C#鼠标拖拽，移动图片实例

最近工作需要做一个鼠标可以拖拽移动图片的功能。

写了几个基本功能，勉强能用。这里记录一下。欢迎大神补充。

这个就是完成的功能。

下边的绿色是一个pictureBox，白色框也是一个pictureBox，他们二者是子父级关系。

绿色是父级，白色框是子级。

这里插一个知识点：关于pictureBox的

白色框的pictureBox，我添加的image属性的图片是一张中心透明四周是白边回来Png图片，这个需要注意一下。

1：子级pictureBox如何在父级PictureBox上透明显示。添加下边这句话：

// 设置背景颜色为系统定义的颜色
pictureBox2.BackColor = Color.Transparent;

2：背景透明设置完成，但是现在还是不能够拖拽四周或四个角改变大小。添加下边这句话：

// 设置pictureBox大小可拖拽
pictureBox2.SizeMode = PictureBoxSizeMode.StretchImage;

到这里，小的pictureBox就已经背景透明并且可拖拽的显示在其父级上边了。

下边是我测试使用的Form1.cs文件的代码：

实例放在文末的压缩包中，有兴趣可以尝试下。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Threading;
 
namespace cutCScan
{
    public partial class Form1 : Form
    {
        // 截取数据，获得对角线两点坐标。取到要截取的平面区域。
        // 平面区域中有若干个A扫，取其峰值，上下各加一个固定阈值（50）
        // 将此块数据都截取下来。
 
        public Form1()
        {
            InitializeComponent();
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            // 设置背景颜色为系统定义的颜色
            pictureBox2.BackColor = Color.Transparent;
            pictureBox2.Parent = pictureBox1;
            //pictureBox2.BackgroundImageLayout = ImageLayout.Stretch;//设置背景图片自动适应
            // 设置pictureBox大小可拖拽
            pictureBox2.SizeMode = PictureBoxSizeMode.StretchImage;
        }
 
 
        /// <summary>
        ///  有关鼠标样式的相关枚举
        /// </summary>
        private enum EnumMousePointPosition
        {
            MouseSizeNone = 0, //无
            MouseSizeRight = 1, //拉伸右边框
            MouseSizeLeft = 2,  //拉伸左边框
            MouseSizeBottom = 3, //拉伸下边框
            MouseSizeTop = 4, //拉伸上边框
            MouseSizeTopLeft = 5,//拉伸左上角
            MouseSizeTopRight = 6,//拉伸右上角
            MouseSizeBottomLeft = 7,//拉伸左下角
            MouseSizeBottomRight = 8,//拉伸右下角
            MouseDrag = 9 //鼠标拖动
        }
 
        #region 鼠标移动变量
        const int Band = 5;//范围半径
        const int MinWidth = 10;//最低宽度
        const int MinHeight = 10;//最低高度
        private EnumMousePointPosition m_MousePointPosition; //鼠标样式枚举
        private Point m_lastPoint; //光标上次移动的位置
        private Point m_endPoint; //光标移动的当前位置
 
 
        #endregion
 
       
 
        /// <summary>
        /// 鼠标按下事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox2_MouseDown(object sender, MouseEventArgs e)
        {
            m_lastPoint.X = e.X;
            m_lastPoint.Y = e.Y;
            m_endPoint.X = e.X;
            m_endPoint.Y = e.Y;
        }
 
