Add buttons to gestures (#30339)

* Callbacks of tap, long press, drag, and double tap GR respond to only primary events.
* Add "secondary" callbacks to tap.
* Recognizers only compete on events if there are any related callbacks.
* Add "kSecondaryButton" constant.

packages/flutter/lib/src/gestures/events.dart

@@ -8,22 +8,35 @@ import 'package:flutter/foundation.dart';
 
 export 'dart:ui' show Offset, PointerDeviceKind;
 
-/// The bit of [PointerEvent.buttons] that corresponds to the "primary
-/// action" on any device.
+/// The bit of [PointerEvent.buttons] that corresponds to a cross-device
+/// behavior of "primary operation".
 ///
-/// More specifially,
+/// More specifially, it includes:
 ///
-///  * For touch screen, it's when the pointer contacts the screen.
-///  * For stylus and inverted stylus, it's when the pen contacts the screen.
-///  * For mouse, it's when the primary button is pressed.
+///  * [kTouchContact]: The pointer contacts the touch screen.
+///  * [kStylusContact]: The stylus contacts the screen.
+///  * [kPrimaryMouseButton]: The primary mouse button.
 ///
 /// See also:
 ///
-///  * [kTouchContact]: an alias of this constant when used by touch screen.
-///  * [kStylusContact]: an alias of this constant when used by stylus.
-///  * [kPrimaryMouseButton]: an alias of this constant when used by mouse.
+///  * [kSecondaryButton], which describes a cross-device behavior of
+///    "secondary operation".
 const int kPrimaryButton = 0x01;
 
+/// The bit of [PointerEvent.buttons] that corresponds to a cross-device
+/// behavior of "secondary operation".
+///
+/// It is equivalent to:
+///
+///  * [kPrimaryStylusButton]: The stylus contacts the screen.
+///  * [kSecondaryMouseButton]: The primary mouse button.
+///
+/// See also:
+///
+///  * [kPrimaryButton], which describes a cross-device behavior of
+///    "primary operation".
+const int kSecondaryButton = 0x02;
+
 /// The bit of [PointerEvent.buttons] that corresponds to the primary mouse button.
 ///
 /// The primary mouse button is typically the left button on the top of the
@@ -31,28 +44,40 @@ const int kPrimaryButton = 0x01;
 ///
 /// See also:
 ///
-///  * [kTouchContact]: an alias of this constant when used by touch screen.
+///  * [kPrimaryButton], which has the same value but describes its cross-device
+///    concept.
 const int kPrimaryMouseButton = kPrimaryButton;
 
 /// The bit of [PointerEvent.buttons] that corresponds to the secondary mouse button.
 ///
 /// The secondary mouse button is typically the right button on the top of the
 /// mouse but can be reconfigured to be a different physical button.
-const int kSecondaryMouseButton = 0x02;
+///
+/// See also:
+///
+///  * [kSecondaryButton], which has the same value but describes its cross-device
+///    concept.
+const int kSecondaryMouseButton = kSecondaryButton;
 
 /// The bit of [PointerEvent.buttons] that corresponds to when a stylus
 /// contacting the screen.
 ///
 /// See also:
 ///
-///  * [kPrimaryButton]: an alias of this constant for any device.
+///  * [kPrimaryButton], which has the same value but describes its cross-device
+///    concept.
 const int kStylusContact = kPrimaryButton;
 
 /// The bit of [PointerEvent.buttons] that corresponds to the primary stylus button.
 ///
 /// The primary stylus button is typically the top of the stylus and near the
 /// tip but can be reconfigured to be a different physical button.
-const int kPrimaryStylusButton = 0x02;
+///
+/// See also:
+///
+///  * [kSecondaryButton], which has the same value but describes its cross-device
+///    concept.
+const int kPrimaryStylusButton = kSecondaryButton;
 
 /// The bit of [PointerEvent.buttons] that corresponds to the middle mouse button.
 ///
@@ -84,7 +109,8 @@ const int kForwardMouseButton = 0x10;
 ///
 /// See also:
 ///
-///  * [kPrimaryButton]: an alias of this constant for any device.
+///  * [kPrimaryButton], which has the same value but describes its cross-device
+///    concept.
 const int kTouchContact = kPrimaryButton;
 
 /// The bit of [PointerEvent.buttons] that corresponds to the nth mouse button.
@@ -104,6 +130,47 @@ int nthMouseButton(int number) => (kPrimaryMouseButton << (number - 1)) & kMaxUn
 /// for some stylus buttons.
 int nthStylusButton(int number) => (kPrimaryStylusButton << (number - 1)) & kMaxUnsignedSMI;
 
