Allow track to be pressed at a specific position to set the value of the slider

README.md

@@ -94,7 +94,8 @@ thumbImage            | [source](http://facebook.github.io/react-native/docs/ima
 debugTouchArea        | bool     | Yes      | false                     | Set this to true to visually see the thumb touch rect in green.
 animateTransitions    | bool     | Yes      | false                     | Set to true if you want to use the default 'spring' animation
 animationType         | string   | Yes      | 'timing'                  | Set to 'spring' or 'timing' to use one of those two types of animations with the default [animation properties](https://facebook.github.io/react-native/docs/animations.html).
-animationConfig       | object   | Yes      | undefined                 | Used to configure the animation parameters.  These are the same parameters in the [Animated library](https://facebook.github.io/react-native/docs/animations.html). 
+animationConfig       | object   | Yes      | undefined                 | Used to configure the animation parameters.  These are the same parameters in the [Animated library](https://facebook.github.io/react-native/docs/animations.html).
+trackPressable        | bool     | Yes      | false                     | Allow the value to be set at a specific position when the track is pressed
 
 
 ---

src/Slider.js

@@ -167,6 +167,11 @@ export default class Slider extends PureComponent {
      * Used to configure the animation parameters.  These are the same parameters in the Animated library.
      */
     animationConfig: PropTypes.object,
+
+    /**
+      * Allow the value to be set at a specific position when the track is pressed
+      */
+    trackPressable : PropTypes.bool,
   };
 
   static defaultProps = {
@@ -180,6 +185,7 @@ export default class Slider extends PureComponent {
     thumbTouchSize: { width: 40, height: 40 },
     debugTouchArea: false,
     animationType: 'timing',
+    trackPressable: false,
   };
 
   state = {
@@ -322,6 +328,7 @@ export default class Slider extends PureComponent {
       style,
       trackStyle,
       thumbStyle,
+      trackPressable,
       ...otherProps
     } = props;
 
@@ -332,15 +339,15 @@ export default class Slider extends PureComponent {
     e: Object /* gestureState: Object */,
   ): boolean =>
     // Should we become active when the user presses down on the thumb?
-    this._thumbHitTest(e);
+    this.props.trackPressable || this._thumbHitTest(e);
 
   _handleMoveShouldSetPanResponder(/* e: Object, gestureState: Object */): boolean {
     // Should we become active when the user moves a touch over the thumb?
     return false;
   }
 
-  _handlePanResponderGrant = (/* e: Object, gestureState: Object */) => {
-    this._previousLeft = this._getThumbLeft(this._getCurrentValue());
+  _handlePanResponderGrant = (e: Object/*, gestureState: Object */) => {
+    this._previousLeft = this.props.trackPressable ? e.nativeEvent.locationX - (this.props.thumbTouchSize.width/2) : this._getThumbLeft(this._getCurrentValue());
     this._fireChangeEvent('onSlidingStart');
   };