233aefb 100644
--- a/core/java/android/widget/AbsSeekBar.java
+++ b/core/java/android/widget/AbsSeekBar.java
@@ -91,6 +91,7 @@ public abstract class AbsSeekBar extends ProgressBar {
     @UnsupportedAppUsage
     private float mDisabledAlpha;
 
+    private int mThumbExclusionMaxSize;
     private int mScaledTouchSlop;
     private float mTouchDownX;
     @UnsupportedAppUsage
@@ -170,6 +171,8 @@ public abstract class AbsSeekBar extends ProgressBar {
         applyTickMarkTint();
 
         mScaledTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
+        mThumbExclusionMaxSize = getResources().getDimensionPixelSize(
+                com.android.internal.R.dimen.seekbar_thumb_exclusion_max_size);
     }
 
     /**
@@ -762,12 +765,30 @@ public abstract class AbsSeekBar extends ProgressBar {
         }
         mGestureExclusionRects.clear();
         thumb.copyBounds(mThumbRect);
+        mThumbRect.offset(mPaddingLeft - mThumbOffset, mPaddingTop);
+        growRectTo(mThumbRect, Math.min(getHeight(), mThumbExclusionMaxSize));
         mGestureExclusionRects.add(mThumbRect);
         mGestureExclusionRects.addAll(mUserGestureExclusionRects);
         super.setSystemGestureExclusionRects(mGestureExclusionRects);
     }
 
     /**
+     * Grows {@code r} from its center such that each dimension is at least {@code minimumSize}.
+     */
+    private void growRectTo(Rect r, int minimumSize) {
+        int dy = (minimumSize - r.height()) / 2;
+        if (dy > 0) {
+            r.top -= dy;
+            r.bottom += dy;
+        }
+        int dx = (minimumSize - r.width()) / 2;
+        if (dx > 0) {
+            r.left -= dx;
+            r.right += dx;
+        }
+    }
+
+    /**
      * @hide
      */
     @Override