+/// Returns the button of `buttons` with the smallest integer.
+///
+/// The `buttons` parameter is a bitfield where each set bit represents a button.
+/// This function returns the set bit closest to the least significant bit.
+///
+/// It returns zero when `buttons` is zero.
+///
+/// Example:
+///
+/// ```dart
+///   assert(rightmostButton(0x1) == 0x1);
+///   assert(rightmostButton(0x11) == 0x1);
+///   assert(rightmostButton(0) == 0);
+/// ```
+///
+/// See also:
+///
+///   * [isSingleButton], which checks if a `buttons` contains exactly one button.
+int smallestButton(int buttons) => buttons & (-buttons);
+
+/// Returns whether `buttons` contains one and only one button.
+///
+/// The `buttons` parameter is a bitfield where each set bit represents a button.
+/// This function returns whether there is only one set bit in the given integer.
+///
+/// It returns false when `buttons` is zero.
+///
+/// Example:
+///
+/// ```dart
+///   assert(isSingleButton(0x1) == true);
+///   assert(isSingleButton(0x11) == false);
+///   assert(isSingleButton(0) == false);
+/// ```
+///
+/// See also:
+///
+///   * [smallestButton], which returns the button in a `buttons` bitfield with
+///     the smallest integer button.
+bool isSingleButton(int buttons) => buttons != 0 && (smallestButton(buttons) == buttons);
+
 /// Base class for touch, stylus, or mouse events.
 ///
 /// Pointer events operate in the coordinate space of the screen, scaled to

packages/flutter/lib/src/gestures/long_press.dart

@@ -109,6 +109,10 @@ class LongPressEndDetails {
 /// until it's recognized. Once the gesture is accepted, the finger can be
 /// moved, triggering [onLongPressMoveUpdate] callbacks, unless the
 /// [postAcceptSlopTolerance] constructor argument is specified.
+///
+/// [LongPressGestureRecognizer] competes on pointer events of [kPrimaryButton]
+/// only when it has at least one non-null callback. If it has no callbacks, it
+/// is a no-op.
 class LongPressGestureRecognizer extends PrimaryPointerGestureRecognizer {
   /// Creates a long-press gesture recognizer.
   ///
@@ -133,89 +137,159 @@ class LongPressGestureRecognizer extends PrimaryPointerGestureRecognizer {
   );
 
   bool _longPressAccepted = false;
-
   Offset _longPressOrigin;
+  // The buttons sent by `PointerDownEvent`. If a `PointerMoveEvent` comes with a
+  // different set of buttons, the gesture is canceled.
+  int _initialButtons;
 
-  /// Called when a long press gesture has been recognized.
+  /// Called when a long press gesture by a primary button has been recognized.
   ///
   /// See also:
   ///
+  ///  * [kPrimaryButton], the button this callback responds to.
   ///  * [onLongPressStart], which has the same timing but has data for the
   ///    press location.
   GestureLongPressCallback onLongPress;
 
-  /// Callback for long press start with gesture location.
+  /// Called when a long press gesture by a primary button has been recognized.
   ///
   /// See also:
   ///
-  ///  * [onLongPress], which has the same timing but without the location data.
+  ///  * [kPrimaryButton], the button this callback responds to.
+  ///  * [onLongPress], which has the same timing but without details.
+  ///  * [LongPressStartDetails], which is passed as an argument to this callback.
   GestureLongPressStartCallback onLongPressStart;
 
-  /// Callback for moving the gesture after the lang press is recognized.
+  /// Called when moving after the long press by a primary button is recognized.
+  ///
+  /// See also:
+  ///
+  ///  * [kPrimaryButton], the button this callback responds to.
+  ///  * [LongPressMoveUpdateDetails], which is passed as an argument to this
+  ///    callback.
   GestureLongPressMoveUpdateCallback onLongPressMoveUpdate;
 
-  /// Called when the pointer stops contacting the screen after the long-press.
+  /// Called when the pointer stops contacting the screen after a long-press
+  /// by a primary button.
   ///
   /// See also:
   ///
+  ///  * [kPrimaryButton], the button this callback responds to.
   ///  * [onLongPressEnd], which has the same timing but has data for the up
   ///    gesture location.
   GestureLongPressUpCallback onLongPressUp;
 
-  /// Callback for long press end with gesture location.
+  /// Called when the pointer stops contacting the screen after a long-press
+  /// by a primary button.
   ///
   /// See also:
   ///
-  ///  * [onLongPressUp], which has the same timing but without the location data.
+  ///  * [kPrimaryButton], the button this callback responds to.
+  ///  * [onLongPressUp], which has the same timing, but without details.
+  ///  * [LongPressEndDetails], which is passed as an argument to this
+  ///    callback.
   GestureLongPressEndCallback onLongPressEnd;
 
+  @override
+  bool isPointerAllowed(PointerDownEvent event) {
+    switch (event.buttons) {
+      case kPrimaryButton:
+        if (onLongPressStart == null &&
+            onLongPress == null &&
+            onLongPressMoveUpdate == null &&
+            onLongPressEnd == null &&
+            onLongPressUp == null)
+          return false;
+        break;
+      default:
+        return false;
+    }
+    return super.isPointerAllowed(event);
+  }
+
   @override
   void didExceedDeadline() {
+    // Exceeding the deadline puts the gesture in the accepted state.
     resolve(GestureDisposition.accepted);
     _longPressAccepted = true;
     super.acceptGesture(primaryPointer);
-    if (onLongPress != null) {
-      invokeCallback<void>('onLongPress', onLongPress);
-    }
-    if (onLongPressStart != null) {
-      invokeCallback<void>('onLongPressStart', () {
-        onLongPressStart(LongPressStartDetails(
-          globalPosition: _longPressOrigin,
-        ));
-      });
-    }
+    _checkLongPressStart();
   }
 
