我所说的“鼠标拖拽效果”是指，鼠标在某个图标上按下，然后拖动，图标随着鼠标移动；这个效果的实现依赖控件的三个事件：Mouse_Down,Mouse_Move,Mouse_Up
- 首先在Mouse_Down事件设置”拖动”标志，表明鼠标已经按下，将要移动；同时记录鼠标的起始位置
- 然后在Mouse_Move事件计算鼠标的新位置，将图标设置到鼠标的位置，重新绘图
- 最后在Mouse_Up事件关闭”拖动”标志，标志鼠标已经弹起
实现如下：
首先，在Visual Studio 2010创建一个“Windows窗体应用程序”项目，在Form上任意拖入一个控件（比如Button，Label等，为了看得明白，我这里拖入的是PictureBox控件），为PictureBox的Image属性设置图片，效果如下:
然后修改Form对应的代码：
首先为Form增加两个实例变量，分别为拖动标识和PictureBox控件的位置
View Code
#region Fields private Boolean m_bDragFlag = false; private Point m_oStartLocation; #endregion
#region Fields private Boolean m_bDragFlag = false; private Point m_oStartLocation; #endregion
然后为PictureBox控件实现Mouse_Down,Mouse_Move,Mouse_Up事件
View Code
#region Events //PictureBox.Click事件 private void pbxDrag_Click(object sender, EventArgs e) { //0.取控件实例 var pbxDrag = sender as PictureBox; //1.用边框模拟选中状态 pbxDrag.BorderStyle = BorderStyle.FixedSingle; } //PictrueBox.MouseDown事件(鼠标在控件上按下左键触发) private void pbxDrag_MouseDown(object sender, MouseEventArgs e) { //0.取控件实例 var pbxDrag = sender as PictureBox; //1.设置"拖动"标识 this.m_bDragFlag = true; //2.设置鼠标形状 this.Cursor = Cursors.SizeAll; //3.设置初始位置 this.m_oStartLocation = pbxDrag.Location; } //PictureBox.MouseMove事件(鼠标在控件上移动后触发) private void pbxDrag_MouseMove(object sender, MouseEventArgs e) { //0.取控件实例 var pbxDrag = sender as PictureBox; if (this.m_bDragFlag) { //1.设置鼠标形状 this.Cursor = Cursors.Default; //2.设置控件新位置 pbxDrag.Location = new Point(this.m_oStartLocation.X + e.X, this.m_oStartLocation.Y + e.Y); //3.重新绘制图形 this.Invalidate(); this.Update(); //4.修正位置 this.m_oStartLocation = pbxDrag.Location; } } //PictureBox.MouseUp事件(鼠标在控件上弹起时触发) private void pbxDrag_MouseUp(object sender, MouseEventArgs e) { //0.设置鼠标形状 this.Cursor = Cursors.Default; //1.设置"拖动"标识 this.m_bDragFlag = false; } #endregion
#region Events //PictureBox.Click事件 private void pbxDrag_Click(object sender, EventArgs e) { //0.取控件实例 var pbxDrag = sender as PictureBox; //1.用边框模拟选中状态 pbxDrag.BorderStyle = BorderStyle.FixedSingle; } //PictrueBox.MouseDown事件(鼠标在控件上按下左键触发) private void pbxDrag_MouseDown(object sender, MouseEventArgs e) { //0.取控件实例 var pbxDrag = sender as PictureBox; //1.设置"拖动"标识 this.m_bDragFlag = true; //2.设置鼠标形状 this.Cursor = Cursors.SizeAll; //3.设置初始位置 this.m_oStartLocation = pbxDrag.Location; } //PictureBox.MouseMove事件(鼠标在控件上移动后触发) private void pbxDrag_MouseMove(object sender, MouseEventArgs e) { //0.取控件实例 var pbxDrag = sender as PictureBox; if (this.m_bDragFlag) { //1.设置鼠标形状 this.Cursor = Cursors.Default; //2.设置控件新位置 pbxDrag.Location = new Point(this.m_oStartLocation.X + e.X, this.m_oStartLocation.Y + e.Y); //3.重新绘制图形 this.Invalidate(); this.Update(); //4.修正位置 this.m_oStartLocation = pbxDrag.Location; } } //PictureBox.MouseUp事件(鼠标在控件上弹起时触发) private void pbxDrag_MouseUp(object sender, MouseEventArgs e) { //0.设置鼠标形状 this.Cursor = Cursors.Default; //1.设置"拖动"标识 this.m_bDragFlag = false; } #endregion