[Android] Fix minDistance being reset by partial config updates (#4347)

m-bert · web-flow · commit 2de57ac1e5ae · 2026-07-27T12:43:12.000+02:00
## Description Follow-up to #4327 On Android, `Pan`'s `updateConfig` derived `hasCustomActivationCriteria` from a local variable recomputed from the keys present in the incoming config map. Config updates can be partial a `SharedValue` used in the config sends `{ [key]: value }` through `updateGestureHandlerConfig`, which doesn't reset the handler first - so the flag reflected a single update message instead of the accumulated configuration. Any criteria-key update (velocity/offset) then hit the "custom criteria and no explicit `minDist`" branch and masked an explicitly configured `minDistance` with `Float.MAX_VALUE`, disabling distance-based activation entirely. `hasCustomActivationCriteria` is now a field on the handler, together with `hasExplicitMinDist` tracking whether `minDist` was explicitly configured; both are cleared in `resetConfig`. This mirrors how the other platforms already model this state (web: instance field + stored `minDist`; iOS: flag recomputed from stored recognizer state in `updateHasCustomActivationCriteria`), which is why they don't exhibit the bug. Full-config paths (`createGestureHandler` / `setGestureHandlerConfig`) go through `resetConfig` first, so their behavior is unchanged. ## Test plan <details> <summary>Tested on the following code:</summary> ```tsx import React, { useState } from 'react'; import { Button, StyleSheet, Text, View } from 'react-native'; import { GestureDetector, usePanGesture } from 'react-native-gesture-handler'; import { useSharedValue } from 'react-native-reanimated'; export default function MinDistReset() { const [log, setLog] = useState<string[]>([]); const minVelocityY = useSharedValue(10000); const append = (entry: string) => setLog((prev) => [...prev.slice(-8), entry]); const pan = usePanGesture({ minDistance: 50, minVelocityY, runOnJS: true, onActivate: () => { append('ACTIVATED'); }, onFinalize: (e) => { if (e.canceled) { append('finished without activation'); } }, }); return ( <View style={styles.container}> <Text style={styles.title}> minDistance = 50, minVelocityY = SharedValue(10000) </Text> <Text style={styles.hint}> Slow 50pt+ drag should ACTIVATE — also after poking the shared value. </Text> <Button title="poke shared value" onPress={() => { // Render-silent on purpose - see the note at the top of the file. minVelocityY.value = minVelocityY.value === 9000 ? 9001 : 9000; console.log('poked: minVelocityY ->', minVelocityY.value); }} /> <GestureDetector gesture={pan}> <View style={styles.box} testID="panBox"> <Text style={styles.boxLabel}>drag here</Text> </View> </GestureDetector> <View style={styles.log}> {log.map((entry, i) => ( <Text key={i} style={styles.logLine}> {entry} </Text> ))} </View> </View> ); } const styles = StyleSheet.create({ container: { flex: 1, alignItems: 'center', paddingTop: 16, }, title: { fontSize: 16, fontWeight: 'bold', }, hint: { textAlign: 'center', marginVertical: 12, color: '#666', }, box: { width: 300, height: 300, backgroundColor: 'tomato', borderRadius: 16, justifyContent: 'center', alignItems: 'center', marginTop: 12, }, boxLabel: { color: 'white', fontSize: 18, }, log: { marginTop: 20, minHeight: 160, alignSelf: 'stretch', paddingHorizontal: 24, }, logLine: { fontFamily: 'monospace', fontSize: 13, }, }); ``` </details>
diff --git a/packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/core/PanGestureHandler.kt b/packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/core/PanGestureHandler.kt
@@ -27,6 +27,12 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
 