   @override
   void handlePrimaryPointer(PointerEvent event) {
     if (event is PointerUpEvent) {
       if (_longPressAccepted == true) {
-        if (onLongPressUp != null) {
-          invokeCallback<void>('onLongPressUp', onLongPressUp);
-        }
-        if (onLongPressEnd != null) {
-          invokeCallback<void>('onLongPressEnd', () {
-            onLongPressEnd(LongPressEndDetails(
-              globalPosition: event.position,
-            ));
-          });
-        }
-        _longPressAccepted = false;
+        _checkLongPressEnd(event);
       } else {
+        // Pointer is lifted before timeout.
         resolve(GestureDisposition.rejected);
       }
-    } else if (event is PointerDownEvent || event is PointerCancelEvent) {
+      _reset();
+    } else if (event is PointerCancelEvent) {
+      _reset();
+    } else if (event is PointerDownEvent) {
       // The first touch.
-      _longPressAccepted = false;
       _longPressOrigin = event.position;
-    } else if (event is PointerMoveEvent && _longPressAccepted && onLongPressMoveUpdate != null) {
-      invokeCallback<void>('onLongPressMoveUpdate', () {
-        onLongPressMoveUpdate(LongPressMoveUpdateDetails(
-          globalPosition: event.position,
-          offsetFromOrigin: event.position - _longPressOrigin,
-        ));
-      });
+      _initialButtons = event.buttons;
+    } else if (event is PointerMoveEvent) {
+      if (event.buttons != _initialButtons) {
+        resolve(GestureDisposition.rejected);
+        stopTrackingPointer(primaryPointer);
+      } else if (_longPressAccepted) {
+        _checkLongPressMoveUpdate(event);
+      }
+    }
+  }
+
+  void _checkLongPressStart() {
+    assert(_initialButtons == kPrimaryButton);
+    final LongPressStartDetails details = LongPressStartDetails(
+      globalPosition: _longPressOrigin,
+    );
+    if (onLongPressStart != null)
+      invokeCallback<void>('onLongPressStart',
+        () => onLongPressStart(details));
+    if (onLongPress != null)
+      invokeCallback<void>('onLongPress', onLongPress);
+  }
+
+  void _checkLongPressMoveUpdate(PointerEvent event) {
+    assert(_initialButtons == kPrimaryButton);
+    final LongPressMoveUpdateDetails details = LongPressMoveUpdateDetails(
+      globalPosition: event.position,
+      offsetFromOrigin: event.position - _longPressOrigin,
+    );
+    if (onLongPressMoveUpdate != null)
+      invokeCallback<void>('onLongPressMoveUpdate',
+        () => onLongPressMoveUpdate(details));
+  }
+
+  void _checkLongPressEnd(PointerEvent event) {
+    assert(_initialButtons == kPrimaryButton);
+    final LongPressEndDetails details = LongPressEndDetails(
+      globalPosition: event.position,
+    );
+    if (onLongPressEnd != null)
+      invokeCallback<void>('onLongPressEnd', () => onLongPressEnd(details));
+    if (onLongPressUp != null)
+      invokeCallback<void>('onLongPressUp', onLongPressUp);
+  }
+
+  void _reset() {
+    _longPressAccepted = false;
+    _longPressOrigin = null;
+    _initialButtons = null;
+  }
+
+  @override
+  void resolve(GestureDisposition disposition) {
+    if (_longPressAccepted && disposition == GestureDisposition.rejected) {
+      // This can happen if the gesture has been canceled. For example when
+      // the buttons have changed.
+      _reset();
     }
+    super.resolve(disposition);
   }
 
   @override

packages/flutter/lib/src/gestures/multitap.dart

@@ -16,6 +16,10 @@ import 'tap.dart';
 
 /// Signature for callback when the user has tapped the screen at the same
 /// location twice in quick succession.
+///
+/// See also:
+///
+///  * [GestureDetector.onDoubleTap], which matches this signature.
 typedef GestureDoubleTapCallback = void Function();
 
 /// Signature used by [MultiTapGestureRecognizer] for when a pointer that might
@@ -60,13 +64,16 @@ class _TapTracker {
     @required Duration doubleTapMinTime,
   }) : assert(doubleTapMinTime != null),
        assert(event != null),
+       assert(event.buttons != null),
        pointer = event.pointer,
        _initialPosition = event.position,
+       initialButtons = event.buttons,
        _doubleTapMinTimeCountdown = _CountdownZoned(duration: doubleTapMinTime);
 
   final int pointer;
   final GestureArenaEntry entry;
   final Offset _initialPosition;
+  final int initialButtons;
   final _CountdownZoned _doubleTapMinTimeCountdown;
 
   bool _isTrackingPointer = false;
@@ -93,10 +100,18 @@ class _TapTracker {
   bool hasElapsedMinTime() {
     return _doubleTapMinTimeCountdown.timeout;
   }
+
+  bool hasSameButton(PointerDownEvent event) {
+    return event.buttons == initialButtons;
+  }
 }
 
