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Unverified Commit 52b5b3ea authored by Todd Volkert's avatar Todd Volkert Committed by GitHub
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Add GestureDetector.onDoubleTapDown() (#64431) 

* Add GestureDetector.onDoubleTapDown()

* Review comments
parent 8b52e6a8
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Showing with 211 additions and 306 deletions
packages/flutter/lib/src/gestures/multitap.dart
View file @ 52b5b3ea
......@@ -2,7 +2,6 @@
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:async';
import 'dart:ui' show Offset;
import 'package:vector_math/vector_math_64.dart';
......@@ -60,7 +59,7 @@ class _CountdownZoned {
class _TapTracker {
_TapTracker({
required PointerDownEvent event,
this.entry,
required this.entry,
required Duration doubleTapMinTime,
}) : assert(doubleTapMinTime != null),
assert(event != null),
......@@ -71,7 +70,7 @@ class _TapTracker {
_doubleTapMinTimeCountdown = _CountdownZoned(duration: doubleTapMinTime);
final int pointer;
final GestureArenaEntry? entry;
final GestureArenaEntry entry;
final Offset _initialGlobalPosition;
final int initialButtons;
final _CountdownZoned _doubleTapMinTimeCountdown;
......@@ -122,25 +121,45 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
}) : super(debugOwner: debugOwner, kind: kind);
// Implementation notes:
//
// The double tap recognizer can be in one of four states. There's no
// explicit enum for the states, because they are already captured by
// the state of existing fields. Specifically:
// Waiting on first tap: In this state, the _trackers list is empty, and
//
// 1. Waiting on first tap: In this state, the _trackers list is empty, and
// _firstTap is null.
// First tap in progress: In this state, the _trackers list contains all
// 2. First tap in progress: In this state, the _trackers list contains all
// the states for taps that have begun but not completed. This list can
// have more than one entry if two pointers begin to tap.
// Waiting on second tap: In this state, one of the in-progress taps has
// 3. Waiting on second tap: In this state, one of the in-progress taps has
// completed successfully. The _trackers list is again empty, and
// _firstTap records the successful tap.
// Second tap in progress: Much like the "first tap in progress" state, but
// 4. Second tap in progress: Much like the "first tap in progress" state, but
// _firstTap is non-null. If a tap completes successfully while in this
// state, the callback is called and the state is reset.
//
// There are various other scenarios that cause the state to reset:
//
// - All in-progress taps are rejected (by time, distance, pointercancel, etc)
// - The long timer between taps expires
// - The gesture arena decides we have been rejected wholesale
/// A pointer has contacted the screen with a primary button at the same
/// location twice in quick succession, which might be the start of a double
/// tap.
///
/// This triggers immediately after the down event of the second tap.
///
/// If this recognizer doesn't win the arena, [onDoubleTapCancel] is called
/// next. Otherwise, [onDoubleTap] is called next.
///
/// See also:
///
/// * [kPrimaryButton], the button this callback responds to.
/// * [TapDownDetails], which is passed as an argument to this callback.
/// * [GestureDetector.onDoubleTapDown], which exposes this callback.
GestureTapDownCallback? onDoubleTapDown;
/// Called when the user has tapped the screen with a primary button at the
/// same location twice in quick succession.
///
......@@ -150,47 +169,71 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
/// See also:
///
/// * [kPrimaryButton], the button this callback responds to.
/// * [GestureDetector.onDoubleTap], which exposes this callback.
GestureDoubleTapCallback? onDoubleTap;
/// A pointer that previously triggered [onDoubleTapDown] will not end up
/// causing a double tap.
///
/// This triggers once the gesture loses the arena if [onDoubleTapDown] has
/// previously been triggered.
///
/// If this recognizer wins the arena, [onDoubleTap] is called instead.
///
/// See also:
///
/// * [kPrimaryButton], the button this callback responds to.
/// * [GestureDetector.onDoubleTapCancel], which exposes this callback.
GestureTapCancelCallback? onDoubleTapCancel;
Timer? _doubleTapTimer;
_TapTracker? _firstTap;
final Map<int, _TapTracker> _trackers = <int, _TapTracker>{};
@override
bool isPointerAllowed(PointerEvent event) {
bool isPointerAllowed(PointerDownEvent event) {
if (_firstTap == null) {
switch (event.buttons) {
case kPrimaryButton:
if (onDoubleTap == null)
if (onDoubleTapDown == null &&
onDoubleTap == null &&
onDoubleTapCancel == null)
return false;
break;
default:
return false;
}
}
return super.isPointerAllowed(event as PointerDownEvent);
return super.isPointerAllowed(event);
}
@override
void addAllowedPointer(PointerEvent event) {
void addAllowedPointer(PointerDownEvent event) {
if (_firstTap != null) {
if (!_firstTap!.isWithinGlobalTolerance(event, kDoubleTapSlop)) {
// Ignore out-of-bounds second taps.
return;
} else if (!_firstTap!.hasElapsedMinTime() || !_firstTap!.hasSameButton(event as PointerDownEvent)) {
// Restart when the second tap is too close to the first, or when buttons
// mismatch.
} else if (!_firstTap!.hasElapsedMinTime() || !_firstTap!.hasSameButton(event)) {
// Restart when the second tap is too close to the first (touch screens
// often detect touches intermittently), or when buttons mismatch.
