[BottomSheet] Fix bottom sheets in EXPANDED state when the expanded height is the same as the collapsed height

Resolves #2335

PiperOrigin-RevId: 435127325

Author: drchen

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

@@ -277,6 +277,7 @@ void onLayout(@NonNull View bottomSheet) {}
   boolean hideable;
 
   private boolean skipCollapsed;
+  private boolean collapsible = true;
 
   private boolean draggable = true;
 
@@ -552,6 +553,7 @@ public boolean onLayoutChild(
     fitToContentsOffset = max(0, parentHeight - childHeight);
     calculateHalfExpandedOffset();
     calculateCollapsedOffset();
+    onOffsetsUpdated();
 
     if (state == STATE_EXPANDED) {
       ViewCompat.offsetTopAndBottom(child, getExpandedOffset());
@@ -725,10 +727,12 @@ public void onNestedPreScroll(
           consumed[1] = dy;
           ViewCompat.offsetTopAndBottom(child, -dy);
           setStateInternal(STATE_DRAGGING);
-        } else {
+        } else if (!shouldSkipCollapsed()) {
           consumed[1] = currentTop - collapsedOffset;
           ViewCompat.offsetTopAndBottom(child, -consumed[1]);
           setStateInternal(STATE_COLLAPSED);
+        } else {
+          // Do nothing, the bottom sheet should be fixed.
         }
       }
     }
@@ -871,6 +875,7 @@ public void setFitToContents(boolean fitToContents) {
     }
     // Fix incorrect expanded settings depending on whether or not we are fitting sheet to contents.
     setStateInternal((this.fitToContents && state == STATE_HALF_EXPANDED) ? STATE_EXPANDED : state);
+    onOffsetsUpdated();
 
     updateAccessibilityActions();
   }
@@ -966,6 +971,7 @@ public final void setPeekHeight(int peekHeight, boolean animate) {
   private void updatePeekHeight(boolean animate) {
     if (viewRef != null) {
       calculateCollapsedOffset();
+      onOffsetsUpdated();
       if (state == STATE_COLLAPSED) {
         V view = viewRef.get();
         if (view != null) {
@@ -1204,6 +1210,10 @@ public void setState(@StableState int state) {
       Log.w(TAG, "Cannot set state: " + state);
       return;
     }
+    if (ensureExpandedStateIfNotCollapsible(state)) {
+      // setState() will be called again.
+      return;
+    }
     final int finalState;
     if (state == STATE_HALF_EXPANDED
         && fitToContents
@@ -1278,7 +1288,7 @@ void setStateInternal(@State int state) {
       return;
     }
     this.state = state;
-    if (state == STATE_COLLAPSED
+    if ((collapsible && state == STATE_COLLAPSED)
         || state == STATE_EXPANDED
         || state == STATE_HALF_EXPANDED
         || (hideable && state == STATE_HIDDEN)) {
@@ -1352,6 +1362,19 @@ private void calculateCollapsedOffset() {
     }
   }
 
+  private void onOffsetsUpdated() {
+    collapsible = collapsedOffset != getExpandedOffset();
+    ensureExpandedStateIfNotCollapsible(state);
+  }
+
+  private boolean ensureExpandedStateIfNotCollapsible(@State int state) {
+    if (!collapsible && state == STATE_COLLAPSED) {
+      setState(STATE_EXPANDED);
+      return true;
+    }
+    return false;
+  }
+
   private void calculateHalfExpandedOffset() {
     this.halfExpandedOffset = (int) (parentHeight * (1 - halfExpandedRatio));
   }
@@ -1385,7 +1408,7 @@ private void restoreOptionalState(@NonNull SavedState ss) {
   }
 
   boolean shouldHide(@NonNull View child, float yvel) {
-    if (skipCollapsed) {
+    if (shouldSkipCollapsed()) {
       return true;
     }
     if (child.getTop() < collapsedOffset) {
@@ -1397,6 +1420,10 @@ boolean shouldHide(@NonNull View child, float yvel) {
     return Math.abs(newTop - collapsedOffset) / (float) peek > HIDE_THRESHOLD;
   }
 
+  private boolean shouldSkipCollapsed() {
+    return !collapsible || skipCollapsed;
+  }
+
   @Nullable
   @VisibleForTesting
   View findScrollingChild(View view) {

