WPF的重复绘制问题

Question

别的语言，可以自定义绘制，比如我创建1个矩形对象，然后，我用循环，把这个矩形画上100遍。

但WPF，非要建立100个矩形，添加进canvas，让它自己画。

请问如何实现，1个矩形，在 canvas上画100遍

Answer 1

DrawingContext.DrawRectangle(Brush, Pen, Rect)

Answer 2

在WPF里面是用DrawingContext去完成“画”图形的， 你可以参考：

http://msdn.microsoft.com/en-us/library/system.windows.media.drawingcontext.aspx

我给你写了一个sample：

public class MyVisualHost : FrameworkElement

{

    private VisualCollection _children;

 

    public MyVisualHost()

    {

        _children = new VisualCollection(this);

 

        _children.Add(CreateDrawingVisualRectangle());

 

    }

    protected override int VisualChildrenCount

    {

        get { return _children.Count; }

    }

 

    protected override Visual GetVisualChild(int index)

    {

        if (index < 0 || index >= _children.Count)

        {

            throw new ArgumentOutOfRangeException();

        }

 

        return _children[index];

    }

    private DrawingVisual CreateDrawingVisualRectangle()

    {

        DrawingVisual drawingVisual = new DrawingVisual();

 

        DrawingContext drawingContext = drawingVisual.RenderOpen();

        int position = 0;

 

        for (int i = 0; i < 100; i++)

        {

            Rect rect = new Rect(new System.Windows.Point(position, position), new System.Windows.Size(10, 10));

            drawingContext.DrawRectangle(System.Windows.Media.Brushes.Red, (System.Windows.Media.Pen)null, rect);

            position += 10;

        }

        drawingContext.Close();

 

        return drawingVisual;

    }

}

然后你就可以只创建一个对象，添加到Canvas就可以了，比如：

MyVisualHost test = new MyVisualHost();

canvas.Children.Add(test);

 

---

Sheldon _Xiao[MSFT]
MSDN Community Support | Feedback to us
Get or Request Code Sample from Microsoft
Please remember to mark the replies as answers if they help and unmark them if they provide no help.

Answer 3

谢谢大家