[BottomSheetBehavior] Add attribute for significant velocity threshold

resolves #2034 PiperOrigin-RevId: 463458591
material-components · Jul 28, 2022 · d845db8 · d845db8
1 parent e284e57
commit d845db8
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Showing 5 changed files with 62 additions and 11 deletions.
diff --git a/docs/components/BottomSheet.md b/docs/components/BottomSheet.md
@@ -407,15 +407,16 @@ Element        | Attribute             | Related method(s)                 | Def
 More info about these attributes and how to use them in the
 [setting behavior](#setting-behavior) section.
 
-Behavior                         | Related method(s)                                 | Default value
--------------------------------- | ------------------------------------------------- | -------------
-`app:behavior_peekHeight`        | `setPeekHeight`<br/>`getPeekHeight`               | `auto`
-`app:behavior_hideable`          | `setHideable`<br/>`isHideable`                    | `false` for standard<br/>`true` for modal
-`app:behavior_skipCollapsed`     | `setSkipCollapsed`<br/>`getSkipCollapsed`         | `false`
-`app:behavior_fitToContents`     | `setFitToContents`<br/>`isFitToContents`          | `true`
-`app:behavior_draggable`         | `setDraggable`<br/>`isDraggable`                  | `true`
-`app:behavior_halfExpandedRatio` | `setHalfExpandedRatio`<br/>`getHalfExpandedRatio` | `0.5`
-`app:behavior_expandedOffset`    | `setExpandedOffset`<br/>`getExpandedOffset`       | `0dp`
+Behavior                                    | Related method(s)                                                         | Default value
+------------------------------------------- | ------------------------------------------------------------------------- | -------------
+`app:behavior_peekHeight`                   | `setPeekHeight`<br/>`getPeekHeight`                                       | `auto`
+`app:behavior_hideable`                     | `setHideable`<br/>`isHideable`                                            | `false` for standard<br/>`true` for modal
+`app:behavior_skipCollapsed`                | `setSkipCollapsed`<br/>`getSkipCollapsed`                                 | `false`
+`app:behavior_fitToContents`                | `setFitToContents`<br/>`isFitToContents`                                  | `true`
+`app:behavior_draggable`                    | `setDraggable`<br/>`isDraggable`                                          | `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`
 
 To save behavior on configuration change:
 

diff --git a/lib/java/com/google/android/material/bottomsheet/BottomSheetBehavior.java b/lib/java/com/google/android/material/bottomsheet/BottomSheetBehavior.java
@@ -202,7 +202,7 @@ void onLayout(@NonNull View bottomSheet) {}
 
   @SaveFlags private int saveFlags = SAVE_NONE;
 
-  private static final int SIGNIFICANT_VEL_THRESHOLD = 500;
+  @VisibleForTesting static final int DEFAULT_SIGNIFICANT_VEL_THRESHOLD = 500;
 
   private static final float HIDE_THRESHOLD = 0.5f;
 
@@ -218,6 +218,8 @@ void onLayout(@NonNull View bottomSheet) {}
 
   private float maximumVelocity;
 
+  private int significantVelocityThreshold;
+
   /** Peek height set by the user. */
   private int peekHeight;
 
@@ -382,6 +384,11 @@ public BottomSheetBehavior(@NonNull Context context, @Nullable AttributeSet attr
               R.styleable.BottomSheetBehavior_Layout_behavior_expandedOffset, 0));
     }
 
+    setSignificantVelocityThreshold(
+        a.getInt(
+            R.styleable.BottomSheetBehavior_Layout_behavior_significantVelocityThreshold,
+            DEFAULT_SIGNIFICANT_VEL_THRESHOLD));
+
     // Reading out if we are handling padding, so we can apply it to the content.
     paddingBottomSystemWindowInsets =
         a.getBoolean(R.styleable.BottomSheetBehavior_Layout_paddingBottomSystemWindowInsets, false);
@@ -1124,6 +1131,28 @@ public boolean isDraggable() {
     return draggable;
   }
 