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

@@ -433,10 +433,7 @@ 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());
+  private void testSkipCollapsed_smallSwipe(int expectedState, float swipeViewHeightPercentage) {
     Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
         .perform(
             DesignViewActions.withCustomConstraints(
@@ -476,16 +473,23 @@ private void testSkipCollapsed_smallSwipe(int expectedState, float swipeViewHeig
     }
   }
 
+  private void setSkipCollapsed() throws Throwable {
+    getBehavior().setSkipCollapsed(true);
+    checkSetState(BottomSheetBehavior.STATE_EXPANDED, ViewMatchers.isDisplayed());
+  }
+
   @Test
   @MediumTest
   public void testSkipCollapsed_smallSwipe_remainsExpanded() throws Throwable {
+    setSkipCollapsed();
     testSkipCollapsed_smallSwipe(
         BottomSheetBehavior.STATE_EXPANDED, /* swipeViewHeightPercentage = */ 0.5f);
   }
 
   @Test
   @MediumTest
   public void testSkipCollapsedFullyExpanded_smallSwipe_remainsExpanded() throws Throwable {
+    setSkipCollapsed();
     getBehavior().setFitToContents(false);
     testSkipCollapsed_smallSwipe(
         BottomSheetBehavior.STATE_HALF_EXPANDED, /* swipeViewHeightPercentage = */ 0.5f);
@@ -494,18 +498,41 @@ public void testSkipCollapsedFullyExpanded_smallSwipe_remainsExpanded() throws T
   @Test
   @MediumTest
   public void testSkipCollapsed_smallSwipePastThreshold_getsHidden() throws Throwable {
+    setSkipCollapsed();
     testSkipCollapsed_smallSwipe(
         BottomSheetBehavior.STATE_HIDDEN, /* swipeViewHeightPercentage = */ 0.75f);
   }
 
   @Test
   @MediumTest
   public void testSkipCollapsedFullyExpanded_smallSwipePastThreshold_getsHidden() throws Throwable {
+    setSkipCollapsed();
     getBehavior().setFitToContents(false);
     testSkipCollapsed_smallSwipe(
         BottomSheetBehavior.STATE_HIDDEN, /* swipeViewHeightPercentage = */ 0.75f);
   }
 
+  private void makeBottomSheetNotCollapsible() {
+    // Set a peek height that equals to expanded height so it always stays EXPANDED.
+    getBehavior().setPeekHeight(5000);
+  }
+
+  @Test
+  @MediumTest
+  public void testNotCollapsible_smallSwipe_remainsExpanded() {
+    makeBottomSheetNotCollapsible();
+    testSkipCollapsed_smallSwipe(
+        BottomSheetBehavior.STATE_EXPANDED, /* swipeViewHeightPercentage = */ 0.5f);
+  }
+
+  @Test
+  @MediumTest
+  public void testNotCollapsible_smallSwipePastThreshold_getsHidden() {
+    makeBottomSheetNotCollapsible();
+    testSkipCollapsed_smallSwipe(
+        BottomSheetBehavior.STATE_HIDDEN, /* swipeViewHeightPercentage = */ 0.75f);
+  }
+
   @Test
   @MediumTest
   public void testSwipeUpToExpand() {
@@ -935,16 +962,22 @@ public void testDynamicContent() throws Throwable {
   @Test
   @MediumTest
   public void testExpandedPeekHeight() throws Throwable {
+    registerIdlingResourceCallback();
     activityTestRule.runOnUiThread(
         () -> {
           // Make the peek height as tall as the bottom sheet.
-          BottomSheetBehavior<?> behavior = getBehavior();
-          behavior.setPeekHeight(getBottomSheet().getHeight());
-          assertThat(behavior.getState(), is(BottomSheetBehavior.STATE_COLLAPSED));
+          getBehavior().setPeekHeight(getBottomSheet().getHeight());
         });
-    // Both of these will not animate the sheet , but the state should be changed.
+    Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
+        .check(ViewAssertions.matches(ViewMatchers.isDisplayed()));
+    assertThat(getBehavior().getState(), is(BottomSheetBehavior.STATE_EXPANDED));
+    unregisterIdlingResourceCallback();
+    // Both of these will not animate the sheet, and the state should be fixed as EXPANDED.
     checkSetState(BottomSheetBehavior.STATE_EXPANDED, ViewMatchers.isDisplayed());
-    checkSetState(BottomSheetBehavior.STATE_COLLAPSED, ViewMatchers.isDisplayed());
+    checkSetState(
+        BottomSheetBehavior.STATE_COLLAPSED,
+        BottomSheetBehavior.STATE_EXPANDED,
+        ViewMatchers.isDisplayed());
   }
 
