以Xamarin形式在SkiaSharp画布上居中对齐圆

Question

I have following code which paints a circle on a canvas, in Xamarin Forms. I am specifying the position of the center of the circle as shown below.

  canvas.DrawCircle(100, 100, 150, circleFill);

What is the correct way to align the circle on the center of the canvas without specifying center position?

Note: I tried SKTextAlign.Center property of SKPaint inside circleFill and circleBorder. But that didn't help

    private void OnPainting(object sender, SKPaintSurfaceEventArgs e)
    {
        var surface = e.Surface;
        var canvas = surface.Canvas;
        canvas.Clear(SKColors.White);

        ///GRADIENT--------------------------------------------------------------------
        var colors = new SKColor[] { new SKColor(6, 107, 249), new SKColor(27, 162, 210) , new SKColor(36, 182, 197) };
        var shader = SKShader.CreateLinearGradient(new SKPoint(300, 0), new SKPoint(300, 600), colors, null, SKShaderTileMode.Clamp);
        var paint = new SKPaint() { Shader = shader };
        canvas.DrawPaint(paint);

        // DRAWING SHAPES
        var circleFill = new SKPaint
        {
            IsAntialias = true,
            Style = SKPaintStyle.Fill, //FILL
            Color = SKColors.Blue
        };
        canvas.DrawCircle(100, 100, 150, circleFill);

        var circleBorder = new SKPaint
        {
            IsAntialias = true,
            Style = SKPaintStyle.Stroke, //STROKE
            Color = SKColors.Teal,
            StrokeWidth = 15
        };
        canvas.DrawCircle(100, 100, 150, circleBorder);
    }

XAML

<Grid>
    <views:SKCanvasView PaintSurface="OnPainting" EnableTouchEvents="True" Touch="OnTouch">
    </views:SKCanvasView>
</Grid>

Answer 1

您可以根据画布大小来计算位置，例如

var x = e.Info.Width / 2;