win2D CanvasControl DrawImage() 通过错误"Value Does Not Fall Within the expected Range"？

Question

我尝试了什么？ XAML代码：

 <Canvas x:Name="grid">
<canvas:CanvasControl Draw="CanvasControl_Draw" CreateResources="CanvasControl_CreateResourcesAsync" ></canvas:CanvasControl>
    </Canvas>

C#代码：

CanvasBitmap canvasBitmap;
private async void CanvasControl_CreateResourcesAsync(CanvasControl sender, Microsoft.Graphics.Canvas.UI.CanvasCreateResourcesEventArgs args)
{
  canvasBitmap = await CanvasBitmap.LoadAsync(sender, @"Assets\Square150x150Logo.scale-200.png");
  sender.Invalidate();
}
private void  CanvasControl_Draw(CanvasControl sender, CanvasDrawEventArgs args)
{
   Vector2 Vector = new Vector2();
   Vector.X = 10;
   Vector.Y = 10;
   args.DrawingSession.DrawImage(canvasBitmap,Vector);          
}

在使用 Canvas 时，Canvas 控件不会触发绘制事件，如果我使用 Grid 而不是 Canvas，它会触发 [=21= 的绘制事件]控制。我需要 Canvas 在后台。错误 "The Value does Not Fall Within The Expected Range " 也 occurs.Can 有人帮我吗？？

Answer 1

While using Canvas,the CanvasControl won't fire the Draw Event

Canvas是一个使用绝对定位的控件。 CanvasControl在没有显式设置Width或Height的情况下不会渲染，自然不会触发Draw事件。

如果要触发Draw事件，请设置CanvasControl的Width和Height属性，如：

<Canvas x:Name="grid">
    <canvas:CanvasControl Draw="CanvasControl_Draw" 
                          CreateResources="CanvasControl_CreateResources"
                          Width="500" Height="500"
                          />
</Canvas>

The Error "The Value does Not Fall Within The Expected Range " also occurs.

简单来说，这个错误的原因是Draw方法准备渲染尚未加载的图像。

如果想在CreateResources事件中处理异步方法，比如图片加载，可以考虑这样做：

CanvasBitmap canvasBitmap;
private void CanvasControl_CreateResources(CanvasControl sender, Microsoft.Graphics.Canvas.UI.CanvasCreateResourcesEventArgs args)
{
    args.TrackAsyncAction(CreateResourceAsync(sender).AsAsyncAction());
    sender.Invalidate();
}

private async Task CreateResourceAsync(CanvasControl sender)
{
    canvasBitmap = await CanvasBitmap.LoadAsync(sender, @"Assets\Square150x150Logo.scale-200.png");
}

这确保了 Draw 事件不会在 CreateResources 事件结束之前被触发。

谢谢。

win2D CanvasControl DrawImage() 通过错误"Value Does Not Fall Within the expected Range"？

win2D CanvasControl DrawImage() throughs the error "Value Does Not Fall Within the expected Range"?

c#

uwp

win2d