 /// Recognizes when the user has tapped the screen at the same location twice in
 /// quick succession.
+///
+/// [DoubleTapGestureRecognizer] competes on pointer events of [kPrimaryButton]
+/// only when it has a non-null callback. If it has no callbacks, it is a no-op.
+///
 class DoubleTapGestureRecognizer extends GestureRecognizer {
   /// Create a gesture recognizer for double taps.
   ///
@@ -126,26 +141,53 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
   // - The long timer between taps expires
   // - The gesture arena decides we have been rejected wholesale
 
-  /// Called when the user has tapped the screen at the same location twice in
-  /// quick succession.
+  /// Called when the user has tapped the screen with a primary button at the
+  /// same location twice in quick succession.
+  ///
+  /// This triggers when the pointer stops contacting the device after the 2nd tap,
+  /// immediately after [onDoubleTapUp].
+  ///
+  /// See also:
+  ///
+  ///  * [kPrimaryButton], the button this callback responds to.
   GestureDoubleTapCallback onDoubleTap;
 
   Timer _doubleTapTimer;
   _TapTracker _firstTap;
   final Map<int, _TapTracker> _trackers = <int, _TapTracker>{};
 
+  @override
+  bool isPointerAllowed(PointerEvent event) {
+    if (_firstTap == null) {
+      switch (event.buttons) {
+        case kPrimaryButton:
+          if (onDoubleTap == null)
+            return false;
+          break;
+        default:
+          return false;
+      }
+    }
+    return super.isPointerAllowed(event);
+  }
+
   @override
   void addAllowedPointer(PointerEvent event) {
     if (_firstTap != null) {
       if (!_firstTap.isWithinTolerance(event, kDoubleTapSlop)) {
         // Ignore out-of-bounds second taps.
         return;
-      } else if (!_firstTap.hasElapsedMinTime()) {
-        // Restart when the second tap is too close to the first.
+      } else if (!_firstTap.hasElapsedMinTime() || !_firstTap.hasSameButton(event)) {
+        // Restart when the second tap is too close to the first, or when buttons
+        // mismatch.
         _reset();
-        return addAllowedPointer(event);
+        return _trackFirstTap(event);
       }
     }
+    _trackFirstTap(event);
+  }
+
+  void _trackFirstTap(PointerEvent event) {
     _stopDoubleTapTimer();
     final _TapTracker tracker = _TapTracker(
       event: event,
@@ -235,8 +277,7 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
     tracker.entry.resolve(GestureDisposition.accepted);
     _freezeTracker(tracker);
     _trackers.remove(tracker.pointer);
-    if (onDoubleTap != null)
-      invokeCallback<void>('onDoubleTap', onDoubleTap);
+    _checkUp(tracker.initialButtons);
     _reset();
   }
 
@@ -260,6 +301,12 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
     }
   }
 
+  void _checkUp(int buttons) {
+    assert(buttons == kPrimaryButton);
+    if (onDoubleTap != null)
+      invokeCallback<void>('onDoubleTap', onDoubleTap);
+  }
+
   @override
   String get debugDescription => 'double tap';
 }

packages/flutter/test/gestures/debug_test.dart

@@ -147,7 +147,8 @@ void main() {
   });
 
   test('TapGestureRecognizer _sentTapDown toString', () {
-    final TapGestureRecognizer tap = TapGestureRecognizer();
+    final TapGestureRecognizer tap = TapGestureRecognizer()
+      ..onTap = () {}; // Add a callback so that event can be added
     expect(tap.toString(), equalsIgnoringHashCodes('TapGestureRecognizer#00000(state: ready)'));
     const PointerEvent event = PointerDownEvent(pointer: 1, position: Offset(10.0, 10.0));
     tap.addPointer(event);

packages/flutter/test/gestures/double_tap_test.dart

@@ -75,7 +75,7 @@ void main() {
     position: Offset(25.0, 25.0),
   );
 
-  // Down/up pair 5: normal tap sequence identical to pair 1 with different pointer
+  // Down/up pair 5: normal tap sequence identical to pair 1
   const PointerDownEvent down5 = PointerDownEvent(
     pointer: 5,
     position: Offset(10.0, 10.0),
@@ -86,6 +86,18 @@ void main() {
     position: Offset(11.0, 9.0),
   );
 
+  // Down/up pair 6: normal tap sequence close to pair 1 but on secondary button
+  const PointerDownEvent down6 = PointerDownEvent(
+    pointer: 6,
+    position: Offset(10.0, 10.0),
+    buttons: kSecondaryMouseButton,
+  );
+
+  const PointerUpEvent up6 = PointerUpEvent(
+    pointer: 6,
+    position: Offset(11.0, 9.0),
+  );
+
   testGesture('Should recognize double tap', (GestureTester tester) {
     final DoubleTapGestureRecognizer tap = DoubleTapGestureRecognizer();
 
