鼠标拖拽效果的实现

鼠标拖拽效果的实现

 

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

1. 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
2. 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
3. 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

#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

#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

 

 

 

分类: WinForm