Set threshold for hiding the bottom sheet so that dragging it down doesn't accidently dismiss it.

PiperOrigin-RevId: 274646607

Author: Material Design Team

lib/java/com/google/android/material/bottomsheet/BottomSheetBehavior.java

@@ -178,6 +178,8 @@ public abstract static class BottomSheetCallback {
 
   @SaveFlags private int saveFlags = SAVE_NONE;
 
+  private static final int SIGNIFICANT_VEL_THRESHOLD = 500;
+
   private static final float HIDE_THRESHOLD = 0.5f;
 
   private static final float HIDE_FRICTION = 0.1f;
@@ -1025,13 +1027,15 @@ private void updateDrawableForTargetState(@State int state) {
     }
   }
 
-  private void calculateCollapsedOffset() {
-    int peek;
+  private int calculatePeekHeight() {
     if (peekHeightAuto) {
-      peek = Math.max(peekHeightMin, parentHeight - parentWidth * 9 / 16);
-    } else {
-      peek = peekHeight;
+      return Math.max(peekHeightMin, parentHeight - parentWidth * 9 / 16);
     }
+    return peekHeight;
+  }
+
+  private void calculateCollapsedOffset() {
+    int peek = calculatePeekHeight();
 
     if (fitToContents) {
       collapsedOffset = Math.max(parentHeight - peek, fitToContentsOffset);
@@ -1080,8 +1084,9 @@ boolean shouldHide(@NonNull View child, float yvel) {
       // It should not hide, but collapse.
       return false;
     }
+    int peek = calculatePeekHeight();
     final float newTop = child.getTop() + yvel * HIDE_FRICTION;
-    return Math.abs(newTop - collapsedOffset) / (float) peekHeight > HIDE_THRESHOLD;
+    return Math.abs(newTop - collapsedOffset) / (float) peek > HIDE_THRESHOLD;
   }
 
   @Nullable
@@ -1228,6 +1233,11 @@ public void onViewDragStateChanged(int state) {
           }
         }
 
+        private boolean releasedLow(@NonNull View child) {
+          // Needs to be at least half way to the bottom.
+          return child.getTop() > (parentHeight + getExpandedOffset()) / 2;
+        }
+
         @Override
         public void onViewReleased(@NonNull View releasedChild, float xvel, float yvel) {
           int top;
@@ -1246,13 +1256,24 @@ public void onViewReleased(@NonNull View releasedChild, float xvel, float yvel)
                 targetState = STATE_EXPANDED;
               }
             }
-          } else if (hideable
-              && shouldHide(releasedChild, yvel)
-              && (releasedChild.getTop() > collapsedOffset || Math.abs(xvel) < Math.abs(yvel))) {
-            // Hide if we shouldn't collapse and the view was either released low or it was a
-            // vertical swipe.
-            top = parentHeight;
-            targetState = STATE_HIDDEN;
+          } else if (hideable && shouldHide(releasedChild, yvel)) {
+            // Hide if the view was either released low or it was a significant vertical swipe
+            // otherwise settle to closest expanded state.
+            if ((Math.abs(xvel) < Math.abs(yvel) && yvel > SIGNIFICANT_VEL_THRESHOLD)
+                || releasedLow(releasedChild)) {
+              top = parentHeight;
+              targetState = STATE_HIDDEN;
+            } else if (fitToContents) {
+              top = fitToContentsOffset;
+              targetState = STATE_EXPANDED;
+            } else if (Math.abs(releasedChild.getTop() - expandedOffset)
+                < Math.abs(releasedChild.getTop() - halfExpandedOffset)) {
+              top = expandedOffset;
+              targetState = STATE_EXPANDED;
+            } else {
+              top = halfExpandedOffset;
+              targetState = STATE_HALF_EXPANDED;
+            }
           } else if (yvel == 0.f || Math.abs(xvel) > Math.abs(yvel)) {
             // If the Y velocity is 0 or the swipe was mostly horizontal indicated by the X velocity
             // being greater than the Y velocity, settle to the nearest correct height.
@@ -1331,7 +1352,7 @@ void dispatchOnSlide(int top) {
     View bottomSheet = viewRef.get();
     if (bottomSheet != null && !callbacks.isEmpty()) {
       float slideOffset =
-          (top > collapsedOffset)
+          (top > collapsedOffset || collapsedOffset == getExpandedOffset())
               ? (float) (collapsedOffset - top) / (parentHeight - collapsedOffset)
               : (float) (collapsedOffset - top) / (collapsedOffset - getExpandedOffset());
       for (int i = 0; i < callbacks.size(); i++) {

