Use ViewConfiguration.getScaledTouchSlop as a default value for min distance of pan handler.

Author: kmagiera

AndroidNativeExample/app/src/main/java/com/swmansion/gesturehandler/example/MainActivity.java

@@ -165,7 +165,7 @@ public void onStateChange(PinchGestureHandler handler, int newState, int oldStat
               }
             });
 
-    registry.registerHandlerForView(largeBlock, new PanGestureHandler())
+    registry.registerHandlerForView(largeBlock, new PanGestureHandler(this))
             .setMinDy(2)
             .setMaxPointers(1)
             .setOnTouchEventListener(new OnTouchEventListener<PanGestureHandler>() {

android/lib/src/main/java/com/swmansion/gesturehandler/PanGestureHandler.java

@@ -1,14 +1,15 @@
 package com.swmansion.gesturehandler;
 
+import android.content.Context;
 import android.view.MotionEvent;
 import android.view.VelocityTracker;
+import android.view.ViewConfiguration;
 
 public class PanGestureHandler extends GestureHandler<PanGestureHandler> {
 
   private static float MIN_VALUE_IGNORE = Float.MAX_VALUE;
   private static float MAX_VALUE_IGNORE = Float.MIN_VALUE;
 
-  private static float DEFAULT_MIN_DISTANCE = 10.0f;
   private static int DEFAULT_MIN_POINTERS = 1;
   private static int DEFAULT_MAX_POINTERS = 10;
 
@@ -18,7 +19,7 @@ public class PanGestureHandler extends GestureHandler<PanGestureHandler> {
   private float mMinDeltaY = MIN_VALUE_IGNORE;
   private float mMaxDeltaX = MAX_VALUE_IGNORE;
   private float mMaxDeltaY = MAX_VALUE_IGNORE;
-  private float mMinDistSq = DEFAULT_MIN_DISTANCE * DEFAULT_MIN_DISTANCE;
+  private float mMinDistSq = MAX_VALUE_IGNORE;
   private float mMinVelocityX = MIN_VALUE_IGNORE;
   private float mMinVelocityY = MIN_VALUE_IGNORE;
   private float mMinVelocitySq = MIN_VALUE_IGNORE;
@@ -93,6 +94,13 @@ private static float getLastPointerY(MotionEvent event, boolean averageTouches)
     }
   }
 
+
+  public PanGestureHandler(Context context) {
+    ViewConfiguration vc = ViewConfiguration.get(context);
+    int touchSlop = vc.getScaledTouchSlop();
+    mMinDistSq = touchSlop * touchSlop;
+  }
+
   public PanGestureHandler setMinDx(float deltaX) {
     mMinDeltaX = deltaX;
     return this;

android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerModule.java

@@ -1,5 +1,6 @@
 package com.swmansion.gesturehandler.react;
 
+import android.content.Context;
 import android.util.SparseArray;
 import android.view.MotionEvent;
 
@@ -68,7 +69,7 @@ private abstract static class HandlerFactory<T extends GestureHandler>
 
     public abstract String getName();
 
-    public abstract T create();
+    public abstract T create(Context context);
 
     public void configure(T handler, ReadableMap config) {
       if (config.hasKey(KEY_SHOULD_CANCEL_WHEN_OUTSIDE)) {
@@ -98,7 +99,7 @@ public String getName() {
     }
 
     @Override
-    public NativeViewGestureHandler create() {
+    public NativeViewGestureHandler create(Context context) {
       return new NativeViewGestureHandler();
     }
 
@@ -132,7 +133,7 @@ public String getName() {
     }
 
     @Override
-    public TapGestureHandler create() {
+    public TapGestureHandler create(Context context) {
       return new TapGestureHandler();
     }
 
@@ -164,7 +165,7 @@ public String getName() {
     }
 
     @Override
-    public LongPressGestureHandler create() {
+    public LongPressGestureHandler create(Context context) {
       return new LongPressGestureHandler();
     }
 
@@ -189,8 +190,8 @@ public String getName() {
     }
 
     @Override
-    public PanGestureHandler create() {
-      return new PanGestureHandler();
+    public PanGestureHandler create(Context context) {
+      return new PanGestureHandler(context);
     }
 
     @Override
@@ -275,7 +276,7 @@ public String getName() {
     }
 
     @Override
-    public PinchGestureHandler create() {
+    public PinchGestureHandler create(Context context) {
       return new PinchGestureHandler();
     }
 
@@ -298,7 +299,7 @@ public String getName() {
     }
 
     @Override
-    public RotationGestureHandler create() {
+    public RotationGestureHandler create(Context context) {
       return new RotationGestureHandler();
     }
 
@@ -352,7 +353,7 @@ public void createGestureHandler(
     for (int i = 0; i < mHandlerFactories.length; i++) {
       HandlerFactory handlerFactory = mHandlerFactories[i];
       if (handlerFactory.getName().equals(handlerName)) {
-        GestureHandler handler = handlerFactory.create();
+        GestureHandler handler = handlerFactory.create(getReactApplicationContext());
         handler.setTag(handlerTag);
         handler.setOnTouchEventListener(mEventListener);
         getOrCreateRegistry().registerHandler(handler);