@@ -606,4 +618,183 @@ void main() {
 
     tap.dispose();
   });
+
+  group('Enforce consistent-button restriction:', () {
+    testGesture('Button change should interrupt existing sequence', (GestureTester tester) {
+      // Down1 -> down6 (different button from 1) -> down2 (same button as 1)
+      // Down1 and down2 could've been a double tap, but is interrupted by down 6.
+
+      const Duration interval = Duration(milliseconds: 100);
+      assert(interval * 2 < kDoubleTapTimeout);
+      assert(interval > kDoubleTapMinTime);
+
+      final DoubleTapGestureRecognizer tap = DoubleTapGestureRecognizer();
+
+      bool doubleTapRecognized = false;
+      tap.onDoubleTap = () {
+        doubleTapRecognized = true;
+      };
+
+      tap.addPointer(down1);
+      tester.closeArena(1);
+      tester.route(down1);
+      tester.route(up1);
+      GestureBinding.instance.gestureArena.sweep(1);
+
+      tester.async.elapse(interval);
+
+      tap.addPointer(down6);
+      tester.closeArena(6);
+      tester.route(down6);
+      tester.route(up6);
+      GestureBinding.instance.gestureArena.sweep(6);
+
+      tester.async.elapse(interval);
+      expect(doubleTapRecognized, isFalse);
+
+      tap.addPointer(down2);
+      tester.closeArena(2);
+      tester.route(down2);
+      tester.route(up2);
+      GestureBinding.instance.gestureArena.sweep(2);
+
+      expect(doubleTapRecognized, isFalse);
+
+      tap.dispose();
+    });
+
+    testGesture('Button change should start a valid sequence', (GestureTester tester) {
+      // Down6 -> down1 (different button from 6) -> down2 (same button as 1)
+
+      const Duration interval = Duration(milliseconds: 100);
+      assert(interval * 2 < kDoubleTapTimeout);
+      assert(interval > kDoubleTapMinTime);
+
+      final DoubleTapGestureRecognizer tap = DoubleTapGestureRecognizer();
+
+      bool doubleTapRecognized = false;
+      tap.onDoubleTap = () {
+        doubleTapRecognized = true;
+      };
+
+      tap.addPointer(down6);
+      tester.closeArena(6);
+      tester.route(down6);
+      tester.route(up6);
+      GestureBinding.instance.gestureArena.sweep(6);
+
+      tester.async.elapse(interval);
+
+      tap.addPointer(down1);
+      tester.closeArena(1);
+      tester.route(down1);
+      tester.route(up1);
+      GestureBinding.instance.gestureArena.sweep(1);
+
+      expect(doubleTapRecognized, isFalse);
+      tester.async.elapse(interval);
+
+      tap.addPointer(down2);
+      tester.closeArena(2);
+      tester.route(down2);
+      tester.route(up2);
+      GestureBinding.instance.gestureArena.sweep(2);
+
+      expect(doubleTapRecognized, isTrue);
+
+      tap.dispose();
+    });
+  });
+
+  group('Recognizers listening on different buttons do not form competition:', () {
+    // This test is assisted by tap recognizers. If a tap gesture has
+    // no competing recognizers, a pointer down event triggers its onTapDown
+    // immediately; if there are competitors, onTapDown is triggered after a
+    // timeout.
+    // The following tests make sure that double tap recognizers do not form
+    // competition with a tap gesture recognizer listening on a different button.
+
+    final List<String> recognized = <String>[];
+    TapGestureRecognizer tapPrimary;
+    TapGestureRecognizer tapSecondary;
+    DoubleTapGestureRecognizer doubleTap;
+    setUp(() {
+      tapPrimary = TapGestureRecognizer()
+        ..onTapDown = (TapDownDetails details) {
+          recognized.add('tapPrimary');
+        };
+      tapSecondary = TapGestureRecognizer()
+        ..onSecondaryTapDown = (TapDownDetails details) {
+          recognized.add('tapSecondary');
+        };
+      doubleTap = DoubleTapGestureRecognizer()
+        ..onDoubleTap = () {
+          recognized.add('doubleTap');
+        };
+    });
+
+    tearDown(() {
+      recognized.clear();
+      tapPrimary.dispose();
+      tapSecondary.dispose();
+      doubleTap.dispose();
+    });
+
+    testGesture('A primary double tap recognizer does not form competion with a secondary tap recognizer', (GestureTester tester) {
+      doubleTap.addPointer(down6);
+      tapSecondary.addPointer(down6);
+      tester.closeArena(down6.pointer);
+
+      tester.route(down6);
+      expect(recognized, <String>['tapSecondary']);
+    });
+
+    testGesture('A primary double tap recognizer forms competion with a primary tap recognizer', (GestureTester tester) {
+      doubleTap.addPointer(down1);
+      tapPrimary.addPointer(down1);
+      tester.closeArena(down1.pointer);
+
+      tester.route(down1);
+      expect(recognized, <String>[]);
+
+      tester.async.elapse(const Duration(milliseconds: 300));
+      expect(recognized, <String>['tapPrimary']);
+    });
+  });
+
+  testGesture('A secondary double tap should not trigger primary', (GestureTester tester) {
+    final List<String> recognized = <String>[];
+    final DoubleTapGestureRecognizer doubleTap = DoubleTapGestureRecognizer()
+      ..onDoubleTap = () {
+        recognized.add('primary');
+      };
+
+    // Down/up pair 7: normal tap sequence close to pair 6
+    const PointerDownEvent down7 = PointerDownEvent(
+      pointer: 7,
+      position: Offset(10.0, 10.0),
+      buttons: kSecondaryMouseButton,
+    );
+
+    const PointerUpEvent up7 = PointerUpEvent(
+      pointer: 7,
+      position: Offset(11.0, 9.0),
+    );
+
+    doubleTap.addPointer(down6);
+    tester.closeArena(6);
+    tester.route(down6);
+    tester.route(up6);
+    GestureBinding.instance.gestureArena.sweep(6);
+
+    tester.async.elapse(const Duration(milliseconds: 100));
+    doubleTap.addPointer(down7);
+    tester.closeArena(7);
+    tester.route(down7);
+    tester.route(up7);
+    expect(recognized, <String>[]);
+
+    recognized.clear();
+    doubleTap.dispose();
+  });
 }