tests/javatests/com/google/android/material/bottomsheet/BottomSheetBehaviorTest.java

@@ -428,6 +428,79 @@ public void testSkipCollapsedFullyExpanded() throws Throwable {
     testSkipCollapsed();
   }
 
+  private void testSkipCollapsed_smallSwipe(int expectedState, float swipeViewHeightPercentage)
+      throws Throwable {
+    getBehavior().setSkipCollapsed(true);
+    checkSetState(BottomSheetBehavior.STATE_EXPANDED, ViewMatchers.isDisplayed());
+    Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
+        .perform(
+            DesignViewActions.withCustomConstraints(
+                new GeneralSwipeAction(
+                    Swipe.SLOW,
+                    // Manually calculate the starting coordinates to make sure that the touch
+                    // actually falls onto the view on Gingerbread
+                    view -> {
+                      int[] location = new int[2];
+                      view.getLocationInWindow(location);
+                      return new float[] {view.getWidth() / 2, location[1] + 1};
+                    },
+                    // Manually calculate the ending coordinates to make sure that the bottom
+                    // sheet is collapsed, not hidden
+                    view -> {
+                      return new float[] {
+                        // x: center of the bottom sheet
+                        view.getWidth() / 2,
+                        // y: some percentage down the view
+                        view.getHeight() * swipeViewHeightPercentage,
+                      };
+                    },
+                    Press.FINGER),
+                ViewMatchers.isDisplayingAtLeast(5)));
+    registerIdlingResourceCallback();
+    try {
+      if (expectedState == BottomSheetBehavior.STATE_HIDDEN) {
+        Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
+            .check(ViewAssertions.matches(not(ViewMatchers.isDisplayed())));
+      } else {
+        Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
+            .check(ViewAssertions.matches(ViewMatchers.isDisplayed()));
+      }
+      assertThat(getBehavior().getState(), is(expectedState));
+    } finally {
+      unregisterIdlingResourceCallback();
+    }
+  }
+
+  @Test
+  @MediumTest
+  public void testSkipCollapsed_smallSwipe_remainsExpanded() throws Throwable {
+    testSkipCollapsed_smallSwipe(
+        BottomSheetBehavior.STATE_EXPANDED, /* swipeViewHeightPercentage = */ 0.5f);
+  }
+
+  @Test
+  @MediumTest
+  public void testSkipCollapsedFullyExpanded_smallSwipe_remainsExpanded() throws Throwable {
+    getBehavior().setFitToContents(false);
+    testSkipCollapsed_smallSwipe(
+        BottomSheetBehavior.STATE_HALF_EXPANDED, /* swipeViewHeightPercentage = */ 0.5f);
+  }
+
+  @Test
+  @MediumTest
+  public void testSkipCollapsed_smallSwipePastThreshold_getsHidden() throws Throwable {
+    testSkipCollapsed_smallSwipe(
+        BottomSheetBehavior.STATE_HIDDEN, /* swipeViewHeightPercentage = */ 0.75f);
+  }
+
+  @Test
+  @MediumTest
+  public void testSkipCollapsedFullyExpanded_smallSwipePastThreshold_getsHidden() throws Throwable {
+    getBehavior().setFitToContents(false);
+    testSkipCollapsed_smallSwipe(
+        BottomSheetBehavior.STATE_HIDDEN, /* swipeViewHeightPercentage = */ 0.75f);
+  }
+
   @Test
   @MediumTest
   public void testSwipeUpToExpand() {