Simplify logic of TapGestureRecognizer (flutter#30227)

dkwingsmt · web-flow · commit fbefd6b816a8 · 2019-04-01T10:58:30.000-07:00
Refactors the logic of TapGestureRecognizer, making the calling dependency unidirectional between resolve(accept) and checkUp.
diff --git a/packages/flutter/lib/src/gestures/tap.dart b/packages/flutter/lib/src/gestures/tap.dart
@@ -172,7 +172,10 @@ class TapGestureRecognizer extends PrimaryPointerGestureRecognizer {
   void handlePrimaryPointer(PointerEvent event) {
     if (event is PointerUpEvent) {
       _finalPosition = event.position;
-      _checkUp();
+      if (_wonArenaForPrimaryPointer) {
+        resolve(GestureDisposition.accepted);
+        _checkUp();
+      }
     } else if (event is PointerCancelEvent) {
       if (_sentTapDown && onTapCancel != null) {
         invokeCallback<void>('onTapCancel', onTapCancel);
@@ -230,16 +233,7 @@ class TapGestureRecognizer extends PrimaryPointerGestureRecognizer {
   }
 
   void _checkUp() {
-    if (_wonArenaForPrimaryPointer && _finalPosition != null) {
-      resolve(GestureDisposition.accepted);
-      if (!_wonArenaForPrimaryPointer || _finalPosition == null) {
-        // It is possible that resolve has just recursively called _checkUp
-        // (see https://github.com/flutter/flutter/issues/12470).
-        // In that case _wonArenaForPrimaryPointer will be false (as _checkUp
-        // calls _reset) and we return here to avoid double invocation of the
-        // tap callbacks.
-        return;
-      }
+    if (_finalPosition != null) {
       if (onTapUp != null)
         invokeCallback<void>('onTapUp', () { onTapUp(TapUpDetails(globalPosition: _finalPosition)); });
       if (onTap != null)
