c# - 我可以在 Xamarin 项目的 XAML 中绘制圆形、椭圆或正方形吗？

Question

很好，我想在 Xamarin 项目中绘制圆形、正方形、椭圆和三角形，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 中的一些补充包

Answer 1

如果要画圆(只能通过代码实现)，可以引用下面的代码。

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

如果你想使用XAML和代码来绘制椭圆，你可以引用下面的代码。

在 XAML 中

 <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);
    }
}

如果您想绘制仅使用 XAML 的锐线方式(如在 UWP 中)，您可以下载 this plugin .