From a5e0b31f0212aeb98db86fd91b2faa5b27c108f8 Mon Sep 17 00:00:00 2001
From: Dario Thornhill <dario.thornhill@gmail.com>
Date: Wed, 2 Sep 2020 07:17:51 +0200
Subject: [PATCH] Added onSnapReached prop which runs a given callback passing
 to it the index of the running snappingPoint and it's height.

---
 SlidingUpPanel.js | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/SlidingUpPanel.js b/SlidingUpPanel.js
index 270ae65..2978cab 100644
--- a/SlidingUpPanel.js
+++ b/SlidingUpPanel.js
@@ -51,6 +51,7 @@ class SlidingUpPanel extends React.PureComponent {
     onMomentumDragStart: PropTypes.func,
     onMomentumDragEnd: PropTypes.func,
     onBottomReached: PropTypes.func,
+    onSnapReached: PropTypes.func,
     allowMomentum: PropTypes.bool,
     allowDragging: PropTypes.bool,
     showBackdrop: PropTypes.bool,
@@ -80,6 +81,7 @@ class SlidingUpPanel extends React.PureComponent {
     backdropOpacity: 0.75,
     friction: Constants.DEFAULT_FRICTION,
     onBottomReached: () => null,
+    onSnapReached: () => null,
   }
 
   // eslint-disable-next-line react/sort-comp
@@ -282,11 +284,16 @@ class SlidingUpPanel extends React.PureComponent {
 
   _onAnimatedValueChange({value}) {
     const isAtBottom = this._isAtBottom(value)
+    const isAtSnap = this._isAtSnap(value)
 
     if (isAtBottom) {
       this.props.onBottomReached()
       this.props.avoidKeyboard && Keyboard.dismiss()
     }
+    if (isAtSnap > -1 && !isAtBottom) {
+      this.props.onSnapReached(isAtSnap, value);
+      this.props.avoidKeyboard && Keyboard.dismiss()
+    }
 
     if (this._backdrop == null) {
       return
@@ -369,6 +376,15 @@ class SlidingUpPanel extends React.PureComponent {
     return value <= bottom
   }
 
+  _isAtSnap(value) {
+    const snappingPoints= this.props.snappingPoints;
+    let found = -1;
+    if (snappingPoints) {
+      found = snappingPoints.findIndex((point) => point === value);
+    }
+    return found;
+  }
+
   _storeKeyboardPosition(value) {
     this._keyboardYPosition = value
   }