avalonia-input-interaction

name	avalonia-input-interaction
description	Use when handling pointer events, keyboard input, gestures, focus, drag-and-drop, or hot keys in Avalonia. Covers PointerPressed/Released/Moved, KeyDown/KeyUp, TextInput, HotKeyManager, KeyGesture, focus management, TapGestureRecognizer, PinchGestureRecognizer, DragDrop.DoDragDrop, DataObject, and Cursor types.

Avalonia Input & Interaction

Overview

All input routes as routed events (bubbling by default, tunneling with "Preview" prefix). Pointer events are unified across mouse, touch, and stylus.

Pointer Events

Event	Fires when
PointerPressed	Button/finger down
PointerReleased	Button/finger up
PointerMoved	Pointer moves over control
PointerEntered	Pointer enters bounds
PointerExited	Pointer leaves bounds
PointerCaptureLost	Capture released
Tapped	Quick tap/click
DoubleTapped	Double tap/click
RightTapped	Right-click / long press

myControl.PointerPressed += (s, e) =>
{
    var point = e.GetPosition(myControl);
    var props = e.GetCurrentPoint(myControl).Properties;
    if (props.IsLeftButtonPressed) { /* left click */ }
    if (props.IsRightButtonPressed) { /* right click */ }
    if (props.IsMiddleButtonPressed) { /* middle click */ }
};

Capture pointer (receive events outside bounds):

myControl.PointerPressed += (s, e) =>
{
    e.Pointer.Capture(myControl);
};
myControl.PointerReleased += (s, e) =>
{
    e.Pointer.Capture(null); // release
};

Check pointer type:

myControl.PointerPressed += (s, e) =>
{
    if (e.Pointer.Type == PointerType.Touch) { /* touch */ }
    if (e.Pointer.Type == PointerType.Pen) { /* stylus */ }
};

Keyboard Events

Event	Fires when
KeyDown	Key pressed (repeats while held)
KeyUp	Key released
TextInput	Text character produced

myControl.KeyDown += (s, e) =>
{
    if (e.Key == Key.Enter && e.KeyModifiers == KeyModifiers.Control)
    {
        e.Handled = true; // stop bubbling + prevent default
        SubmitForm();
    }
};

myTextBox.TextInput += (s, e) =>
{
    if (!char.IsDigit(e.Text![0]))
        e.Handled = true; // block non-digit input
};

KeyModifiers flags: None, Alt, Control, Shift, Meta (combinable with |)

// Ctrl+Shift+Z
if (e.Key == Key.Z && e.KeyModifiers == (KeyModifiers.Control | KeyModifiers.Shift))

Hot Keys

XAML registration:

<Button HotKey="Ctrl+S" Command="{Binding SaveCommand}" Content="Save"/>
<MenuItem HotKey="Ctrl+Z" Header="Undo" Command="{Binding UndoCommand}"/>

Code registration:

HotKeyManager.RegisterHotKey(myControl, new KeyGesture(Key.S, KeyModifiers.Control));
HotKeyManager.SetHotKey(myButton, new KeyGesture(Key.F5));

Unregister:

HotKeyManager.SetHotKey(myControl, null);

Focus

// Programmatic focus
myControl.Focus();

// Via FocusManager
var fm = TopLevel.GetTopLevel(this)?.FocusManager;
fm?.Focus(myControl, NavigationMethod.Tab);

// Get currently focused element
var focused = fm?.GetFocusedElement();

XAML focus control:

<TextBox IsTabStop="False"/>           <!-- exclude from tab order -->
<TextBox TabIndex="2"/>                <!-- explicit tab order -->
<TextBox AutoFocus="True"/>            <!-- focus on load (Avalonia 11.1+) -->

Pseudoclasses for styling:

<Style Selector="TextBox:focus">
    <Setter Property="BorderBrush" Value="Blue"/>
</Style>
<Style Selector="Button:focus-visible">
    <Setter Property="BorderThickness" Value="2"/>
</Style>

Focus scope (contains Tab navigation):

<Panel FocusManager.IsFocusScope="True">
    <!-- Tab cycles within this panel -->
</Panel>

Gesture Recognizers

Add to any InputElement.GestureRecognizers:

<Border Background="LightBlue" Width="200" Height="200">
    <Border.GestureRecognizers>
        <TapGestureRecognizer Tapped="OnTapped"/>
        <PinchGestureRecognizer PinchUpdated="OnPinchUpdated"/>
    </Border.GestureRecognizers>
</Border>

private void OnPinchUpdated(object? sender, PinchEventArgs e)
{
    _scale *= e.Scale;
    myBorder.RenderTransform = new ScaleTransform(_scale, _scale);
}

Recognizer	Events
TapGestureRecognizer	Tapped
DoubleTapGestureRecognizer	DoubleTapped
PinchGestureRecognizer	PinchUpdated, PinchEnded
PullGestureRecognizer	PullDelta, PullEnded
ScrollGestureRecognizer	ScrollGesture, ScrollGestureEnded, ScrollGestureInertiaStarting

Drag and Drop

Source (initiates drag):

private async void OnPointerPressed(object? sender, PointerPressedEventArgs e)
{
    var data = new DataObject();
    data.Set(DataFormats.Text, "dragged text");
    data.Set("custom/format", myObject);

    var result = await DragDrop.DoDragDrop(e, data,
        DragDropEffects.Copy | DragDropEffects.Move);
    // result: DragDropEffects indicating what happened
}

Target (receives drop):

<Border DragDrop.AllowDrop="True"
        Drop="OnDrop"
        DragOver="OnDragOver"
        DragEnter="OnDragEnter"
        DragLeave="OnDragLeave"/>

private void OnDragOver(object? sender, DragEventArgs e)
{
    e.DragEffects = e.Data.Contains(DataFormats.Text)
        ? DragDropEffects.Copy
        : DragDropEffects.None;
    e.Handled = true;
}

private void OnDrop(object? sender, DragEventArgs e)
{
    if (e.Data.Contains(DataFormats.Text))
    {
        var text = e.Data.GetText();
        // use text
    }
    if (e.Data.Contains(DataFormats.Files))
    {
        var files = e.Data.GetFiles();
        // IEnumerable<IStorageItem>
    }
}

Built-in DataFormats: Text, Files, FileNames

Cursor

<Border Cursor="Hand"/>
<TextBox Cursor="IBeam"/>
<Border Cursor="Wait"/>

Available cursors: Default, Arrow, Cross, Hand, Help, IBeam, No, SizeAll, SizeNESW, SizeNS, SizeNWSE, SizeWE, TopSide, BottomSide, LeftSide, RightSide, Wait, None

Custom cursor from bitmap:

var cursor = new Cursor(myBitmap, new PixelPoint(hotspotX, hotspotY));
myControl.Cursor = cursor;

Scroll Events

myControl.PointerWheelChanged += (s, e) =>
{
    var delta = e.Delta; // Vector: X for horizontal, Y for vertical
    ScrollBy(-delta.Y * 30);
};

Common Mistakes

• Not setting e.Handled = true on KeyDown — event bubbles to parent; TextBox will still consume keys
• DragDrop.DoDragDrop must be called on pointer event — calling after await loses the pointer event context
• Focus() before control is attached to visual tree — silently does nothing; call in OnAttachedToVisualTree or later
• Gesture recognizers vs. events — Tapped/DoubleTapped fire on InputElement directly; TapGestureRecognizer needed only for custom gesture behavior
• DragDrop.AllowDrop is an attached property — must be set on the drop target, not a parent
• PointerPressed fires before Tapped — don't handle both if one is sufficient