在 Xamarin.Forms 中使用 SkiaSharp 将点击事件添加到 SVG 中的元素

Question

I want to get the particular points inside the svg for xamarin.forms Is there is any ways from which I can achieve?

Thanks in advance.

Answer 1

Answering this old question to maybe help future explorers like myself - in my app I went with SkiaSharp's own tap handlers that are on SKCanvas . You turn them on with the EnableTouchEvents property and then set the callback in the Touch property. Also, in the callback handler make sure to set e.Handled = true; on the SKTouchEventArgs or else you won't get the full spectrum of SKTouchAction types. Tap location is also included.

Answer 2

Yes you can add touch events to particular points using Skiasharp. You just have to filter actions by Locations. Assuming you are using Xaml and C#, you Xaml code would look like this

<Grid BackgroundColor="White"
        Grid.Row="1">

    <skia:SKCanvasView x:Name="canvasView"
                        PaintSurface="OnCanvasViewPaintSurface" />
    <Grid.Effects>
        <tt:TouchEffect Capture="True"
                        TouchAction="OnTouchEffectAction" />
    </Grid.Effects>
</Grid>

and then your C# would be like this

void OnTouchEffectAction(object sender, TouchActionEventArgs args)
{
    // Convert Xamarin.Forms point to pixels
    Point pt = args.Location;
    SKPoint point = 
        new SKPoint((float)(canvasView.CanvasSize.Width * pt.X / canvasView.Width),
                    (float)(canvasView.CanvasSize.Height * pt.Y / canvasView.Height));

    // Uncomment the code below based on what you specifically need
    // if (point != The Point you care about) or (pt != The Location you care about
        // return;
    switch (args.Type)
    {
        case TouchActionType.Pressed:
            if (bitmap.HitTest(point))
            {
                touchIds.Add(args.Id);
                bitmap.ProcessTouchEvent(args.Id, args.Type, point);
                break;
            }
            break;

        case TouchActionType.Moved:
            if (touchIds.Contains(args.Id))
            {
                bitmap.ProcessTouchEvent(args.Id, args.Type, point);
                canvasView.InvalidateSurface();
            }
            break;

        case TouchActionType.Released:
        case TouchActionType.Cancelled:
            if (touchIds.Contains(args.Id))
            {
                bitmap.ProcessTouchEvent(args.Id, args.Type, point);
                touchIds.Remove(args.Id);
                canvasView.InvalidateSurface();
            }
            break;
    }
}

Charles Petzold authored these Github examples with Skiasharp, check them out to get a better idea