        /// <summary>
        /// 鼠标离开控件的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox2_MouseLeave(object sender, EventArgs e)
        {
            m_MousePointPosition = EnumMousePointPosition.MouseSizeNone;
            this.Cursor = Cursors.Arrow;
        }
        /// <summary>
        /// 鼠标移过控件的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void pictureBox2_MouseMove(object sender, MouseEventArgs e)
        {
            Control lCtrl = (sender as Control);//获得事件源
            //左键按下移动
            if (e.Button == MouseButtons.Left)
            {
                switch (m_MousePointPosition)
                {
                    case EnumMousePointPosition.MouseDrag:
                        lCtrl.Left = lCtrl.Left + e.X - m_lastPoint.X;
                        lCtrl.Top = lCtrl.Top + e.Y - m_lastPoint.Y;
                        break;
                    case EnumMousePointPosition.MouseSizeBottom:
                        lCtrl.Height = lCtrl.Height + e.Y - m_endPoint.Y;
                        m_endPoint.X = e.X;
                        m_endPoint.Y = e.Y; //记录光标拖动的当前点                     
                        break;
                    case EnumMousePointPosition.MouseSizeBottomRight:
                        lCtrl.Width = lCtrl.Width + e.X - m_endPoint.X;
                        lCtrl.Height = lCtrl.Height + e.Y - m_endPoint.Y;
                        m_endPoint.X = e.X;
                        m_endPoint.Y = e.Y; //记录光标拖动的当前点     
                        break;
                    case EnumMousePointPosition.MouseSizeRight:
                        lCtrl.Width = lCtrl.Width + e.X - m_endPoint.X;
                        lCtrl.Height = lCtrl.Height + e.Y - m_endPoint.Y;
                        m_endPoint.X = e.X;
                        m_endPoint.Y = e.Y; //记录光标拖动的当前点
                        break;
                    case EnumMousePointPosition.MouseSizeTop:
                        lCtrl.Top = lCtrl.Top + (e.Y - m_lastPoint.Y);
                        lCtrl.Height = lCtrl.Height - (e.Y - m_lastPoint.Y);
                        break;
                    case EnumMousePointPosition.MouseSizeLeft:
                        lCtrl.Left = lCtrl.Left + e.X - m_lastPoint.X;
                        lCtrl.Width = lCtrl.Width - (e.X - m_lastPoint.X);
                        break;
                    case EnumMousePointPosition.MouseSizeBottomLeft:
                        lCtrl.Left = lCtrl.Left + e.X - m_lastPoint.X;
                        lCtrl.Width = lCtrl.Width - (e.X - m_lastPoint.X);
                        lCtrl.Height = lCtrl.Height + e.Y - m_endPoint.Y;
                        m_endPoint.X = e.X;
                        m_endPoint.Y = e.Y; //记录光标拖动的当前点
                        break;
                    case EnumMousePointPosition.MouseSizeTopRight:
                        lCtrl.Top = lCtrl.Top + (e.Y - m_lastPoint.Y);
                        lCtrl.Width = lCtrl.Width + (e.X - m_endPoint.X);
                        lCtrl.Height = lCtrl.Height - (e.Y - m_lastPoint.Y);
                        m_endPoint.X = e.X;
                        m_endPoint.Y = e.Y; //记录光标拖动的当前点        
                        break;
                    case EnumMousePointPosition.MouseSizeTopLeft:
                        lCtrl.Left = lCtrl.Left + e.X - m_lastPoint.X;
                        lCtrl.Top = lCtrl.Top + (e.Y - m_lastPoint.Y);
                        lCtrl.Width = lCtrl.Width - (e.X - m_lastPoint.X);
                        lCtrl.Height = lCtrl.Height - (e.Y - m_lastPoint.Y);
                        break;
                    default:
                        break;
                }
                if (lCtrl.Width < MinWidth) lCtrl.Width = MinWidth;
                if (lCtrl.Height < MinHeight) lCtrl.Height = MinHeight;
            }
            else
            {
                //'判断光标的位置状态
                m_MousePointPosition = MousePointPosition(lCtrl.Size, e);
                switch (m_MousePointPosition)  //改变光标
                {
                    case EnumMousePointPosition.MouseSizeNone:
                        this.Cursor = Cursors.Arrow;//箭头
                        break;
                    case EnumMousePointPosition.MouseDrag:
                        this.Cursor = Cursors.SizeAll;//四方向
                        break;
                    case EnumMousePointPosition.MouseSizeBottom:
                        this.Cursor = Cursors.SizeNS;//南北
                        break;
                    case EnumMousePointPosition.MouseSizeTop:
                        this.Cursor = Cursors.SizeNS;//南北
                        break;
                    case EnumMousePointPosition.MouseSizeLeft:
                        this.Cursor = Cursors.SizeWE;//东西
                        break;
                    case EnumMousePointPosition.MouseSizeRight://*/
                        this.Cursor = Cursors.SizeWE;//东西
                        break;
                    case EnumMousePointPosition.MouseSizeBottomLeft:
                        this.Cursor = Cursors.SizeNESW;//东北到南西
                        break;
                    case EnumMousePointPosition.MouseSizeBottomRight:
                        this.Cursor = Cursors.SizeNWSE;//东南到西北
                        break;
                    case EnumMousePointPosition.MouseSizeTopLeft:
                        this.Cursor = Cursors.SizeNWSE;//东南到西北
                        break;
                    case EnumMousePointPosition.MouseSizeTopRight:
                        this.Cursor = Cursors.SizeNESW;//东北到南西
                        break;
                    default:
                        break;
                }
            }
        }
 
        /// <summary>
        /// 坐标位置判定
        /// </summary>
        /// <param name="size"></param>
        /// <param name="e"></param>
        /// <returns></returns>
        private EnumMousePointPosition MousePointPosition(Size size, System.Windows.Forms.MouseEventArgs e)
        {
            if ((e.X >= -1 * Band) | (e.X <= size.Width) |
                (e.Y >= -1 * Band) | (e.Y <= size.Height))
            {
                if (e.X < Band)
                {
                    if (e.Y < Band)
                    {
                        return EnumMousePointPosition.MouseSizeTopLeft;
                    }
                    else
                    {
                        if (e.Y > -1 * Band + size.Height)
                        {
                            return EnumMousePointPosition.MouseSizeBottomLeft;
                        }
                        else
                        {
                            return EnumMousePointPosition.MouseSizeLeft;
                        }
                    }
                }
                else
                {
                    if (e.X > -1 * Band + size.Width)
                    {
                        if (e.Y < Band)
                        { return EnumMousePointPosition.MouseSizeTopRight; }
                        else
                        {
                            if (e.Y > -1 * Band + size.Height)
                            { return EnumMousePointPosition.MouseSizeBottomRight; }
                            else
                            {
                                return EnumMousePointPosition.MouseSizeRight;
                            }
                        }
                    }
                    else
                    {
                        if (e.Y < Band)
                        {
                            return EnumMousePointPosition.MouseSizeTop;
                        }
                        else
                        {
                            if (e.Y > -1 * Band + size.Height)
                            {
                                return EnumMousePointPosition.MouseSizeBottom;
                            }
                            else
                            { return EnumMousePointPosition.MouseDrag; }
                        }
                    }
                }
            }
            else
            { return EnumMousePointPosition.MouseSizeNone; }
        }
    }
}

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