Alexander Marek
1 day ago
committed by
GitHub
GitHub
10 changed files with 420 additions and 83 deletions
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using System; |
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using Avalonia.Controls.Primitives; |
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using Avalonia.Input; |
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using Avalonia.Input.GestureRecognizers; |
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namespace Avalonia.Controls.PullToRefresh |
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{ |
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internal class ScrollablePullGestureRecognizer : GestureRecognizer |
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{ |
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private int _gestureId; |
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private bool _pullInProgress; |
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private double _delta = 1; |
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private Point _initialPosition; |
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private IPointer? _tracking; |
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/// <summary>
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/// Defines the <see cref="PullDirection"/> property.
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/// </summary>
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public static readonly StyledProperty<PullDirection> PullDirectionProperty = |
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AvaloniaProperty.Register<ScrollablePullGestureRecognizer, PullDirection>(nameof(PullDirection)); |
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public PullDirection PullDirection |
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{ |
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get => GetValue(PullDirectionProperty); |
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set => SetValue(PullDirectionProperty, value); |
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} |
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public bool IsMouseEnabled { get; set; } |
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public ScrollablePullGestureRecognizer(PullDirection pullDirection, bool IsMouseEnabled) |
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{ |
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PullDirection = pullDirection; |
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IsMouseEnabled = IsMouseEnabled; |
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} |
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public ScrollablePullGestureRecognizer() { } |
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protected override void PointerCaptureLost(IPointer pointer) |
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{ |
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if (_tracking == pointer) |
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{ |
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EndPull(); |
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} |
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} |
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protected override void PointerPressed(PointerPressedEventArgs e) |
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{ |
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var isEnabledOnPlatform = (e.Pointer.Type == PointerType.Touch || e.Pointer.Type == PointerType.Pen) // either it is a touch device
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|| IsMouseEnabled; // or desktop is enabled
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if (Target != null && Target is Visual visual && isEnabledOnPlatform) |
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{ |
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_tracking = e.Pointer; |
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_initialPosition = e.GetPosition(visual); |
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} |
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} |
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protected override void PointerMoved(PointerEventArgs e) |
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{ |
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if (_tracking != e.Pointer) |
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return; |
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if (Target is Visual visual && visual is IScrollable scrollable && CanPull(scrollable)) |
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{ |
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var currentPosition = e.GetPosition(visual); |
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var delta = CalculateDelta(currentPosition); |
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bool pulling = delta.Y > 0 || delta.X > 0; |
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_pullInProgress = (_pullInProgress, pulling) switch |
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{ |
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(false, false) => false, |
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(false, true) => BeginPull(e, delta), |
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(true, true) => HandlePull(e, delta), |
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(true, false) => EndPull(), |
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}; |
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} |
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} |
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protected override void PointerReleased(PointerReleasedEventArgs e) |
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{ |
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if (_pullInProgress == true) |
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{ |
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EndPull(); |
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e.Pointer.Capture(null); |
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} |
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_tracking = null; |
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_initialPosition = default; |
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_pullInProgress = false; |
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} |
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private bool BeginPull(PointerEventArgs e, Vector delta) |
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{ |
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_gestureId = PullGestureEventArgs.GetNextFreeId(); |
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return HandlePull(e, delta); |
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} |
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private bool HandlePull(PointerEventArgs e, Vector delta) |
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{ |
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Capture(e.Pointer); |
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var pullEventArgs = new PullGestureEventArgs(_gestureId, delta, PullDirection); |
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Target?.RaiseEvent(pullEventArgs); |
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e.Handled = pullEventArgs.Handled; |
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return true; |
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} |
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private bool EndPull() |
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{ |
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Target?.RaiseEvent(new PullGestureEndedEventArgs(_gestureId, PullDirection)); |
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return false; |
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} |
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private Vector CalculateDelta(Point currentPosition) => PullDirection switch |
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{ |
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PullDirection.TopToBottom => new Vector(0, currentPosition.Y - _initialPosition.Y), |
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PullDirection.BottomToTop => new Vector(0, _initialPosition.Y - currentPosition.Y), |
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PullDirection.LeftToRight => new Vector(currentPosition.X - _initialPosition.X, 0), |
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PullDirection.RightToLeft => new Vector(_initialPosition.X - currentPosition.X, 0), |
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_ => default, |
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}; |
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private bool CanPull(IScrollable scrollable) => PullDirection switch |
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{ |
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PullDirection.TopToBottom => scrollable.Offset.Y < _delta, |
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PullDirection.BottomToTop => Math.Abs(scrollable.Offset.Y + scrollable.Viewport.Height - scrollable.Extent.Height) <= _delta, |
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PullDirection.LeftToRight => scrollable.Offset.X < _delta, |
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PullDirection.RightToLeft => Math.Abs(scrollable.Offset.X + scrollable.Viewport.Width - scrollable.Extent.Width) <= _delta, |
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_ => false, |
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}; |
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} |
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} |
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