Add hitSlop prop on iOS and Android

Summary:New prop `hitSlop` allows extending the touch area of Touchable components. This makes it easier to touch small buttons without needing to change your styles.

It takes `top`, `bottom`, `left`, and `right` same as the `pressRetentionOffset` prop. When a touch is moved, `hitSlop` is combined with `pressRetentionOffset` to determine how far the touch can move off the button before deactivating the button.

On Android I had to add a new file `ids.xml` to generate a unique ID to use for the tag where I store the `hitSlop` state. The iOS side is more straightforward.

terribleben worked on the iOS and JS parts of this diff.

Fixes #110
Closes https://github.com/facebook/react-native/pull/5720

Differential Revision: D2941671

Pulled By: androidtrunkagent

fb-gh-sync-id: 07e3eb8b6a36eebf76968fdaac3c6ac335603194
shipit-source-id: 07e3eb8b6a36eebf76968fdaac3c6ac335603194

Examples/UIExplorer/TouchableExample.js

@@ -93,7 +93,14 @@ exports.examples = [
     return <ForceTouchExample />;
   },
   platform: 'ios',
-}];
+}, {
+   title: 'Touchable Hit Slop',
+   description: '<Touchable*> components accept hitSlop prop which extends the touch area ' +
+     'without changing the view bounds.',
+   render: function(): ReactElement {
+     return <TouchableHitSlop />;
+   },
+ }];
 
 var TextOnPressBox = React.createClass({
   getInitialState: function() {
@@ -243,6 +250,48 @@ var ForceTouchExample = React.createClass({
   },
 });
 
+var TouchableHitSlop = React.createClass({
+  getInitialState: function() {
+    return {
+      timesPressed: 0,
+    };
+  },
+  onPress: function() {
+    this.setState({
+      timesPressed: this.state.timesPressed + 1,
+    });
+  },
+  render: function() {
+    var log = '';
+    if (this.state.timesPressed > 1) {
+      log = this.state.timesPressed + 'x onPress';
+    } else if (this.state.timesPressed > 0) {
+      log = 'onPress';
+    }
+
+    return (
+      <View testID="touchable_hit_slop">
+        <View style={[styles.row, {justifyContent: 'center'}]}>
+          <TouchableOpacity
+            onPress={this.onPress}
+            style={styles.hitSlopWrapper}
+            hitSlop={{top: 30, bottom: 30, left: 60, right: 60}}
+            testID="touchable_hit_slop_button">
+            <Text style={styles.hitSlopButton}>
+              Press Outside This View
+            </Text>
+          </TouchableOpacity>
+         </View>
+        <View style={styles.logBox}>
+          <Text>
+            {log}
+          </Text>
+        </View>
+      </View>
+    );
+  }
+});
+
 var heartImage = {uri: 'https://pbs.twimg.com/media/BlXBfT3CQAA6cVZ.png:small'};
 
 var styles = StyleSheet.create({
@@ -264,6 +313,9 @@ var styles = StyleSheet.create({
   button: {
     color: '#007AFF',
   },
+  hitSlopButton: {
+    color: 'white',
+  },
   wrapper: {
     borderRadius: 8,
   },
@@ -271,6 +323,10 @@ var styles = StyleSheet.create({
     borderRadius: 8,
     padding: 6,
   },
+  hitSlopWrapper: {
+    backgroundColor: 'red',
+    marginVertical: 30,
+  },
   logBox: {
     padding: 20,
     margin: 10,

Libraries/Components/Touchable/Touchable.js

@@ -432,6 +432,16 @@ var TouchableMixin = {
     var pressExpandRight = pressRectOffset.right;
     var pressExpandBottom = pressRectOffset.bottom;
 
+    var hitSlop = this.touchableGetHitSlop ?
+      this.touchableGetHitSlop() : null;
+
+    if (hitSlop) {
+      pressExpandLeft += hitSlop.left;
+      pressExpandTop += hitSlop.top;
+      pressExpandRight += hitSlop.right;
+      pressExpandBottom += hitSlop.bottom;
+    }
+
     var touch = TouchEventUtils.extractSingleTouch(e.nativeEvent);
     var pageX = touch && touch.pageX;
     var pageY = touch && touch.pageY;

