From 012226ba2006fee1e5226827c326f1227fc255f0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kristijan=20Tomi=C4=87?= <kristijan.tomic.st@gmail.com>
Date: Tue, 2 Mar 2021 12:18:18 +0100
Subject: [PATCH 1/2] Update ReactNativeZoomableView.js

handles double tap to zoom to center of the  the view
---
 src/ReactNativeZoomableView.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/ReactNativeZoomableView.js b/src/ReactNativeZoomableView.js
index 6387013..c823d72 100644
--- a/src/ReactNativeZoomableView.js
+++ b/src/ReactNativeZoomableView.js
@@ -515,8 +515,8 @@ class ReactNativeZoomableView extends Component {
     const nextZoomStep = this._getNextZoomStep();
 
     this._zoomToLocation(
-      e.nativeEvent.locationX,
-      e.nativeEvent.locationY,
+      0,
+      0,
       nextZoomStep,
       true
     );
@@ -567,6 +567,13 @@ class ReactNativeZoomableView extends Component {
     const currentElementWidth = originalWidth;
     const currentElementHeight = originalHeight;
 
+    if (x === 0 && y === 0) {
+      return {
+        x: 0,
+        y: 0,
+      }
+    }
+
     const returnObj = {
       x: (-x + (currentElementWidth / 2)),
       y: (-y + (currentElementHeight / 2)),

From b30217a5226429053d552709593373f0953d0e1a Mon Sep 17 00:00:00 2001
From: Simon Auer <simon@du.digital>
Date: Thu, 10 Jun 2021 08:43:53 +0200
Subject: [PATCH 2/2] added a new prop doubleTapZoomToCenter to allow zooming
 only to center

---
 README.md                      |  1 +
 src/ReactNativeZoomableView.js | 26 ++++++++++++++++++++------
 typings/index.d.ts             |  1 +
 3 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index f77ebe8..2b9febe 100644
--- a/README.md
+++ b/README.md
@@ -134,6 +134,7 @@ These options can be used to limit and change the zoom behavior.
 | maxZoom | number | Maximum possible zoom level (zoom in). Can be set to `null` to allow unlimited zooming | 1.5 |
 | minZoom | number | Minimum possible zoom level (zoom out) | 0.5 |
 | doubleTapDelay | number  | How much delay will still be recognized as double press (ms) | 300 |
+| doubleTapZoomToCenter | boolean | If true, double tapping will always zoom to center of View instead of the direction it was double tapped in
 | bindToBorders | boolean | If true, it makes sure the object stays within box borders | true |
 | zoomStep | number | How much zoom should be applied on double tap | 0.5 |
 | pinchToZoomInSensitivity | number | the level of resistance (sensitivity) to zoom in (0 - 10) - higher is less sensitive | 3 |
diff --git a/src/ReactNativeZoomableView.js b/src/ReactNativeZoomableView.js
index c823d72..3f0733d 100644
--- a/src/ReactNativeZoomableView.js
+++ b/src/ReactNativeZoomableView.js
@@ -503,26 +503,40 @@ class ReactNativeZoomableView extends Component {
    * @private
    */
   _handleDoubleTap(e, gestureState) {
+    const { onDoubleTapBefore, onDoubleTapAfter, doubleTapZoomToCenter } = this.props;
+
     // ignore more than 2 touches
     if (gestureState.numberActiveTouches > 1 || !this.props.zoomEnabled) {
       return;
     }
 
-    if (this.props.onDoubleTapBefore) {
-      this.props.onDoubleTapBefore(e, gestureState, this._getZoomableViewEventObject());
+    if (onDoubleTapBefore) {
+      onDoubleTapBefore(e, gestureState, this._getZoomableViewEventObject());
     }
 
     const nextZoomStep = this._getNextZoomStep();
 
+    // define new zoom position coordinates
+    const zoomPositionCoordinates = {
+      x: e.nativeEvent.locationX,
+      y: e.nativeEvent.locationY,
+    };
+
+    // if doubleTapZoomToCenter enabled -> always zoom to center instead
+    if (doubleTapZoomToCenter) {
+      zoomPositionCoordinates.x = 0;
+      zoomPositionCoordinates.y = 0;
+    }
+
     this._zoomToLocation(
-      0,
-      0,
+      zoomPositionCoordinates.x,
+      zoomPositionCoordinates.y,
       nextZoomStep,
       true
     );
 
-    if (this.props.onDoubleTapAfter) {
-      this.props.onDoubleTapAfter(e, gestureState, this._getZoomableViewEventObject({
+    if (onDoubleTapAfter) {
+      onDoubleTapAfter(e, gestureState, this._getZoomableViewEventObject({
         zoomLevel: nextZoomStep,
       }));
     }
diff --git a/typings/index.d.ts b/typings/index.d.ts
index 3fd8338..271c28a 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -31,6 +31,7 @@ declare module '@dudigital/react-native-zoomable-view' {
     maxZoom?: number;
     minZoom?: number;
     doubleTapDelay?: number;
+    doubleTapZoomToCenter?: boolean;
     bindToBorders?: boolean;
     zoomStep?: number;
     pinchToZoomInSensitivity?: number;