A cross-platform UI framework for .NET
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using System;
using System.Collections.Generic;
using System.Linq;
using Avalonia.Controls;
using Avalonia.Controls.Metadata;
using Avalonia.Data;
using Avalonia.Input.GestureRecognizers;
using Avalonia.Input.TextInput;
using Avalonia.Interactivity;
using Avalonia.VisualTree;
#nullable enable
namespace Avalonia.Input
{
/// <summary>
/// Implements input-related functionality for a control.
/// </summary>
[PseudoClasses(":disabled", ":focus", ":focus-visible", ":focus-within", ":pointerover")]
public class InputElement : Interactive, IInputElement
{
/// <summary>
/// Defines the <see cref="Focusable"/> property.
/// </summary>
public static readonly StyledProperty<bool> FocusableProperty =
AvaloniaProperty.Register<InputElement, bool>(nameof(Focusable));
/// <summary>
/// Defines the <see cref="IsEnabled"/> property.
/// </summary>
public static readonly StyledProperty<bool> IsEnabledProperty =
AvaloniaProperty.Register<InputElement, bool>(nameof(IsEnabled), true);
/// <summary>
/// Defines the <see cref="IsEffectivelyEnabled"/> property.
/// </summary>
public static readonly DirectProperty<InputElement, bool> IsEffectivelyEnabledProperty =
AvaloniaProperty.RegisterDirect<InputElement, bool>(
nameof(IsEffectivelyEnabled),
o => o.IsEffectivelyEnabled);
/// <summary>
/// Gets or sets associated mouse cursor.
/// </summary>
public static readonly StyledProperty<Cursor?> CursorProperty =
AvaloniaProperty.Register<InputElement, Cursor?>(nameof(Cursor), null, true);
/// <summary>
/// Defines the <see cref="IsKeyboardFocusWithin"/> property.
/// </summary>
public static readonly DirectProperty<InputElement, bool> IsKeyboardFocusWithinProperty =
AvaloniaProperty.RegisterDirect<InputElement, bool>(
nameof(IsKeyboardFocusWithin),
o => o.IsKeyboardFocusWithin);
/// <summary>
/// Defines the <see cref="IsFocused"/> property.
/// </summary>
public static readonly DirectProperty<InputElement, bool> IsFocusedProperty =
AvaloniaProperty.RegisterDirect<InputElement, bool>(nameof(IsFocused), o => o.IsFocused);
/// <summary>
/// Defines the <see cref="IsHitTestVisible"/> property.
/// </summary>
public static readonly StyledProperty<bool> IsHitTestVisibleProperty =
AvaloniaProperty.Register<InputElement, bool>(nameof(IsHitTestVisible), true);
/// <summary>
/// Defines the <see cref="IsPointerOver"/> property.
/// </summary>
public static readonly DirectProperty<InputElement, bool> IsPointerOverProperty =
AvaloniaProperty.RegisterDirect<InputElement, bool>(nameof(IsPointerOver), o => o.IsPointerOver);
/// <summary>
/// Defines the <see cref="IsTabStop"/> property.
/// </summary>
public static readonly StyledProperty<bool> IsTabStopProperty =
KeyboardNavigation.IsTabStopProperty.AddOwner<InputElement>();
/// <summary>
/// Defines the <see cref="GotFocus"/> event.
/// </summary>
public static readonly RoutedEvent<GotFocusEventArgs> GotFocusEvent =
RoutedEvent.Register<InputElement, GotFocusEventArgs>(nameof(GotFocus), RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="LostFocus"/> event.
/// </summary>
public static readonly RoutedEvent<RoutedEventArgs> LostFocusEvent =
RoutedEvent.Register<InputElement, RoutedEventArgs>(nameof(LostFocus), RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="KeyDown"/> event.
/// </summary>
public static readonly RoutedEvent<KeyEventArgs> KeyDownEvent =
RoutedEvent.Register<InputElement, KeyEventArgs>(
nameof(KeyDown),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="KeyUp"/> event.
/// </summary>
public static readonly RoutedEvent<KeyEventArgs> KeyUpEvent =
RoutedEvent.Register<InputElement, KeyEventArgs>(
nameof(KeyUp),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="TabIndex"/> property.
/// </summary>
public static readonly StyledProperty<int> TabIndexProperty =
KeyboardNavigation.TabIndexProperty.AddOwner<InputElement>();
/// <summary>
/// Defines the <see cref="TextInput"/> event.
