C#如何像在Windows资源管理器中一样在面板上绘制橡皮筋选择矩形? [英] C# How to Draw a Rubber Band Selection Rectangle on Panel, like one used in Windows Explorer?

问题描述

我有一个Flow Layout Panel，其中包含一些用户控件.我想使用鼠标使用矩形选择来选择这些控件，就像在Windows文件浏览器中使用的那样.我已经尝试过这些操作: https://support.microsoft.com/en-us/kb/314945 但这是非常闪烁的，没有用(我可能是错的，请纠正我).请提供任何好的示例.

I have one Flow Layout Panel with some User Controls in it. I Want to Select these controls using rectangle selection using Mouse,like one used in windows file explorer . I have tried these : https://support.microsoft.com/en-us/kb/314945 But it was very flickering and not useful (I might be wrong,please correct me). Any good examples please.

推荐答案

绘制橡皮筋矩形是这样的:

Drawing the rubber-band rectangle is done like this:

private void panel1_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == System.Windows.Forms.MouseButtons.Left)
    {
        panel1.Refresh();
        using (Graphics g = panel4.CreateGraphics())
        {
            Rectangle rect = GetRectangle(mdown, e.Location);
            g.DrawRectangle(Pens.Red, rect);
        }
    }

}

private void panel1_MouseDown(object sender, MouseEventArgs e)
{
    mdown = e.Location;
}

它使用辅助功能:

static public Rectangle GetRectangle(Point p1, Point p2)
{
    return new Rectangle(Math.Min(p1.X, p2.X), Math.Min(p1.Y, p2.Y),
        Math.Abs(p1.X - p2.X), Math.Abs(p1.Y - p2.Y));
}

我没有任何闪烁.如果这样做，也许您已经编码了 Paint 事件，则可能要使用双缓冲的 Panel :

I don't get any flicker from it. If you do, maybe you have coded the Paint event, you may want to use a double-buffered Panel:

class DrawPanel : Panel 
{
   public DrawPanel()
    {
        DoubleBuffered = true;
    }
}

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更新:您可以使用代替 Panel ，后者是 Container 控件，并不是真正要使用的控件> Picturebox 或 Label (带有 Autosize = false )；两者都具有开箱即用的 DoubleBuffered 属性，并且比 Panels 更好地支持绘图.

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Update: Instead of a Panel, which is a Container control and not really meant to draw onto, you can use a Picturebox or a Label (with Autosize=false); both have the DoubleBuffered property turned on out of the box and support drawing better than Panels do.

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