Libraries/Components/Touchable/TouchableBounce.js

@@ -54,6 +54,15 @@ var TouchableBounce = React.createClass({
      * is disabled. Ensure you pass in a constant to reduce memory allocations.
      */
     pressRetentionOffset: EdgeInsetsPropType,
+    /**
+     * This defines how far your touch can start away from the button. This is
+     * added to `pressRetentionOffset` when moving off of the button.
+     * ** NOTE **
+     * The touch area never extends past the parent view bounds and the Z-index
+     * of sibling views always takes precedence if a touch hits two overlapping
+     * views.
+     */
+    hitSlop: EdgeInsetsPropType,
   },
 
   getInitialState: function(): State {
@@ -108,6 +117,10 @@ var TouchableBounce = React.createClass({
     return this.props.pressRetentionOffset || PRESS_RETENTION_OFFSET;
   },
 
+  touchableGetHitSlop: function(): ?Object {
+    return this.props.hitSlop;
+  },
+
   touchableGetHighlightDelayMS: function(): number {
     return 0;
   },
@@ -121,6 +134,7 @@ var TouchableBounce = React.createClass({
         accessibilityComponentType={this.props.accessibilityComponentType}
         accessibilityTraits={this.props.accessibilityTraits}
         testID={this.props.testID}
+        hitSlop={this.props.hitSlop}
         onStartShouldSetResponder={this.touchableHandleStartShouldSetResponder}
         onResponderTerminationRequest={this.touchableHandleResponderTerminationRequest}
         onResponderGrant={this.touchableHandleResponderGrant}

Libraries/Components/Touchable/TouchableHighlight.js

@@ -176,6 +176,10 @@ var TouchableHighlight = React.createClass({
     return this.props.pressRetentionOffset || PRESS_RETENTION_OFFSET;
   },
 
+  touchableGetHitSlop: function() {
+    return this.props.hitSlop;
+  },
+
   touchableGetHighlightDelayMS: function() {
     return this.props.delayPressIn;
   },
@@ -230,6 +234,7 @@ var TouchableHighlight = React.createClass({
         ref={UNDERLAY_REF}
         style={this.state.underlayStyle}
         onLayout={this.props.onLayout}
+        hitSlop={this.props.hitSlop}
         onStartShouldSetResponder={this.touchableHandleStartShouldSetResponder}
         onResponderTerminationRequest={this.touchableHandleResponderTerminationRequest}
         onResponderGrant={this.touchableHandleResponderGrant}

Libraries/Components/Touchable/TouchableNativeFeedback.android.js

@@ -162,6 +162,10 @@ var TouchableNativeFeedback = React.createClass({
     return this.props.pressRetentionOffset || PRESS_RETENTION_OFFSET;
   },
 
+  touchableGetHitSlop: function() {
+    return this.props.hitSlop;
+  },
+
   touchableGetHighlightDelayMS: function() {
     return this.props.delayPressIn;
   },
@@ -205,6 +209,7 @@ var TouchableNativeFeedback = React.createClass({
       accessibilityTraits: this.props.accessibilityTraits,
       testID: this.props.testID,
       onLayout: this.props.onLayout,
+      hitSlop: this.props.hitSlop,
       onStartShouldSetResponder: this.touchableHandleStartShouldSetResponder,
       onResponderTerminationRequest: this.touchableHandleResponderTerminationRequest,
       onResponderGrant: this.touchableHandleResponderGrant,

Libraries/Components/Touchable/TouchableOpacity.js

@@ -124,6 +124,10 @@ var TouchableOpacity = React.createClass({
     return this.props.pressRetentionOffset || PRESS_RETENTION_OFFSET;
   },
 