/// </summary>
public static readonly RoutedEvent<TextInputEventArgs> TextInputEvent =
RoutedEvent.Register<InputElement, TextInputEventArgs>(
nameof(TextInput),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="TextInputMethodClientRequested"/> event.
/// </summary>
public static readonly RoutedEvent<TextInputMethodClientRequestedEventArgs> TextInputMethodClientRequestedEvent =
RoutedEvent.Register<InputElement, TextInputMethodClientRequestedEventArgs>(
nameof(TextInputMethodClientRequested),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="PointerEnter"/> event.
/// </summary>
public static readonly RoutedEvent<PointerEventArgs> PointerEnterEvent =
RoutedEvent.Register<InputElement, PointerEventArgs>(nameof(PointerEnter), RoutingStrategies.Direct);
/// <summary>
/// Defines the <see cref="PointerLeave"/> event.
/// </summary>
public static readonly RoutedEvent<PointerEventArgs> PointerLeaveEvent =
RoutedEvent.Register<InputElement, PointerEventArgs>(nameof(PointerLeave), RoutingStrategies.Direct);
/// <summary>
/// Defines the <see cref="PointerMoved"/> event.
/// </summary>
public static readonly RoutedEvent<PointerEventArgs> PointerMovedEvent =
RoutedEvent.Register<InputElement, PointerEventArgs>(
nameof(PointerMoved),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="PointerPressed"/> event.
/// </summary>
public static readonly RoutedEvent<PointerPressedEventArgs> PointerPressedEvent =
RoutedEvent.Register<InputElement, PointerPressedEventArgs>(
nameof(PointerPressed),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="PointerReleased"/> event.
/// </summary>
public static readonly RoutedEvent<PointerReleasedEventArgs> PointerReleasedEvent =
RoutedEvent.Register<InputElement, PointerReleasedEventArgs>(
nameof(PointerReleased),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="PointerCaptureLost"/> routed event.
/// </summary>
public static readonly RoutedEvent<PointerCaptureLostEventArgs> PointerCaptureLostEvent =
RoutedEvent.Register<InputElement, PointerCaptureLostEventArgs>(
nameof(PointerCaptureLost),
RoutingStrategies.Direct);
/// <summary>
/// Defines the <see cref="PointerWheelChanged"/> event.
/// </summary>
public static readonly RoutedEvent<PointerWheelEventArgs> PointerWheelChangedEvent =
RoutedEvent.Register<InputElement, PointerWheelEventArgs>(
nameof(PointerWheelChanged),
RoutingStrategies.Tunnel | RoutingStrategies.Bubble);
/// <summary>
/// Defines the <see cref="Tapped"/> event.
/// </summary>
public static readonly RoutedEvent<TappedEventArgs> TappedEvent = Gestures.TappedEvent;
/// <summary>
/// Defines the <see cref="DoubleTapped"/> event.
/// </summary>
public static readonly RoutedEvent<TappedEventArgs> DoubleTappedEvent = Gestures.DoubleTappedEvent;
private bool _isEffectivelyEnabled = true;
private bool _isFocused;
private bool _isKeyboardFocusWithin;
private bool _isFocusVisible;
private bool _isPointerOver;
private GestureRecognizerCollection? _gestureRecognizers;
/// <summary>
/// Initializes static members of the <see cref="InputElement"/> class.
/// </summary>
static InputElement()
{
IsEnabledProperty.Changed.Subscribe(IsEnabledChanged);
GotFocusEvent.AddClassHandler<InputElement>((x, e) => x.OnGotFocus(e));
LostFocusEvent.AddClassHandler<InputElement>((x, e) => x.OnLostFocus(e));
KeyDownEvent.AddClassHandler<InputElement>((x, e) => x.OnKeyDown(e));
KeyUpEvent.AddClassHandler<InputElement>((x, e) => x.OnKeyUp(e));
TextInputEvent.AddClassHandler<InputElement>((x, e) => x.OnTextInput(e));
PointerEnterEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerEnterCore(e));
PointerLeaveEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerLeaveCore(e));
PointerMovedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerMoved(e));
PointerPressedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerPressed(e));
PointerReleasedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerReleased(e));
PointerCaptureLostEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerCaptureLost(e));
PointerWheelChangedEvent.AddClassHandler<InputElement>((x, e) => x.OnPointerWheelChanged(e));
}
public InputElement()
{
UpdatePseudoClasses(IsFocused, IsPointerOver);
}
/// <summary>
/// Occurs when the control receives focus.