   @Test
@@ -962,12 +995,17 @@ public void testFindScrollingChildEnabled() {
   }
 
   private void checkSetState(final int state, Matcher<View> matcher) throws Throwable {
+    checkSetState(state, state, matcher);
+  }
+
+  private void checkSetState(
+      final int stateToSet, final int stateToExpect, Matcher<View> matcher) throws Throwable {
     registerIdlingResourceCallback();
     try {
-      activityTestRule.runOnUiThread(() -> getBehavior().setState(state));
+      activityTestRule.runOnUiThread(() -> getBehavior().setState(stateToSet));
       Espresso.onView(ViewMatchers.withId(R.id.bottom_sheet))
           .check(ViewAssertions.matches(matcher));
-      assertThat(getBehavior().getState(), is(state));
+      assertThat(getBehavior().getState(), is(stateToExpect));
       assertAccessibilityActions(getBehavior(), getBottomSheet());
     } finally {
       unregisterIdlingResourceCallback();

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

@@ -188,6 +188,9 @@ public void testHideThenShow() throws Throwable {
     final DialogInterface.OnCancelListener onCancelListener =
         mock(DialogInterface.OnCancelListener.class);
     showDialog();
+    onView(ViewMatchers.withId(R.id.design_bottom_sheet))
+        .perform(setShortPeekHeight())
+        .check(ViewAssertions.matches(ViewMatchers.isDisplayed()));
     dialog.setOnCancelListener(onCancelListener);
     onView(ViewMatchers.withId(R.id.design_bottom_sheet))
         .perform(setState(BottomSheetBehavior.STATE_HIDDEN));
@@ -205,6 +208,33 @@ public void testHideThenShow() throws Throwable {
         .onStateChanged(any(View.class), eq(BottomSheetBehavior.STATE_COLLAPSED));
   }
 
+  @Test
+  @MediumTest
+  public void testHideThenShowNotCollapsible() throws Throwable {
+    // Hide the bottom sheet and wait for the dialog to be canceled.
+    final DialogInterface.OnCancelListener onCancelListener =
+        mock(DialogInterface.OnCancelListener.class);
+    showDialog();
+    onView(ViewMatchers.withId(R.id.design_bottom_sheet))
+        .perform(setTallPeekHeight())
+        .check(ViewAssertions.matches(ViewMatchers.isDisplayed()));
+    dialog.setOnCancelListener(onCancelListener);
+    onView(ViewMatchers.withId(R.id.design_bottom_sheet))
+        .perform(setState(BottomSheetBehavior.STATE_HIDDEN));
+    verify(onCancelListener, timeout(3000)).onCancel(any(DialogInterface.class));
+    // Reshow the same dialog instance and wait for the bottom sheet to be collapsed.
+    final BottomSheetBehavior.BottomSheetCallback callback =
+        mock(BottomSheetBehavior.BottomSheetCallback.class);
+    BottomSheetBehavior.from(dialog.findViewById(R.id.design_bottom_sheet))
+        .addBottomSheetCallback(callback);
+    // Show the same dialog again.
+    activityTestRule.runOnUiThread(() -> dialog.show());
+    verify(callback, timeout(3000))
+        .onStateChanged(any(View.class), eq(BottomSheetBehavior.STATE_SETTLING));
+    verify(callback, timeout(3000))
+        .onStateChanged(any(View.class), eq(BottomSheetBehavior.STATE_EXPANDED));
+  }
+
   private void showDialog() throws Throwable {
     activityTestRule.runOnUiThread(
         () -> {
@@ -239,6 +269,26 @@ public void perform(UiController uiController, View view) {
     };
   }
 
+  private static ViewAction setShortPeekHeight() {
+    return new ViewAction() {
+      @Override
+      public Matcher<View> getConstraints() {
+        return ViewMatchers.isDisplayed();
+      }
+
+      @Override
+      public String getDescription() {
+        return "set tall peek height";
+      }
+
+      @Override
+      public void perform(UiController uiController, View view) {
+        BottomSheetBehavior<?> behavior = BottomSheetBehavior.from(view);
+        behavior.setPeekHeight(view.getHeight() / 2);
+      }
+    };
+  }
+
   private static ViewAction setState(@BottomSheetBehavior.State final int state) {
     return new ViewAction() {
       @Override