+  /*
+   * Sets the velocity threshold considered significant enough to trigger a slide
+   * to the next stable state.
+   *
+   * @param significantVelocityThreshold The velocity threshold that warrants a vertical swipe.
+   * @see #getSignificantVelocityThreshold()
+   * @attr ref com.google.android.material.R.styleable#BottomSheetBehavior_Layout_behavior_significantVelocityThreshold
+   */
+  public void setSignificantVelocityThreshold(int significantVelocityThreshold) {
+    this.significantVelocityThreshold = significantVelocityThreshold;
+  }
+
+  /*
+   * Returns the significant velocity threshold.
+   *
+   * @see #setSignificantVelocityThreshold(int)
+   * @attr ref com.google.android.material.R.styleable#BottomSheetBehavior_Layout_behavior_significantVelocityThreshold
+   */
+  public int getSignificantVelocityThreshold() {
+    return this.significantVelocityThreshold;
+  }
+
   /**
    * Sets save flags to be preserved in bottomsheet on configuration change.
    *
@@ -1686,7 +1715,7 @@ public void onViewReleased(@NonNull View releasedChild, float xvel, float yvel)
           } 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)
+            if ((Math.abs(xvel) < Math.abs(yvel) && yvel > significantVelocityThreshold)
                 || releasedLow(releasedChild)) {
               targetState = STATE_HIDDEN;
             } else if (fitToContents) {

diff --git a/lib/java/com/google/android/material/bottomsheet/res-public/values/public.xml b/lib/java/com/google/android/material/bottomsheet/res-public/values/public.xml
@@ -35,6 +35,7 @@
   <public name="behavior_halfExpandedRatio" type="attr"/>
   <public name="behavior_hideable" type="attr"/>
   <public name="behavior_saveFlags" type="attr"/>
+  <public name="behavior_significantVelocityThreshold" type="attr"/>
   <public name="behavior_skipCollapsed" type="attr"/>
   <public name="enableEdgeToEdge" type="attr"/>
   <public name="gestureInsetBottomIgnored" type="attr"/>

diff --git a/lib/java/com/google/android/material/bottomsheet/res/values/attrs.xml b/lib/java/com/google/android/material/bottomsheet/res/values/attrs.xml
@@ -48,6 +48,9 @@
     <!-- The top offset of the BottomSheet in the expanded-state when fitsToContent is false.
          The default value is 0, which results in the sheet matching the parent's top. -->
     <attr name="behavior_expandedOffset" format="reference|dimension"/>
+    <!-- The vertical velocity threshold considered significant enough to warrant a
+         vertical swipe. -->
+    <attr name="behavior_significantVelocityThreshold" format="dimension"/>
     <!-- Shape appearance style reference for BottomSheet. Attribute declaration is in the shape
          package. -->
      <attr name="shapeAppearance"/>

diff --git a/lib/javatests/com/google/android/material/bottomsheet/BottomSheetBehaviorTest.java b/lib/javatests/com/google/android/material/bottomsheet/BottomSheetBehaviorTest.java
@@ -17,6 +17,7 @@
 
 import com.google.android.material.test.R;
 
+import static com.google.android.material.bottomsheet.BottomSheetBehavior.DEFAULT_SIGNIFICANT_VEL_THRESHOLD;
 import static com.google.common.truth.Truth.assertThat;
 
 import android.os.Bundle;
@@ -66,6 +67,22 @@ public void createBottomSheet_withIntegerRefOffset_hasCorrectOffset() {
     assertThat(behavior.getExpandedOffset()).isEqualTo(220);
   }
 
+  @Test
+  public void setSignificantVelocityThreshold() {
+    AttributeSet attributes =
+        Robolectric.buildAttributeSet()
+            .build();
+    BottomSheetBehavior<View> behavior = new BottomSheetBehavior<>(activity, attributes);
+    // Test the default value.
+    assertThat(behavior.getSignificantVelocityThreshold())
+        .isEqualTo(DEFAULT_SIGNIFICANT_VEL_THRESHOLD);
+
+    int significantVelocityValue = 1;
+    behavior.setSignificantVelocityThreshold(significantVelocityValue);
+
+    assertThat(behavior.getSignificantVelocityThreshold()).isEqualTo(significantVelocityValue);
+  }
+
   private static class TestActivity extends AppCompatActivity {
     @Override
     protected void onCreate(Bundle bundle) {