/// </summary>
public event EventHandler<GotFocusEventArgs>? GotFocus
{
add { AddHandler(GotFocusEvent, value); }
remove { RemoveHandler(GotFocusEvent, value); }
}
/// <summary>
/// Occurs when the control loses focus.
/// </summary>
public event EventHandler<RoutedEventArgs>? LostFocus
{
add { AddHandler(LostFocusEvent, value); }
remove { RemoveHandler(LostFocusEvent, value); }
}
/// <summary>
/// Occurs when a key is pressed while the control has focus.
/// </summary>
public event EventHandler<KeyEventArgs>? KeyDown
{
add { AddHandler(KeyDownEvent, value); }
remove { RemoveHandler(KeyDownEvent, value); }
}
/// <summary>
/// Occurs when a key is released while the control has focus.
/// </summary>
public event EventHandler<KeyEventArgs>? KeyUp
{
add { AddHandler(KeyUpEvent, value); }
remove { RemoveHandler(KeyUpEvent, value); }
}
/// <summary>
/// Occurs when a user typed some text while the control has focus.
/// </summary>
public event EventHandler<TextInputEventArgs>? TextInput
{
add { AddHandler(TextInputEvent, value); }
remove { RemoveHandler(TextInputEvent, value); }
}
/// <summary>
/// Occurs when an input element gains input focus and input method is looking for the corresponding client
/// </summary>
public event EventHandler<TextInputMethodClientRequestedEventArgs>? TextInputMethodClientRequested
{
add { AddHandler(TextInputMethodClientRequestedEvent, value); }
remove { RemoveHandler(TextInputMethodClientRequestedEvent, value); }
}
/// <summary>
/// Occurs when the pointer enters the control.
/// </summary>
public event EventHandler<PointerEventArgs>? PointerEnter
{
add { AddHandler(PointerEnterEvent, value); }
remove { RemoveHandler(PointerEnterEvent, value); }
}
/// <summary>
/// Occurs when the pointer leaves the control.
/// </summary>
public event EventHandler<PointerEventArgs>? PointerLeave
{
add { AddHandler(PointerLeaveEvent, value); }
remove { RemoveHandler(PointerLeaveEvent, value); }
}
/// <summary>
/// Occurs when the pointer moves over the control.
/// </summary>
public event EventHandler<PointerEventArgs>? PointerMoved
{
add { AddHandler(PointerMovedEvent, value); }
remove { RemoveHandler(PointerMovedEvent, value); }
}
/// <summary>
/// Occurs when the pointer is pressed over the control.
/// </summary>
public event EventHandler<PointerPressedEventArgs>? PointerPressed
{
add { AddHandler(PointerPressedEvent, value); }
remove { RemoveHandler(PointerPressedEvent, value); }
}
/// <summary>
/// Occurs when the pointer is released over the control.
/// </summary>
public event EventHandler<PointerReleasedEventArgs>? PointerReleased
{
add { AddHandler(PointerReleasedEvent, value); }
remove { RemoveHandler(PointerReleasedEvent, value); }
}
/// <summary>
/// Occurs when the control or its child control loses the pointer capture for any reason,
/// event will not be triggered for a parent control if capture was transferred to another child of that parent control
/// </summary>
public event EventHandler<PointerCaptureLostEventArgs>? PointerCaptureLost
{
add => AddHandler(PointerCaptureLostEvent, value);
remove => RemoveHandler(PointerCaptureLostEvent, value);
}
/// <summary>
/// Occurs when the mouse is scrolled over the control.
/// </summary>
public event EventHandler<PointerWheelEventArgs>? PointerWheelChanged
{
add { AddHandler(PointerWheelChangedEvent, value); }
remove { RemoveHandler(PointerWheelChangedEvent, value); }
}
/// <summary>
/// Occurs when a tap gesture occurs on the control.
/// </summary>
public event EventHandler<TappedEventArgs>? Tapped
{
add { AddHandler(TappedEvent, value); }
remove { RemoveHandler(TappedEvent, value); }
}
/// <summary>
/// Occurs when a double-tap gesture occurs on the control.
