c#中按鼠标左键拖动鼠标绘出虚线矩形

Question

winform中 在panel控件中按下鼠标左键后拖动鼠标绘出虚线矩形，松开鼠标键后虚线矩形隐藏

Answer 1

在 MouseDown 和 MouseUp 事件中处理，通过 e.X 和 e.Y 得到座标，进行画线处理。

Answer 2

参考下： private Point m_DownPoint;
private Point m_CurPoint;
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
this.m_DownPoint = this.PointToScreen(e.Location);
this.m_CurPoint = this.PointToScreen(e.Location);
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (this.Capture)
{
Point curPoint = this.PointToScreen(e.Location);
ControlPaint.DrawReversibleFrame(Rectangle.FromLTRB(this.m_DownPoint.X, this.m_DownPoint.Y, this.m_CurPoint.X, this.m_CurPoint.Y), Color.Yellow, FrameStyle.Dashed);
ControlPaint.DrawReversibleFrame(Rectangle.FromLTRB(this.m_DownPoint.X, this.m_DownPoint.Y, curPoint.X, curPoint.Y), Color.Yellow, FrameStyle.Dashed);
this.m_CurPoint = curPoint;
}
}
protected override void OnMouseUp(MouseEventArgs e)
{
base.OnMouseUp(e);
ControlPaint.DrawReversibleFrame(Rectangle.FromLTRB(this.m_DownPoint.X, this.m_DownPoint.Y, this.m_CurPoint.X, this.m_CurPoint.Y), Color.Yellow, FrameStyle.Dashed);
}
protected override void OnDeactivate(EventArgs e)
{
base.OnDeactivate(e);
ControlPaint.DrawReversibleFrame(Rectangle.FromLTRB(this.m_DownPoint.X, this.m_DownPoint.Y, this.m_CurPoint.X, this.m_CurPoint.Y), Color.Yellow, FrameStyle.Dashed);
}

Answer 3

http://blog.csdn.net/zgke/archive/2008/12/12/3502920.aspx

Answer 4

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;namespace WindowsFormsApplication27
{
    public partial class Form1 : Form
    {
        Point StartPoint;        public Form1()
        {
            InitializeComponent();
            this.MouseMove += new MouseEventHandler(Form1_MouseMove);
            this.MouseUp+=new MouseEventHandler(Form1_MouseUp);
        }
        void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button != MouseButtons.Left)
                StartPoint = e.Location;
            else using (Graphics G = this.CreateGraphics())
                {
                    Point Start = StartPoint;
                    Point End = e.Location;
                    int Width = e.X - Start.X;
                    int Height = e.Y - Start.Y;                    if (Width < 0)
                    {
                        Start.X += Width;
                        End.X -= Width;
                    }
                    if (Height < 0)
                    {
                        Start.Y += Height;
                        End.Y -= Height;
                    }                    G.Clear(this.BackColor);
                
                 
                    ControlPaint.DrawFocusRectangle(G, new Rectangle(Start, new Size(Math.Abs(Width), Math.Abs(Height))));
                }
        }
        void Form1_MouseUp(object sender, MouseEventArgs e)
        {
               
        }
    }    
}