   private val defaultMinDist: Float
   private var minDist = MAX_VALUE_IGNORE
+
+  // Config updates may be partial (e.g. a single key sent when a shared value used in the config
+  // changes), so both of these need to persist between updateConfig calls - deriving them from the
+  // keys present in a single update would reset minDist based on an incomplete picture.
+  private var hasCustomActivationCriteria = false
+  private var hasExplicitMinDist = false
   private var activeOffsetXStart = MIN_VALUE_IGNORE
   private var activeOffsetXEnd = MAX_VALUE_IGNORE
   private var failOffsetXStart = MAX_VALUE_IGNORE
@@ -90,6 +96,8 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
     minVelocityY = DEFAULT_MIN_VELOCITY_Y
     minVelocity = DEFAULT_MIN_VELOCITY
     minDist = defaultMinDist
+    hasCustomActivationCriteria = false
+    hasExplicitMinDist = false
     minPointers = DEFAULT_MIN_POINTERS
     maxPointers = DEFAULT_MAX_POINTERS
     activateAfterLongPress = DEFAULT_ACTIVATE_AFTER_LONG_PRESS
@@ -270,15 +278,14 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
 
     override fun updateConfig(handler: PanGestureHandler, config: ReadableMap) {
       super.updateConfig(handler, config)
-      var hasCustomActivationCriteria = false
       if (config.hasKey(KEY_ACTIVE_OFFSET_X_START)) {
         handler.activeOffsetXStart =
           PixelUtil.toPixelFromDIP(
             config.getDouble(
               KEY_ACTIVE_OFFSET_X_START,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_ACTIVE_OFFSET_X_END)) {
         handler.activeOffsetXEnd =
@@ -287,7 +294,7 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_ACTIVE_OFFSET_X_END,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_FAIL_OFFSET_RANGE_X_START)) {
         handler.failOffsetXStart =
@@ -296,7 +303,7 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_FAIL_OFFSET_RANGE_X_START,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_FAIL_OFFSET_RANGE_X_END)) {
         handler.failOffsetXEnd =
@@ -305,7 +312,7 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_FAIL_OFFSET_RANGE_X_END,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_ACTIVE_OFFSET_Y_START)) {
         handler.activeOffsetYStart =
@@ -314,7 +321,7 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_ACTIVE_OFFSET_Y_START,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_ACTIVE_OFFSET_Y_END)) {
         handler.activeOffsetYEnd =
@@ -323,7 +330,7 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_ACTIVE_OFFSET_Y_END,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_FAIL_OFFSET_RANGE_Y_START)) {
         handler.failOffsetYStart =
@@ -332,7 +339,7 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_FAIL_OFFSET_RANGE_Y_START,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_FAIL_OFFSET_RANGE_Y_END)) {
         handler.failOffsetYEnd =
@@ -341,28 +348,30 @@ class PanGestureHandler(context: Context?) : GestureHandler() {
               KEY_FAIL_OFFSET_RANGE_Y_END,
             ),
           )
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_MIN_VELOCITY)) {
         // This value is actually in DPs/ms, but we can use the same function as for converting
         // from DPs to pixels as the unit we're converting is in the numerator
         handler.minVelocity = PixelUtil.toPixelFromDIP(config.getDouble(KEY_MIN_VELOCITY))
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_MIN_VELOCITY_X)) {
         handler.minVelocityX = PixelUtil.toPixelFromDIP(config.getDouble(KEY_MIN_VELOCITY_X))
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
       if (config.hasKey(KEY_MIN_VELOCITY_Y)) {
         handler.minVelocityY = PixelUtil.toPixelFromDIP(config.getDouble(KEY_MIN_VELOCITY_Y))
-        hasCustomActivationCriteria = true
+        handler.hasCustomActivationCriteria = true
       }
 
       // PanGestureHandler sets minDist by default, if there are custom criteria specified we want
-      // to reset that setting and use provided criteria instead.
+      // to reset that setting and use provided criteria instead - unless minDist was explicitly
+      // configured, in which case it must survive partial config updates of other criteria.
       if (config.hasKey(KEY_MIN_DIST)) {
         handler.minDist = PixelUtil.toPixelFromDIP(config.getDouble(KEY_MIN_DIST))
-      } else if (hasCustomActivationCriteria) {
+        handler.hasExplicitMinDist = true
+      } else if (handler.hasCustomActivationCriteria && !handler.hasExplicitMinDist) {
         handler.minDist = Float.MAX_VALUE
       }
       if (config.hasKey(KEY_MIN_POINTERS)) {