/// </summary>
public event EventHandler<TappedEventArgs>? DoubleTapped
{
add { AddHandler(DoubleTappedEvent, value); }
remove { RemoveHandler(DoubleTappedEvent, value); }
}
/// <summary>
/// Gets or sets a value indicating whether the control can receive focus.
/// </summary>
public bool Focusable
{
get { return GetValue(FocusableProperty); }
set { SetValue(FocusableProperty, value); }
}
/// <summary>
/// Gets or sets a value indicating whether the control is enabled for user interaction.
/// </summary>
public bool IsEnabled
{
get { return GetValue(IsEnabledProperty); }
set { SetValue(IsEnabledProperty, value); }
}
/// <summary>
/// Gets or sets associated mouse cursor.
/// </summary>
public Cursor? Cursor
{
get { return GetValue(CursorProperty); }
set { SetValue(CursorProperty, value); }
}
/// <summary>
/// Gets a value indicating whether keyboard focus is anywhere within the element or its visual tree child elements.
/// </summary>
public bool IsKeyboardFocusWithin
{
get => _isKeyboardFocusWithin;
internal set => SetAndRaise(IsKeyboardFocusWithinProperty, ref _isKeyboardFocusWithin, value);
}
/// <summary>
/// Gets a value indicating whether the control is focused.
/// </summary>
public bool IsFocused
{
get { return _isFocused; }
private set { SetAndRaise(IsFocusedProperty, ref _isFocused, value); }
}
/// <summary>
/// Gets or sets a value indicating whether the control is considered for hit testing.
/// </summary>
public bool IsHitTestVisible
{
get { return GetValue(IsHitTestVisibleProperty); }
set { SetValue(IsHitTestVisibleProperty, value); }
}
/// <summary>
/// Gets a value indicating whether the pointer is currently over the control.
/// </summary>
public bool IsPointerOver
{
get { return _isPointerOver; }
internal set { SetAndRaise(IsPointerOverProperty, ref _isPointerOver, value); }
}
/// <summary>
/// Gets or sets a value that indicates whether the control is included in tab navigation.
/// </summary>
public bool IsTabStop
{
get => GetValue(IsTabStopProperty);
set => SetValue(IsTabStopProperty, value);
}
/// <inheritdoc/>
public bool IsEffectivelyEnabled
{
get => _isEffectivelyEnabled;
private set
{
SetAndRaise(IsEffectivelyEnabledProperty, ref _isEffectivelyEnabled, value);
PseudoClasses.Set(":disabled", !value);
}
}
/// <summary>
/// Gets or sets a value that determines the order in which elements receive focus when the
/// user navigates through controls by pressing the Tab key.
/// </summary>
public int TabIndex
{
get => GetValue(TabIndexProperty);
set => SetValue(TabIndexProperty, value);
}
public List<KeyBinding> KeyBindings { get; } = new List<KeyBinding>();
/// <summary>
/// Allows a derived class to override the enabled state of the control.
/// </summary>
/// <remarks>
/// Derived controls may wish to disable the enabled state of the control without overwriting the
/// user-supplied <see cref="IsEnabled"/> setting. This can be done by overriding this property
/// to return the overridden enabled state. If the value returned from <see cref="IsEnabledCore"/>
/// should change, then the derived control should call <see cref="UpdateIsEffectivelyEnabled()"/>.
/// </remarks>
protected virtual bool IsEnabledCore => IsEnabled;
public GestureRecognizerCollection GestureRecognizers
=> _gestureRecognizers ?? (_gestureRecognizers = new GestureRecognizerCollection(this));
/// <summary>
/// Focuses the control.
