Fix the jelly effect when scrolling the a11y floating menu.

Root cause:
The default scroll mode of RecyclerView is scrollable.

Solution:
Set OVER_SCROLL_ALWAYS when the actual height of target list exceed the
available height, otherwise OVER_SCROLL_NEVER.

Bug: 184817161
Test: atest AccessibilityFloatingMenuViewTest
Change-Id: I9a2bfd674141475e5546b1ed5450e65132ffd384

packages/SystemUI/src/com/android/systemui/accessibility/floatingmenu/AccessibilityFloatingMenuView.java

@@ -371,6 +371,7 @@ public class AccessibilityFloatingMenuView extends FrameLayout
         mAdapter.notifyDataSetChanged();
 
         updateRadiusWith(mSizeType, mRadiusType, mTargets.size());
+        updateScrollModeWith(hasExceededMaxLayoutHeight());
         setSystemGestureExclusion();
 
         fadeOut();
@@ -614,6 +615,7 @@ public class AccessibilityFloatingMenuView extends FrameLayout
         updateColor();
         updateStrokeWith(newConfig.uiMode, mAlignment);
         updateLocationWith(mAlignment, mPercentageY);
+        updateScrollModeWith(hasExceededMaxLayoutHeight());
     }
 
     @VisibleForTesting
@@ -679,6 +681,12 @@ public class AccessibilityFloatingMenuView extends FrameLayout
         mListView.setLayoutParams(layoutParams);
     }
 
+    private void updateScrollModeWith(boolean hasExceededMaxLayoutHeight) {
+        mListView.setOverScrollMode(hasExceededMaxLayoutHeight
+                ? OVER_SCROLL_ALWAYS
+                : OVER_SCROLL_NEVER);
+    }
+
     private void updateColor() {
         final int menuColorResId = R.color.accessibility_floating_menu_background;
         getMenuGradientDrawable().setColor(getResources().getColor(menuColorResId));
@@ -726,6 +734,11 @@ public class AccessibilityFloatingMenuView extends FrameLayout
         layerDrawable.setLayerInset(INDEX_MENU_ITEM, left, 0, right, 0);
     }
 
+    @VisibleForTesting
+    boolean hasExceededMaxLayoutHeight() {
+        return calculateActualLayoutHeight() > getMaxLayoutHeight();
+    }
+
     @Alignment
     private int calculateCurrentAlignment() {
         return mCurrentLayoutParams.x >= ((MIN_WINDOW_X + getMaxWindowX()) / 2)
@@ -737,6 +750,10 @@ public class AccessibilityFloatingMenuView extends FrameLayout
         return mCurrentLayoutParams.y / (float) getMaxWindowY();
     }
 
+    private int calculateActualLayoutHeight() {
+        return (mPadding + mIconHeight) * mTargets.size() + mPadding;
+    }
+
     private @DimenRes int getRadiusResId(@SizeType int sizeType, int itemCount) {
         return sizeType == SizeType.SMALL
                 ? getSmallSizeResIdWith(itemCount)
@@ -760,13 +777,16 @@ public class AccessibilityFloatingMenuView extends FrameLayout
         return new Rect(0, 0, mScreenWidth - getWindowWidth(), mScreenHeight - getWindowHeight());
     }
 
+    private int getMaxLayoutHeight() {
+        return mScreenHeight - mMargin * 2;
+    }
+
     private int getLayoutWidth() {
         return mPadding * 2 + mIconWidth;
     }
 
     private int getLayoutHeight() {
-        return Math.min(mScreenHeight - mMargin * 2,
-                (mPadding + mIconHeight) * mTargets.size() + mPadding);
+        return Math.min(getMaxLayoutHeight(), calculateActualLayoutHeight());
     }
 
     private int getWindowWidth() {

packages/SystemUI/tests/src/com/android/systemui/accessibility/floatingmenu/AccessibilityFloatingMenuViewTest.java

@@ -16,6 +16,9 @@
 
 package com.android.systemui.accessibility.floatingmenu;
 
+import static android.view.View.OVER_SCROLL_ALWAYS;
+import static android.view.View.OVER_SCROLL_NEVER;
+
 import static com.google.common.truth.Truth.assertThat;
 
 import static org.mockito.ArgumentMatchers.any;
@@ -437,6 +440,30 @@ public class AccessibilityFloatingMenuViewTest extends SysuiTestCase {
                 action -> action.getId() == R.id.action_move_to_edge_and_hide)).isTrue();
     }
 
+    @Test
+    public void onTargetsChanged_exceedAvailableHeight_overScrollAlways() {
+        final RecyclerView listView = new RecyclerView(mContext);
+        final AccessibilityFloatingMenuView menuView =
+                spy(new AccessibilityFloatingMenuView(mContext, listView));
+        doReturn(true).when(menuView).hasExceededMaxLayoutHeight();
+
+        menuView.onTargetsChanged(mTargets);
+
+        assertThat(listView.getOverScrollMode()).isEqualTo(OVER_SCROLL_ALWAYS);
+    }
+
+    @Test
+    public void onTargetsChanged_notExceedAvailableHeight_overScrollNever() {
+        final RecyclerView listView = new RecyclerView(mContext);
+        final AccessibilityFloatingMenuView menuView =
+                spy(new AccessibilityFloatingMenuView(mContext, listView));
+        doReturn(false).when(menuView).hasExceededMaxLayoutHeight();
+
+        mMenuView.onTargetsChanged(mTargets);
+
+        assertThat(mListView.getOverScrollMode()).isEqualTo(OVER_SCROLL_NEVER);
+    }
+
     @After
     public void tearDown() {
         mInterceptMotionEvent = null;