_reset();
return _trackFirstTap(event);
return _trackTap(event);
} else if (onDoubleTapDown != null) {
final TapDownDetails details = TapDownDetails(
globalPosition: event.position,
localPosition: event.localPosition,
kind: getKindForPointer(event.pointer),
);
invokeCallback<void>('onDoubleTapDown', () => onDoubleTapDown!(details));
}
}
_trackFirstTap(event);
_trackTap(event);
}
void _trackFirstTap(PointerEvent event) {
void _trackTap(PointerDownEvent event) {
_stopDoubleTapTimer();
final _TapTracker tracker = _TapTracker(
event: event as PointerDownEvent,
event: event,
entry: GestureBinding.instance!.gestureArena.add(event.pointer, this),
doubleTapMinTime: kDoubleTapMinTime,
);
......@@ -231,15 +274,18 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
void _reject(_TapTracker tracker) {
_trackers.remove(tracker.pointer);
tracker.entry!.resolve(GestureDisposition.rejected);
tracker.entry.resolve(GestureDisposition.rejected);
_freezeTracker(tracker);
// If the first tap is in progress, and we've run out of taps to track,
// reset won't have any work to do. But if we're in the second tap, we need
// to clear intermediate state.
if (_firstTap != null &&
(_trackers.isEmpty || tracker == _firstTap))
if (_firstTap != null) {
if (tracker == _firstTap) {
_reset();
} else {
_checkCancel();
if (_trackers.isEmpty)
_reset();
}
}
}
@override
void dispose() {
......@@ -250,6 +296,8 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
void _reset() {
_stopDoubleTapTimer();
if (_firstTap != null) {
if (_trackers.isNotEmpty)
_checkCancel();
// Note, order is important below in order for the resolve -> reject logic
// to work properly.
final _TapTracker tracker = _firstTap!;
......@@ -272,8 +320,8 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
}
void _registerSecondTap(_TapTracker tracker) {
_firstTap!.entry!.resolve(GestureDisposition.accepted);
tracker.entry!.resolve(GestureDisposition.accepted);
_firstTap!.entry.resolve(GestureDisposition.accepted);
tracker.entry.resolve(GestureDisposition.accepted);
_freezeTracker(tracker);
_trackers.remove(tracker.pointer);
_checkUp(tracker.initialButtons);
......@@ -306,6 +354,11 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
invokeCallback<void>('onDoubleTap', onDoubleTap!);
}
void _checkCancel() {
if (onDoubleTapCancel != null)
invokeCallback<void>('onDoubleTapCancel', onDoubleTapCancel!);
}
@override
String get debugDescription => 'double tap';
}
......@@ -381,7 +434,7 @@ class _TapGesture extends _TapTracker {
if (_wonArena)
reject();
else
entry!.resolve(GestureDisposition.rejected); // eventually calls reject()
entry.resolve(GestureDisposition.rejected); // eventually calls reject()
}
void _check() {
......
packages/flutter/lib/src/widgets/gesture_detector.dart
View file @ 52b5b3ea
......@@ -229,7 +229,9 @@ class GestureDetector extends StatelessWidget {
this.onTertiaryTapDown,
this.onTertiaryTapUp,
this.onTertiaryTapCancel,
this.onDoubleTapDown,
this.onDoubleTap,
this.onDoubleTapCancel,
this.onLongPress,
this.onLongPressStart,
this.onLongPressMoveUpdate,
......@@ -428,6 +430,20 @@ class GestureDetector extends StatelessWidget {
/// * [kTertiaryButton], the button this callback responds to.
final GestureTapCancelCallback onTertiaryTapCancel;
/// A pointer that might cause a double tap has contacted the screen at a
/// particular location.
///
/// Triggered immediately after the down event of the second tap.
///
/// If the user completes the double tap and the gesture wins, [onDoubleTap]
/// will be called after this callback. Otherwise, [onDoubleTapCancel] will
/// be called after this callback.
///
/// See also:
///
/// * [kPrimaryButton], the button this callback responds to.
final GestureTapDownCallback onDoubleTapDown;
/// The user has tapped the screen with a primary button at the same location
/// twice in quick succession.
///
......@@ -436,6 +452,14 @@ class GestureDetector extends StatelessWidget {
/// * [kPrimaryButton], the button this callback responds to.
final GestureTapCallback onDoubleTap;
/// The pointer that previously triggered [onDoubleTapDown] will not end up
/// causing a double tap.
///
/// See also:
///
/// * [kPrimaryButton], the button this callback responds to.
final GestureTapCancelCallback onDoubleTapCancel;
/// Called when a long press gesture with a primary button has been recognized.
///
/// Triggered when a pointer has remained in contact with the screen at the
......@@ -774,7 +798,10 @@ class GestureDetector extends StatelessWidget {
gestures[DoubleTapGestureRecognizer] = GestureRecognizerFactoryWithHandlers<DoubleTapGestureRecognizer>(
() => DoubleTapGestureRecognizer(debugOwner: this),
(DoubleTapGestureRecognizer instance) {
instance.onDoubleTap = onDoubleTap;
instance
..onDoubleTapDown = onDoubleTapDown
..onDoubleTap = onDoubleTap
..onDoubleTapCancel = onDoubleTapCancel;
},
);
}
......
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