packages/flutter/test/gestures/events_test.dart

@@ -20,6 +20,20 @@ void main() {
     expect(nthStylusButton(2), kSecondaryStylusButton);
   });
 
+  testGesture('smallestButton tests', (GestureTester tester) {
+    expect(smallestButton(0x0), equals(0x0));
+    expect(smallestButton(0x1), equals(0x1));
+    expect(smallestButton(0x200), equals(0x200));
+    expect(smallestButton(0x220), equals(0x20));
+  });
+
+  testGesture('isSingleButton tests', (GestureTester tester) {
+    expect(isSingleButton(0x0), isFalse);
+    expect(isSingleButton(0x1), isTrue);
+    expect(isSingleButton(0x200), isTrue);
+    expect(isSingleButton(0x220), isFalse);
+  });
+
   group('Default values of PointerEvents:', () {
     // Some parameters are intentionally set to a non-trivial value.
 

packages/flutter/test/gestures/long_press_test.dart

@@ -7,6 +7,7 @@ import 'package:flutter/gestures.dart';
 import '../flutter_test_alternative.dart';
 import 'gesture_tester.dart';
 
+// Down/move/up pair 1: normal tap sequence
 const PointerDownEvent down = PointerDownEvent(
   pointer: 5,
   position: Offset(10, 10),
@@ -22,6 +23,29 @@ const PointerMoveEvent move = PointerMoveEvent(
   position: Offset(100, 200),
 );
 
+// Down/up pair 2: normal tap sequence far away from pair 1
+const PointerDownEvent down2 = PointerDownEvent(
+  pointer: 6,
+  position: Offset(10, 10),
+);
+
+const PointerUpEvent up2 = PointerUpEvent(
+  pointer: 6,
+  position: Offset(11, 9),
+);
+
+// Down/up pair 3: tap sequence with secondary button
+const PointerDownEvent down3 = PointerDownEvent(
+  pointer: 7,
+  position: Offset(30, 30),
+  buttons: kSecondaryButton,
+);
+
+const PointerUpEvent up3 = PointerUpEvent(
+  pointer: 7,
+  position: Offset(31, 29),
+);
+
 void main() {
   setUp(ensureGestureBinding);
 
@@ -187,6 +211,48 @@ void main() {
 
       longPress.dispose();
     });
+
+    testGesture('Should not recognize long press with more than one buttons', (GestureTester tester) {
+      longPress.addPointer(const PointerDownEvent(
+        pointer: 5,
+        kind: PointerDeviceKind.mouse,
+        buttons: kSecondaryMouseButton | kMiddleMouseButton,
+        position: Offset(10, 10),
+      ));
+      tester.closeArena(5);
+      expect(longPressDown, isFalse);
+      tester.route(down);
+      expect(longPressDown, isFalse);
+      tester.async.elapse(const Duration(milliseconds: 1000));
+      expect(longPressDown, isFalse);
+      tester.route(up);
+      expect(longPressUp, isFalse);
+
+      longPress.dispose();
+    });
+
+    testGesture('Should cancel long press when buttons change before acceptance', (GestureTester tester) {
+      longPress.addPointer(down);
+      tester.closeArena(5);
+      expect(longPressDown, isFalse);
+      tester.route(down);
+      expect(longPressDown, isFalse);
+      tester.async.elapse(const Duration(milliseconds: 300));
+      expect(longPressDown, isFalse);
+      tester.route(const PointerMoveEvent(
+        pointer: 5,
+        kind: PointerDeviceKind.mouse,
+        buttons: kMiddleMouseButton,
+        position: Offset(10, 10),
+      ));
+      expect(longPressDown, isFalse);
+      tester.async.elapse(const Duration(milliseconds: 700));
+      expect(longPressDown, isFalse);
+      tester.route(up);
+      expect(longPressUp, isFalse);
+
+      longPress.dispose();
+    });
   });
 
   group('long press drag', () {
@@ -279,6 +345,107 @@ void main() {
     });
   });
 