/// </summary>
public void Focus()
{
FocusManager.Instance?.Focus(this);
}
/// <inheritdoc/>
protected override void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs e)
{
base.OnDetachedFromVisualTreeCore(e);
if (IsFocused)
{
FocusManager.Instance?.Focus(null);
}
}
/// <inheritdoc/>
protected override void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
{
base.OnAttachedToVisualTreeCore(e);
UpdateIsEffectivelyEnabled();
}
/// <summary>
/// Called before the <see cref="GotFocus"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnGotFocus(GotFocusEventArgs e)
{
var isFocused = e.Source == this;
_isFocusVisible = isFocused && (e.NavigationMethod == NavigationMethod.Directional || e.NavigationMethod == NavigationMethod.Tab);
IsFocused = isFocused;
}
/// <summary>
/// Called before the <see cref="LostFocus"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnLostFocus(RoutedEventArgs e)
{
_isFocusVisible = false;
IsFocused = false;
}
/// <summary>
/// Called before the <see cref="KeyDown"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnKeyDown(KeyEventArgs e)
{
}
/// <summary>
/// Called before the <see cref="KeyUp"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnKeyUp(KeyEventArgs e)
{
}
/// <summary>
/// Called before the <see cref="TextInput"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnTextInput(TextInputEventArgs e)
{
}
/// <summary>
/// Called before the <see cref="PointerEnter"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerEnter(PointerEventArgs e)
{
}
/// <summary>
/// Called before the <see cref="PointerLeave"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerLeave(PointerEventArgs e)
{
}
/// <summary>
/// Called before the <see cref="PointerMoved"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerMoved(PointerEventArgs e)
{
if (_gestureRecognizers?.HandlePointerMoved(e) == true)
e.Handled = true;
}
/// <summary>
/// Called before the <see cref="PointerPressed"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerPressed(PointerPressedEventArgs e)
{
if (_gestureRecognizers?.HandlePointerPressed(e) == true)
e.Handled = true;
}
/// <summary>
/// Called before the <see cref="PointerReleased"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerReleased(PointerReleasedEventArgs e)
{
if (_gestureRecognizers?.HandlePointerReleased(e) == true)
e.Handled = true;
}
/// <summary>
/// Called before the <see cref="PointerCaptureLost"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerCaptureLost(PointerCaptureLostEventArgs e)
{
_gestureRecognizers?.HandlePointerCaptureLost(e);
}
/// <summary>
/// Called before the <see cref="PointerWheelChanged"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
protected virtual void OnPointerWheelChanged(PointerWheelEventArgs e)
{
}
protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
{
base.OnPropertyChanged(change);
if (change.Property == IsFocusedProperty)
{
UpdatePseudoClasses(change.GetNewValue<bool>(), null);
}
else if (change.Property == IsPointerOverProperty)
{
UpdatePseudoClasses(null, change.GetNewValue<bool>());
}
else if (change.Property == IsKeyboardFocusWithinProperty)
{
PseudoClasses.Set(":focus-within", change.GetNewValue<bool>());
}
}
/// <summary>
/// Updates the <see cref="IsEffectivelyEnabled"/> property value according to the parent
/// control's enabled state and <see cref="IsEnabledCore"/>.
/// </summary>
protected void UpdateIsEffectivelyEnabled()
{
UpdateIsEffectivelyEnabled(this.GetVisualParent<InputElement>());
}
private static void IsEnabledChanged(AvaloniaPropertyChangedEventArgs e)
{
((InputElement)e.Sender).UpdateIsEffectivelyEnabled();
}
/// <summary>
/// Called before the <see cref="PointerEnter"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
private void OnPointerEnterCore(PointerEventArgs e)
{
IsPointerOver = true;
OnPointerEnter(e);
}
/// <summary>
/// Called before the <see cref="PointerLeave"/> event occurs.
/// </summary>
/// <param name="e">The event args.</param>
private void OnPointerLeaveCore(PointerEventArgs e)
{
IsPointerOver = false;
OnPointerLeave(e);
}
/// <summary>
/// Updates the <see cref="IsEffectivelyEnabled"/> property based on the parent's
/// <see cref="IsEffectivelyEnabled"/>.
/// </summary>
/// <param name="parent">The parent control.</param>
private void UpdateIsEffectivelyEnabled(InputElement? parent)
{
IsEffectivelyEnabled = IsEnabledCore && (parent?.IsEffectivelyEnabled ?? true);
// PERF-SENSITIVE: This is called on entire hierarchy and using foreach or LINQ
// will cause extra allocations and overhead.
var children = VisualChildren;
// ReSharper disable once ForCanBeConvertedToForeach
for (int i = 0; i < children.Count; ++i)
{
var child = children[i] as InputElement;
child?.UpdateIsEffectivelyEnabled(this);
}
}
private void UpdatePseudoClasses(bool? isFocused, bool? isPointerOver)
{
if (isFocused.HasValue)
{
PseudoClasses.Set(":focus", isFocused.Value);
PseudoClasses.Set(":focus-visible", _isFocusVisible);
}
if (isPointerOver.HasValue)
{
PseudoClasses.Set(":pointerover", isPointerOver.Value);
}
}
}
}