XAML-Map-Control/MapControl/Shared/Map.cs

using System;
#if WPF
using System.Windows;
#elif UWP
using Windows.UI.Xaml;
#elif WINUI
using Microsoft.UI.Xaml;
#elif AVALONIA
using Avalonia;
#endif

namespace MapControl;

/// <summary>
/// MapBase with default input event handling.
/// </summary>
public partial class Map : MapBase
{
    public static readonly DependencyProperty MouseWheelZoomDeltaProperty =
        DependencyPropertyHelper.Register<Map, double>(nameof(MouseWheelZoomDelta), 0.25);

    public static readonly DependencyProperty MouseWheelZoomAnimatedProperty =
        DependencyPropertyHelper.Register<Map, bool>(nameof(MouseWheelZoomAnimated), true);

    /// <summary>
    /// Gets or sets the amount by which the ZoomLevel property changes by a MouseWheel event.
    /// The default value is 0.25.
    /// </summary>
    public double MouseWheelZoomDelta
    {
        get => (double)GetValue(MouseWheelZoomDeltaProperty);
        set => SetValue(MouseWheelZoomDeltaProperty, value);
    }

    /// <summary>
    /// Gets or sets a value that specifies whether zooming by a MouseWheel event is animated.
    /// The default value is true.
    /// </summary>
    public bool MouseWheelZoomAnimated
    {
        get => (bool)GetValue(MouseWheelZoomAnimatedProperty);
        set => SetValue(MouseWheelZoomAnimatedProperty, value);
    }

    private void OnMouseWheel(Point position, double delta)
    {
        var zoomLevel = TargetZoomLevel + MouseWheelZoomDelta * delta;
        var animated = false;

        if (delta <= -1d || delta >= 1d)
        {
            // Zoom to integer multiple of MouseWheelZoomDelta when the event was raised by a
            // mouse wheel or by a large movement on a touch pad or other high resolution device.
            //
            zoomLevel = MouseWheelZoomDelta * Math.Round(zoomLevel / MouseWheelZoomDelta);
            animated = MouseWheelZoomAnimated;
        }

        ZoomMap(position, zoomLevel, animated);
    }
}