+  group('Enforce consistent-button restriction:', () {
+    // In sequence between `down` and `up` but with buttons changed
+    const PointerMoveEvent moveR = PointerMoveEvent(
+      pointer: 5,
+      buttons: kSecondaryButton,
+      position: Offset(10, 10),
+    );
+
+    final List<String> recognized = <String>[];
+
+    LongPressGestureRecognizer longPress;
+
+    setUp(() {
+      longPress = LongPressGestureRecognizer()
+        ..onLongPressStart = (LongPressStartDetails details) {
+          recognized.add('start');
+        }
+        ..onLongPressEnd = (LongPressEndDetails details) {
+          recognized.add('end');
+        };
+    });
+
+    tearDown(() {
+      longPress.dispose();
+      recognized.clear();
+    });
+
+    testGesture('Should cancel long press when buttons change before acceptance', (GestureTester tester) {
+      // First press
+      longPress.addPointer(down);
+      tester.closeArena(down.pointer);
+      tester.route(down);
+      tester.async.elapse(const Duration(milliseconds: 300));
+      tester.route(moveR);
+      expect(recognized, <String>[]);
+      tester.async.elapse(const Duration(milliseconds: 700));
+      tester.route(up);
+      expect(recognized, <String>[]);
+    });
+
+    testGesture('Buttons change before acceptance should not prevent the next long press', (GestureTester tester) {
+      // First press
+      longPress.addPointer(down);
+      tester.closeArena(down.pointer);
+      tester.route(down);
+      tester.async.elapse(const Duration(milliseconds: 300));
+      tester.route(moveR);
+      tester.async.elapse(const Duration(milliseconds: 700));
+      tester.route(up);
+      recognized.clear();
+
+      // Second press
+      longPress.addPointer(down2);
+      tester.closeArena(down2.pointer);
+      tester.route(down2);
+      tester.async.elapse(const Duration(milliseconds: 1000));
+      expect(recognized, <String>['start']);
+      recognized.clear();
+
+      tester.route(up2);
+      expect(recognized, <String>['end']);
+    });
+
+    testGesture('Should cancel long press when buttons change after acceptance', (GestureTester tester) {
+      // First press
+      longPress.addPointer(down);
+      tester.closeArena(down.pointer);
+      tester.route(down);
+      tester.async.elapse(const Duration(milliseconds: 1000));
+      expect(recognized, <String>['start']);
+      recognized.clear();
+
+      tester.route(moveR);
+      expect(recognized, <String>[]);
+      tester.route(up);
+      expect(recognized, <String>[]);
+    });
+
+    testGesture('Buttons change after acceptance should not prevent the next long press', (GestureTester tester) {
+      // First press
+      longPress.addPointer(down);
+      tester.closeArena(down.pointer);
+      tester.route(down);
+      tester.async.elapse(const Duration(milliseconds: 1000));
+      tester.route(moveR);
+      tester.route(up);
+      recognized.clear();
+
+      // Second press
+      longPress.addPointer(down2);
+      tester.closeArena(down2.pointer);
+      tester.route(down2);
+      tester.async.elapse(const Duration(milliseconds: 1000));
+      expect(recognized, <String>['start']);
+      recognized.clear();
+
+      tester.route(up2);
+      expect(recognized, <String>['end']);
+    });
+  });
+
   testGesture('Can filter long press based on device kind', (GestureTester tester) {
     final LongPressGestureRecognizer mouseLongPress = LongPressGestureRecognizer(kind: PointerDeviceKind.mouse);
 