+  touchableGetHitSlop: function() {
+    return this.props.hitSlop;
+  },
+
   touchableGetHighlightDelayMS: function() {
     return this.props.delayPressIn || 0;
   },
@@ -160,6 +164,7 @@ var TouchableOpacity = React.createClass({
         style={[this.props.style, {opacity: this.state.anim}]}
         testID={this.props.testID}
         onLayout={this.props.onLayout}
+        hitSlop={this.props.hitSlop}
         onStartShouldSetResponder={this.touchableHandleStartShouldSetResponder}
         onResponderTerminationRequest={this.touchableHandleResponderTerminationRequest}
         onResponderGrant={this.touchableHandleResponderGrant}

Libraries/Components/Touchable/TouchableWithoutFeedback.js

@@ -80,6 +80,15 @@ var TouchableWithoutFeedback = React.createClass({
      * is disabled. Ensure you pass in a constant to reduce memory allocations.
      */
     pressRetentionOffset: EdgeInsetsPropType,
+    /**
+     * This defines how far your touch can start away from the button. This is
+     * added to `pressRetentionOffset` when moving off of the button.
+     * ** NOTE **
+     * The touch area never extends past the parent view bounds and the Z-index
+     * of sibling views always takes precedence if a touch hits two overlapping
+     * views.
+     */
+    hitSlop: EdgeInsetsPropType,
   },
 
   getInitialState: function() {
@@ -118,6 +127,10 @@ var TouchableWithoutFeedback = React.createClass({
     return this.props.pressRetentionOffset || PRESS_RETENTION_OFFSET;
   },
 
+  touchableGetHitSlop: function(): ?Object {
+    return this.props.hitSlop;
+  },
+
   touchableGetHighlightDelayMS: function(): number {
     return this.props.delayPressIn || 0;
   },
@@ -140,6 +153,7 @@ var TouchableWithoutFeedback = React.createClass({
       accessibilityTraits: this.props.accessibilityTraits,
       testID: this.props.testID,
       onLayout: this.props.onLayout,
+      hitSlop: this.props.hitSlop,
       onStartShouldSetResponder: this.touchableHandleStartShouldSetResponder,
       onResponderTerminationRequest: this.touchableHandleResponderTerminationRequest,
       onResponderGrant: this.touchableHandleResponderGrant,

Libraries/Components/View/View.js

@@ -11,6 +11,7 @@
  */
 'use strict';
 
+const EdgeInsetsPropType = require('EdgeInsetsPropType');
 const NativeMethodsMixin = require('NativeMethodsMixin');
 const PropTypes = require('ReactPropTypes');
 const React = require('React');
@@ -201,6 +202,19 @@ const View = React.createClass({
     onMoveShouldSetResponder: PropTypes.func,
     onMoveShouldSetResponderCapture: PropTypes.func,
 
+    /**
+     * This defines how far a touch event can start away from the view.
+     * Typical interface guidelines recommend touch targets that are at least
+     * 30 - 40 points/density-independent pixels. If a Touchable view has a
+     * height of 20 the touchable height can be extended to 40 with
+     * `hitSlop={{top: 10, bottom: 10, left: 0, right: 0}}`
+     * ** NOTE **
+     * The touch area never extends past the parent view bounds and the Z-index
+     * of sibling views always takes precedence if a touch hits two overlapping
+     * views.
+     */
+    hitSlop: EdgeInsetsPropType,
+
     /**
      * Invoked on mount and layout changes with
      *

React/Views/RCTView.h

@@ -90,4 +90,9 @@
  */
 @property (nonatomic, assign) RCTBorderStyle borderStyle;
 
+/**
+ *  Insets used when hit testing inside this view.
+ */
+@property (nonatomic, assign) UIEdgeInsets hitTestEdgeInsets;
+
 @end

React/Views/RCTView.m

@@ -109,6 +109,7 @@ static NSString *RCTRecursiveAccessibilityLabel(UIView *view)
     _borderBottomLeftRadius = -1;
     _borderBottomRightRadius = -1;
     _borderStyle = RCTBorderStyleSolid;
+    _hitTestEdgeInsets = UIEdgeInsetsZero;
 
