Question

我知道，如何使用CanvasDrawingSession绘制具有笔触粗细的矩形。但是问题是，笔触粗细在矩形的内部和外部增长。我需要笔触粗细只能在矩形的内部增长。我不知道如何做到这一点！我试过的是？

我的xaml代码：

<Canvas x:Name="MyCanvas"> </Canvas>

我的c＃代码：

     private void Page_Loaded(object sender, RoutedEventArgs e)
    {
        CanvasVirtualControl canvasVirtualControl = new CanvasVirtualControl();
        canvasVirtualControl.Width = 1486;
        canvasVirtualControl.Height = 610;
        MyCanvas.Children.Add(canvasVirtualControl);
        Canvas.SetLeft(canvasVirtualControl, 0);
        Canvas.SetTop(canvasVirtualControl, 100);
        canvasVirtualControl.RegionsInvalidated += CanvasVirtualControl_RegionsInvalidated;
    }

    private void CanvasVirtualControl_RegionsInvalidated(CanvasVirtualControl sender, CanvasRegionsInvalidatedEventArgs args)
    {
        CanvasDrawingSession drawingSession;
        Rect rect = new Rect(args.InvalidatedRegions[0].Left, args.InvalidatedRegions[0].Top, args.InvalidatedRegions[0].Width, args.InvalidatedRegions[0].Height);

        using (drawingSession = sender.CreateDrawingSession(rect))
        {
            drawingSession.DrawRectangle(new Rect(0, 0, 200, 200), Windows.UI.Color.FromArgb(255, 255, 0, 0), 40);
        }
    }

为什么这样绘制矩形？我想这是因为矩形内部和外部都增加了笔触厚度。如何解决带有矩形厚度的绘制矩形仅在矩形内部生成？

更新的问题：

在使CanvasVirtualControl的整个区域无效的同时，笔触厚度在矩形的内部和外部增大。如果我使Invas无效的CanvasVirtualControl的特定矩形区域，strokeThickness仅在内部增大。

我的Xaml代码：

<Canvas x:Name="MyCanvas">
    <Button Content="InvalidateWholeRegion" Height="100" Canvas.Left="0" Canvas.Top="0" Click="InvalidateWholeRegion"/>
    <Button Content="InvalidateParticularRegion" Height="100" Canvas.Left="300" Canvas.Top="0" Click="InvalidateParticularRegion"/>
</Canvas>

我的c＃代码：

    CanvasVirtualControl canvasVirtualControl;
    private void Page_Loaded(object sender, RoutedEventArgs e)
    {
        canvasVirtualControl = new CanvasVirtualControl();
        canvasVirtualControl.Width = 1486;
        canvasVirtualControl.Height = 610;
        MyCanvas.Children.Add(canvasVirtualControl);
        Canvas.SetLeft(canvasVirtualControl, 0);
        Canvas.SetTop(canvasVirtualControl, 100);
        canvasVirtualControl.RegionsInvalidated += CanvasVirtualControl_RegionsInvalidated;
    }

    private void CanvasVirtualControl_RegionsInvalidated(CanvasVirtualControl sender, CanvasRegionsInvalidatedEventArgs args)
    {
        CanvasDrawingSession drawingSession;
        Rect rect = new Rect(args.InvalidatedRegions[0].Left, args.InvalidatedRegions[0].Top, args.InvalidatedRegions[0].Width, args.InvalidatedRegions[0].Height);
        using (drawingSession = sender.CreateDrawingSession(rect))
        {
            drawingSession.DrawRectangle(new Rect(rect.X, rect.Y, 100, 100), Windows.UI.Color.FromArgb(255, 255, 0, 0), 40);
        }
    }

    private void InvalidateParticularRegion(object sender, RoutedEventArgs e)
    {
        canvasVirtualControl.Invalidate(new Rect(200, 200, 100, 100));
    }
    private void InvalidateWholeRegion(object sender, RoutedEventArgs e)
    {
        canvasVirtualControl.Invalidate(new Rect(0, 0, 1486, 610));
    }

如何绘制笔划在使特定区域无效时，厚膜也会长到外面吗？

Answer 1

但是问题是，笔划厚度在矩形的内部和外部增大。我需要笔划厚度必须仅在矩形的内部增大。

DrawRectangle方法的绘制路径是笔画的中心，它是设计使然。当您将Rect设置为 0、0、200、200 时，捆绑包将裁剪左上角的一半。因此它将绘制一个如上的矩形。

如果要绘制完整的矩形，则需要确保起点是合理的值。因此，我们需要将Rect修改为 20、20、200、200 。

private void CanvasVirtualControl_RegionsInvalidated(CanvasVirtualControl sender, CanvasRegionsInvalidatedEventArgs args)
{
    CanvasDrawingSession drawingSession;
    Rect rect = new Rect(args.InvalidatedRegions[0].Left, args.InvalidatedRegions[0].Top, args.InvalidatedRegions[0].Width, args.InvalidatedRegions[0].Height);

    using (drawingSession = sender.CreateDrawingSession(rect))
    {
        var dashedStroke = new CanvasStrokeStyle()
        {
            LineJoin = CanvasLineJoin.Round
        };
        drawingSession.DrawRectangle(new Rect(20, 20, 200, 200), Windows.UI.Color.FromArgb(255, 255, 0, 0),40,dashedStroke);
    }
}

在Win2D中，如何绘制具有笔触粗细的矩形？

1 个答案: