Make thresholds configurable through props

Author: FMCorz

README.md

@@ -36,8 +36,9 @@ var ViewPager = require('react-native-viewpager');
 * **`isLoop`**: `true` to run in infinite scroll mode,
 * **`locked`**: `true` to disable touch scroll,
 * **`onChangePage`**: page change callback,
-* **`renderPageIndicator`**: render custom ViewPager indicator.
-* **`initialPage`**: show initially some other page than first page.
+* **`renderPageIndicator`**: render custom ViewPager indicator,
+* **`distanceThreshold`**: the relative screen distance at which a transition is triggered (from 0 to 1),
+* **`velocityThreshold`**: the velocity at which a transition is triggered (see [gestureState.vx](https://facebook.github.io/react-native/docs/panresponder.html)).
 
 ## Page Transition Animation Controls
 

ViewPager.js

@@ -42,6 +42,8 @@ var ViewPager = React.createClass({
     autoPlay: PropTypes.bool,
     animation: PropTypes.func,
     initialPage: PropTypes.number,
+    distanceThreshold: PropTypes.number,
+    velocityThreshold: PropTypes.number,
   },
 
   fling: false,
@@ -50,6 +52,8 @@ var ViewPager = React.createClass({
     return {
       isLoop: false,
       locked: false,
+      distanceThreshold: 0.5,
+      velocityThreshold: 1e-6,
       animation: function(animate, toValue, gs) {
         return Animated.spring(animate,
           {
@@ -78,9 +82,11 @@ var ViewPager = React.createClass({
           vx = gestureState.vx;
 
       var step = 0;
-      if (relativeGestureDistance < -0.5 || (relativeGestureDistance < 0 && vx <= -1e-6)) {
+      if (relativeGestureDistance < -this.props.distanceThreshold
+          || (relativeGestureDistance < 0 && vx <= -this.props.velocityThreshold)) {
         step = 1;
-      } else if (relativeGestureDistance > 0.5 || (relativeGestureDistance > 0 && vx >= 1e-6)) {
+      } else if (relativeGestureDistance > this.props.distanceThreshold
+          || (relativeGestureDistance > 0 && vx >= this.props.velocityThreshold)) {
         step = -1;
       }