     _backgroundColor = super.backgroundColor;
   }
@@ -180,6 +181,15 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithCoder:unused)
   }
 }
 
+- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
+{
+  if (UIEdgeInsetsEqualToEdgeInsets(self.hitTestEdgeInsets, UIEdgeInsetsZero)) {
+    return [super pointInside:point withEvent:event];
+  }
+  CGRect hitFrame = UIEdgeInsetsInsetRect(self.bounds, self.hitTestEdgeInsets);
+  return CGRectContainsPoint(hitFrame, point);
+}
+
 - (BOOL)accessibilityActivate
 {
   if (_onAccessibilityTap) {

React/Views/RCTViewManager.m

@@ -193,6 +193,17 @@ RCT_CUSTOM_VIEW_PROPERTY(borderStyle, RCTBorderStyle, RCTView)
     view.borderStyle = json ? [RCTConvert RCTBorderStyle:json] : defaultView.borderStyle;
   }
 }
+RCT_CUSTOM_VIEW_PROPERTY(hitSlop, UIEdgeInsets, RCTView)
+{
+  if ([view respondsToSelector:@selector(setHitTestEdgeInsets:)]) {
+    if (json) {
+      UIEdgeInsets hitSlopInsets = [RCTConvert UIEdgeInsets:json];
+      view.hitTestEdgeInsets = UIEdgeInsetsMake(-hitSlopInsets.top, -hitSlopInsets.left, -hitSlopInsets.bottom, -hitSlopInsets.right);
+    } else {
+      view.hitTestEdgeInsets = defaultView.hitTestEdgeInsets;
+    }
+  }
+}
 RCT_EXPORT_VIEW_PROPERTY(onAccessibilityTap, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(onMagicTap, RCTDirectEventBlock)
 

ReactAndroid/src/main/java/com/facebook/react/touch/ReactHitSlopView.java

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.touch;
+
+import android.graphics.Rect;
+
+import javax.annotation.Nullable;
+
+/**
+ * This interface should be implemented by all {@link View} subclasses that want to use the
+ * hitSlop prop to extend their touch areas.
+ */
+public interface ReactHitSlopView {
+
+  /**
+   * Called when determining the touch area of a view.
+   * @return A {@link Rect} representing how far to extend the touch area in each direction.
+   */
+  public @Nullable Rect getHitSlopRect();
+
+}

ReactAndroid/src/main/java/com/facebook/react/uimanager/TouchTargetHelper.java

@@ -13,12 +13,14 @@ import javax.annotation.Nullable;
 
 import android.graphics.Matrix;
 import android.graphics.PointF;
+import android.graphics.Rect;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup;
 
 import com.facebook.react.bridge.JSApplicationIllegalArgumentException;
 import com.facebook.react.bridge.UiThreadUtil;
+import com.facebook.react.touch.ReactHitSlopView;
 
 /**
  * Class responsible for identifying which react view should handle a given {@link MotionEvent}.
@@ -118,7 +120,7 @@ public class TouchTargetHelper {
       }
     }
     return viewGroup;
-}
+  }
 
   /**
    * Returns whether the touch point is within the child View
@@ -144,12 +146,24 @@ public class TouchTargetHelper {
       localX = localXY[0];
       localY = localXY[1];
     }
-    if ((localX >= 0 && localX < (child.getRight() - child.getLeft()))
-        && (localY >= 0 && localY < (child.getBottom() - child.getTop()))) {
-      outLocalPoint.set(localX, localY);
-      return true;
+    if (child instanceof ReactHitSlopView && ((ReactHitSlopView) child).getHitSlopRect() != null) {
+      Rect hitSlopRect = ((ReactHitSlopView) child).getHitSlopRect();
+      if ((localX >= -hitSlopRect.left && localX < (child.getRight() - child.getLeft()) + hitSlopRect.right)
+          && (localY >= -hitSlopRect.top && localY < (child.getBottom() - child.getTop()) + hitSlopRect.bottom)) {
+        outLocalPoint.set(localX, localY);
+        return true;
+      }
+
+      return false;
+    } else {
+      if ((localX >= 0 && localX < (child.getRight() - child.getLeft()))
+          && (localY >= 0 && localY < (child.getBottom() - child.getTop()))) {
+        outLocalPoint.set(localX, localY);
+        return true;
+      }
+
+      return false;
     }
-    return false;
   }
 
