SkiaSharp Canvas 按钮不起作用

SkiaSharp Canvas button doesn't work

我有一个 Xamrin Form 网格布局,如下所示。有一个SkiaSharp canvas 渐变色。我需要在 canvas 中添加一个按钮来获得渐变背景。但是当我在 canvas 中添加按钮时,它不会呈现任何内容(按钮 x:Name="ClickMe2")。使用渐变背景渲染按钮的正确方法是什么?

XAML

<Grid x:Name="controlGrid">
    <Grid.RowDefinitions>
        <RowDefinition Height="200" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>
    <views:SKCanvasView PaintSurface="OnSecondPainting" EnableTouchEvents="True" Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" >
        <Button x:Name="ClickMe2" Text="ClickMe 2" HeightRequest="50"  VerticalOptions="Start" />
    </views:SKCanvasView>
    <Label Text="Bottom Left" Grid.Row="1" Grid.Column="0" />
    <Button x:Name="ClickMe1" Text="ClickMe 1" Grid.Row="1" Grid.Column="1" HeightRequest="50"  VerticalOptions="Start" />
</Grid>

C#

    private void OnSecondPainting(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);


    }

这是因为 canvas 视图实际上不是布局 - 它是 View。也就是说不支持children.

如果这确实是个问题,请随时在 GitHub 上提出问题: https://github.com/mono/skiasharp/issues 我们可以在那里讨论这个问题,也可以从社区获得意见(例如更改或新观点)

如果您想将视图放在 canvas 之上,您可以使用 GridRelativeLayoutAbsoluteLayout:

<Grid>
    <views:SKCanvasView />
    <Button />
</Grid>

只要canvas是第一个child,其他children都会出现在它上面