[Bottom Sheet] Add ability to disable dragging/expanding/collapsing the sheet when touching/scrolling the nested scrolling child view

PiperOrigin-RevId: 624204480

Author: dsn5ft

docs/components/BottomSheet.md

@@ -439,6 +439,7 @@ Behavior                                    | Related method(s)
 `app:behavior_skipCollapsed`                | `setSkipCollapsed`<br/>`getSkipCollapsed`                                 | `false`
 `app:behavior_fitToContents`                | `setFitToContents`<br/>`isFitToContents`                                  | `true`
 `app:behavior_draggable`                    | `setDraggable`<br/>`isDraggable`                                          | `true`
+`app:behavior_draggableOnNestedScroll`      | `setDraggableOnNestedScroll`<br/>`isDraggableOnNestedScroll`              | `true`
 `app:behavior_halfExpandedRatio`            | `setHalfExpandedRatio`<br/>`getHalfExpandedRatio`                         | `0.5`
 `app:behavior_expandedOffset`               | `setExpandedOffset`<br/>`getExpandedOffset`                               | `0dp`
 `app:behavior_significantVelocityThreshold` | `setSignificantVelocityThreshold` <br/> `getSignificantVelocityThreshold` | `500 pixels/s`

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

@@ -306,6 +306,8 @@ void onLayout(@NonNull View bottomSheet) {}
 
   private boolean draggable = true;
 
+  private boolean draggableOnNestedScroll = true;
+
   @State int state = STATE_COLLAPSED;
 
   @State int lastStableState = STATE_COLLAPSED;
@@ -398,6 +400,9 @@ public BottomSheetBehavior(@NonNull Context context, @Nullable AttributeSet attr
     setSkipCollapsed(
         a.getBoolean(R.styleable.BottomSheetBehavior_Layout_behavior_skipCollapsed, false));
     setDraggable(a.getBoolean(R.styleable.BottomSheetBehavior_Layout_behavior_draggable, true));
+    setDraggableOnNestedScroll(
+        a.getBoolean(
+            R.styleable.BottomSheetBehavior_Layout_behavior_draggableOnNestedScroll, true));
     setSaveFlags(a.getInt(R.styleable.BottomSheetBehavior_Layout_behavior_saveFlags, SAVE_NONE));
     setHalfExpandedRatio(
         a.getFloat(R.styleable.BottomSheetBehavior_Layout_behavior_halfExpandedRatio, 0.5f));
@@ -739,6 +744,9 @@ public void onNestedPreScroll(
     if (isNestedScrollingCheckEnabled() && target != scrollingChild) {
       return;
     }
+    if (!draggableOnNestedScroll && target == scrollingChild) {
+      return;
+    }
     int currentTop = child.getTop();
     int newTop = currentTop - dy;
     if (dy > 0) { // Upward
@@ -877,7 +885,7 @@ public boolean onNestedPreFling(
 
     if (isNestedScrollingCheckEnabled() && nestedScrollingChildRef != null) {
       return target == nestedScrollingChildRef.get()
-          && (state != STATE_EXPANDED
+          && ((state != STATE_EXPANDED && draggableOnNestedScroll)
               || super.onNestedPreFling(coordinatorLayout, child, target, velocityX, velocityY));
     } else {
       return false;
@@ -1170,7 +1178,7 @@ public boolean getSkipCollapsed() {
   }
 
   /**
-   * Sets whether this bottom sheet is can be collapsed/expanded by dragging. Note: When disabling
+   * Sets whether this bottom sheet can be collapsed/expanded by dragging. Note: When disabling
    * dragging, an app will require to implement a custom way to expand/collapse the bottom sheet
    *
    * @param draggable {@code false} to prevent dragging the sheet to collapse and expand
@@ -1184,6 +1192,22 @@ public boolean isDraggable() {
     return draggable;
   }
 
+  /**
+   * Sets whether this bottom sheet can be collapsed/expanded by dragging on the nested scrolling
+   * child view. Default is true.
+   *
+   * @param draggableOnNestedScroll {@code false} to prevent dragging the nested scrolling child
+   * view to collapse and expand the sheet
+   * @attr ref com.google.android.material.R.styleable#BottomSheetBehavior_Layout_behavior_draggableOnNestedScroll
+   */
+  public void setDraggableOnNestedScroll(boolean draggableOnNestedScroll) {
+    this.draggableOnNestedScroll = draggableOnNestedScroll;
+  }
+
+  public boolean isDraggableOnNestedScroll() {
+    return draggableOnNestedScroll;
+  }
+
   /*
    * Sets the velocity threshold considered significant enough to trigger a slide
    * to the next stable state.

lib/java/com/google/android/material/bottomsheet/res/values/attrs.xml

@@ -41,6 +41,9 @@
          means to expand and collapse the sheet. Attribute declaration is in
          the resources package. -->
     <attr name="behavior_draggable"/>
+    <!-- Whether this bottom sheet is draggable when the nested scrolling child
+         view is scrolled. Default is true. -->
+    <attr name="behavior_draggableOnNestedScroll" format="boolean"/>
     <!-- The ratio to be used to set the height of half-expanded state in proportion to parent, when
          fitToContents is false. Defaults to true half, 0.5, if not explicitly set. Ratio must be a
          float value between 0 and 1 and produce a half-expanded state height larger than the