 

ReactAndroid/src/main/java/com/facebook/react/views/view/ReactViewGroup.java

@@ -23,6 +23,7 @@ import android.view.ViewGroup;
 
 import com.facebook.infer.annotation.Assertions;
 import com.facebook.react.common.annotations.VisibleForTesting;
+import com.facebook.react.touch.ReactHitSlopView;
 import com.facebook.react.touch.ReactInterceptingViewGroup;
 import com.facebook.react.touch.OnInterceptTouchEventListener;
 import com.facebook.react.uimanager.MeasureSpecAssertions;
@@ -34,7 +35,7 @@ import com.facebook.react.uimanager.ReactPointerEventsView;
  * initializes most of the storage needed for them.
  */
 public class ReactViewGroup extends ViewGroup implements
-    ReactInterceptingViewGroup, ReactClippingViewGroup, ReactPointerEventsView {
+    ReactInterceptingViewGroup, ReactClippingViewGroup, ReactPointerEventsView, ReactHitSlopView {
 
   private static final int ARRAY_CAPACITY_INCREMENT = 12;
   private static final int DEFAULT_BACKGROUND_COLOR = Color.TRANSPARENT;
@@ -87,6 +88,7 @@ public class ReactViewGroup extends ViewGroup implements
   private @Nullable View[] mAllChildren = null;
   private int mAllChildrenCount;
   private @Nullable Rect mClippingRect;
+  private @Nullable Rect mHitSlopRect;
   private PointerEvents mPointerEvents = PointerEvents.AUTO;
   private @Nullable ChildrenLayoutChangeListener mChildrenLayoutChangeListener;
   private @Nullable ReactViewBackgroundDrawable mReactBackgroundDrawable;
@@ -513,4 +515,13 @@ public class ReactViewGroup extends ViewGroup implements
     return mReactBackgroundDrawable;
   }
 
+  @Override
+  public @Nullable Rect getHitSlopRect() {
+    return mHitSlopRect;
+  }
+
+  public void setHitSlopRect(@Nullable Rect rect) {
+    mHitSlopRect = rect;
+  }
+
 }

ReactAndroid/src/main/java/com/facebook/react/views/view/ReactViewManager.java

@@ -14,6 +14,7 @@ import javax.annotation.Nullable;
 import java.util.Locale;
 import java.util.Map;
 
+import android.graphics.Rect;
 import android.os.Build;
 import android.view.View;
 
@@ -75,6 +76,20 @@ public class ReactViewManager extends ViewGroupManager<ReactViewGroup> {
     view.setBorderStyle(borderStyle);
   }
 
+  @ReactProp(name = "hitSlop")
+  public void setHitSlop(final ReactViewGroup view, @Nullable ReadableMap hitSlop) {
+    if (hitSlop == null) {
+      view.setHitSlopRect(null);
+    } else {
+      view.setHitSlopRect(new Rect(
+          (int) PixelUtil.toPixelFromDIP(hitSlop.getDouble("left")),
+          (int) PixelUtil.toPixelFromDIP(hitSlop.getDouble("top")),
+          (int) PixelUtil.toPixelFromDIP(hitSlop.getDouble("right")),
+          (int) PixelUtil.toPixelFromDIP(hitSlop.getDouble("bottom"))
+      ));
+    }
+  }
+
   @ReactProp(name = "pointerEvents")
   public void setPointerEvents(ReactViewGroup view, @Nullable String pointerEventsStr) {
     if (pointerEventsStr != null) {