@@ -318,4 +485,107 @@ void main() {
 
     mouseLongPress.dispose();
   });
+
+  group('Recognizers listening on different buttons do not form competition:', () {
+    // This test is assisted by tap recognizers. If a tap gesture has
+    // no competing recognizers, a pointer down event triggers its onTapDown
+    // immediately; if there are competitors, onTapDown is triggered after a
+    // timeout.
+    // The following tests make sure that long press recognizers do not form
+    // competition with a tap gesture recognizer listening on a different button.
+
+    final List<String> recognized = <String>[];
+    TapGestureRecognizer tapPrimary;
+    TapGestureRecognizer tapSecondary;
+    LongPressGestureRecognizer longPress;
+    setUp(() {
+      tapPrimary = TapGestureRecognizer()
+        ..onTapDown = (TapDownDetails details) {
+          recognized.add('tapPrimary');
+        };
+      tapSecondary = TapGestureRecognizer()
+        ..onSecondaryTapDown = (TapDownDetails details) {
+          recognized.add('tapSecondary');
+        };
+      longPress = LongPressGestureRecognizer()
+        ..onLongPressStart = (_) {
+          recognized.add('longPress');
+        };
+    });
+
+    tearDown(() {
+      recognized.clear();
+      tapPrimary.dispose();
+      tapSecondary.dispose();
+      longPress.dispose();
+    });
+
+    testGesture('A primary long press recognizer does not form competion with a secondary tap recognizer', (GestureTester tester) {
+      longPress.addPointer(down3);
+      tapSecondary.addPointer(down3);
+      tester.closeArena(down3.pointer);
+
+      tester.route(down3);
+      expect(recognized, <String>['tapSecondary']);
+    });
+
+    testGesture('A primary long press recognizer forms competion with a primary tap recognizer', (GestureTester tester) {
+      longPress.addPointer(down);
+      tapPrimary.addPointer(down);
+      tester.closeArena(down.pointer);
+
+      tester.route(down);
+      expect(recognized, <String>[]);
+
+      tester.route(up);
+      expect(recognized, <String>['tapPrimary']);
+    });
+  });
+
+  testGesture('A secondary long press should not trigger primary', (GestureTester tester) {
+    final List<String> recognized = <String>[];
+    final LongPressGestureRecognizer longPress = LongPressGestureRecognizer()
+      ..onLongPressStart = (LongPressStartDetails details) {
+        recognized.add('primaryStart');
+      }
+      ..onLongPress = () {
+        recognized.add('primary');
+      }
+      ..onLongPressMoveUpdate = (LongPressMoveUpdateDetails details) {
+        recognized.add('primaryUpdate');
+      }
+      ..onLongPressEnd = (LongPressEndDetails details) {
+        recognized.add('primaryEnd');
+      }
+      ..onLongPressUp = () {
+        recognized.add('primaryUp');
+      };
+
+    const PointerDownEvent down2 = PointerDownEvent(
+      pointer: 2,
+      buttons: kSecondaryButton,
+      position: Offset(30.0, 30.0),
+    );
+
+    const PointerMoveEvent move2 = PointerMoveEvent(
+      pointer: 2,
+      buttons: kSecondaryButton,
+      position: Offset(100, 200),
+    );
+
+    const PointerUpEvent up2 = PointerUpEvent(
+      pointer: 2,
+      position: Offset(100, 201),
+    );
+
+    longPress.addPointer(down2);
+    tester.closeArena(2);
+    tester.route(down2);
+    tester.async.elapse(const Duration(milliseconds: 700));
+    tester.route(move2);
+    tester.route(up2);
+    expect(recognized, <String>[]);
+    longPress.dispose();
+    recognized.clear();
+  });
 }

packages/flutter/test/widgets/platform_view_test.dart

@@ -592,7 +592,10 @@ void main() {
                 viewType: 'webview',
                 gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
                   Factory<VerticalDragGestureRecognizer>(
-                        () => VerticalDragGestureRecognizer(),
+                    () {
+                      return VerticalDragGestureRecognizer()
+                        ..onStart = (_) {}; // Add callback to enable recognizer
+                    },
                   ),
                 },
                 layoutDirection: TextDirection.ltr,
@@ -1263,7 +1266,10 @@ void main() {
                 viewType: 'webview',
                 gestureRecognizers: <Factory<OneSequenceGestureRecognizer>>{
                   Factory<VerticalDragGestureRecognizer>(
-                        () => VerticalDragGestureRecognizer(),
+                    () {
+                      return VerticalDragGestureRecognizer()
+                        ..onStart = (_) {}; // Add callback to enable recognizer
+                    },
                   ),
                 },
                 layoutDirection: TextDirection.ltr,

packages/flutter_test/lib/src/test_pointer.dart

@@ -22,9 +22,14 @@ class TestPointer {
   ///
   /// Multiple [TestPointer]s created with the same pointer identifier will
   /// interfere with each other if they are used in parallel.
-  TestPointer([this.pointer = 1, this.kind = PointerDeviceKind.touch])
+  TestPointer([
+    this.pointer = 1,
+    this.kind = PointerDeviceKind.touch,
+    this.buttons = kPrimaryButton,
+  ])
       : assert(kind != null),
-        assert(pointer != null);
+        assert(pointer != null),
+        assert(buttons != null);
 
   /// The pointer identifier used for events generated by this object.
   ///
@@ -35,6 +40,10 @@ class TestPointer {
   /// [PointerDeviceKind.touch].
   final PointerDeviceKind kind;
 
+  /// The kind of buttons to simulate on Down and Move events. Defaults to
+  /// [kPrimaryButton].
+  int buttons;
+
   /// Whether the pointer simulated by this object is currently down.
   ///
   /// A pointer is released (goes up) by calling [up] or [cancel].
@@ -81,6 +90,7 @@ class TestPointer {
       kind: kind,
       pointer: pointer,
       position: location,
+      buttons: buttons,
     );
   }
 
@@ -105,6 +115,7 @@ class TestPointer {
       pointer: pointer,
       position: newLocation,
       delta: delta,
+      buttons: buttons,
     );
   }