我可以在 Xamarin 项目中绘制 XAML 的圆形、椭圆形或正方形吗？

Question

很好，我想在 Xamarin 项目中绘制圆形、正方形、椭圆形和三角形，但我找不到如何在 UWP 中这样做：

<StackPanel>
     <Ellipse Fill="Yellow"
              Height="100"
              Width="200"
              StrokeThickness="2"
              Stroke="Black"/>
</StackPanel>

问题是我不知道我是否需要 NuGet 包或 Xamarin 中的一些补充

Answer 1

如果要画圆（只能通过代码实现），可以参考下面的代码。

public class SimpleCirclePage : ContentPage
{
    public SimpleCirclePage()
    {


        SKCanvasView canvasView = new SKCanvasView();
        canvasView.PaintSurface += OnCanvasViewPaintSurface;
        Content = canvasView;
    }

    void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
    {
        SKImageInfo info = args.Info;
        SKSurface surface = args.Surface;
        SKCanvas canvas = surface.Canvas;

        canvas.Clear();

        SKPaint paint = new SKPaint
        {
            Style = SKPaintStyle.Stroke,
            Color = Color.Red.ToSKColor(),
            StrokeWidth = 10
        };
        canvas.DrawCircle(info.Width / 3, info.Height / 2, 100, paint);

    }
}

详情：https://docs.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/basics/circle

如果想用XAML和代码画椭圆，可以参考下面的代码。

在XAML

 <ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:skia="clr- namespace:SkiaSharp.Views.Forms;assembly=SkiaSharp.Views.Forms"
         x:Class="SkiaSharpFormsDemos.Basics.EllipseFillPage"
         Title="Ellipse Fill">

<skia:SKCanvasView PaintSurface="OnCanvasViewPaintSurface" />

代码

public partial class EllipseFillPage : ContentPage
{
    public EllipseFillPage()
    {
        InitializeComponent();
    }

    void OnCanvasViewPaintSurface(object sender, SKPaintSurfaceEventArgs args)
    {
        SKImageInfo info = args.Info;
        SKSurface surface = args.Surface;
        SKCanvas canvas = surface.Canvas;

        canvas.Clear();

        float strokeWidth = 5;
        float xRadius = (info.Width - strokeWidth) / 3;
        float yRadius = (info.Height - strokeWidth) / 3;

        SKPaint paint = new SKPaint
        {
            Style = SKPaintStyle.Stroke,
            Color = SKColors.Black,
            StrokeWidth = strokeWidth
        };
        canvas.DrawOval(info.Width / 2, info.Height / 2, xRadius, yRadius, paint);
    }
}

如果你想画出只使用 XAML 的锐利方式（就像在 UWP 中一样），你可以下载 this plugin .

我可以在 Xamarin 项目中绘制 XAML 的圆形、椭圆形或正方形吗？

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