WPF中如何绘制矩形？

问题描述

我需要在画布上绘制矩形。
我知道怎么画。但我没有这样做，将利用360度

为例。蓝色，淡紫色，绿色他们是同一个矩形，我改变例如
红点颜色开始位置的矩形。

编辑：

我的行为：

LeftMouseDown以x = 50; y = 50（按）
MoveMouse到100; 100 - 现在，它的工作原理
MoveMouse 30; 150或MoveMouse 10; 10 - 现在，我不能这样做，但我需要它

解决方案

除非你需要一个旋转矩形我不会理会使用变换。只需设置Left和Top到最小x和y和宽度到最大-x和高度MAXY-γ

<帆布X：NAME =画布的MouseDown =Canvas_MouseDown的MouseMove =Canvas_MouseMove的MouseUp =Canvas_MouseUp背景=透明/>


 私人点的startPoint; 
私人矩形RECT; 
 
私人无效Canvas_MouseDown（对象发件人，MouseButtonEventArgs E）
 {
的startPoint = e.GetPosition（画布）; 
 
 RECT =新的Rectangle 
 {
行程= Brushes.LightBlue，
 StrokeThickness = 2 
}; 
 Canvas.SetLeft（RECT，startPoint.X）; 
 Canvas.SetTop（RECT，startPoint.X）; 
 canvas.Children.Add（RECT）; 
} 
 
私人无效Canvas_MouseMove（对象发件人，MouseEventArgs E）
 {
如果（e.LeftButton == || MouseButtonState.Released矩形== NULL）
返回; 
 
 VAR POS = e.GetPosition（画布）; 
 
变种X = Math.Min（pos.X，startPoint.X）; 
变种Y = Math.Min（pos.Y，startPoint.Y）; 
 
变种W = Math.Max​​（pos.X，startPoint.X） -  X; 
 VAR H = Math.Max​​（pos.Y，startPoint.Y） - Ÿ; 
 
 rect.Width = W; 
 rect.Height = H; 
 
 Canvas.SetLeft（RECT，X）; 
 Canvas.SetTop（RECT，Y）; 
} 
 
私人无效Canvas_MouseUp（对象发件人，MouseButtonEventArgs E）
 {
 RECT = NULL; 
} 
  

I need draw rectangle in canvas.I know how to draw. But I did not get to do so would draw on a 360-degree

Example. blue, lilac, green they are one and the same rectangle, I changed the color for exampleRed point is start position rectangle.

EDIT:

My actions:

LeftMouseDown in x=50;y=50 (press)MoveMouse to 100;100 - now it worksMoveMouse to 30;150 or MoveMouse to 10;10 - Now I can not do this, but I need it

解决方案

Unless you need a rotated rectangle I wouldn't bother using transforms. Just set Left and Top to the minimum x and y and width to max-x and height maxy-y.

<Canvas x:Name="canvas" MouseDown="Canvas_MouseDown" MouseMove="Canvas_MouseMove" MouseUp="Canvas_MouseUp" Background="Transparent" />

private Point startPoint;
private Rectangle rect;

private void Canvas_MouseDown(object sender, MouseButtonEventArgs e)
{
    startPoint = e.GetPosition(canvas);

    rect = new Rectangle
    {
        Stroke = Brushes.LightBlue,
        StrokeThickness = 2
    };
    Canvas.SetLeft(rect,startPoint.X);
    Canvas.SetTop(rect,startPoint.X);
    canvas.Children.Add(rect);
}

private void Canvas_MouseMove(object sender, MouseEventArgs e)
{
    if(e.LeftButton == MouseButtonState.Released || rect == null)
        return;

    var pos = e.GetPosition(canvas);

    var x = Math.Min(pos.X, startPoint.X);
    var y = Math.Min(pos.Y, startPoint.Y);

    var w = Math.Max(pos.X, startPoint.X) - x;
    var h = Math.Max(pos.Y, startPoint.Y) - y;

    rect.Width = w;
    rect.Height = h;

    Canvas.SetLeft(rect, x);
    Canvas.SetTop(rect, y);
}

private void Canvas_MouseUp(object sender, MouseButtonEventArgs e)
{
    rect = null;
}

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