PictureBox中的图片实现鼠标滑轮控制缩放和平移

昨天刚学会了如何实现PictureBox控件中的图像自动缩放和平移，下面我把过程给大家说一下：

参考了：https://www.cnblogs.com/jinqier/p/3497201.html

1、首先要拖一个控件，Panel控件作为容器

2、然后父容器里面拖一个PictureBox控件，设置属性为“”停靠在父容器“”

pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;
pictureBox1.Dock = DockStyle.None;

 3‘设置背景色了。Panel 和PictureBox的背景色要设置成一样的，我这里设置的都是为Blue;

4、为PictureBox添加事件了，下面是代码

 public System.Drawing.Point mouseDownPoint;//存储鼠标焦点的全局变量
        public bool isSelected = false;
        private void Form1_Load(object sender, EventArgs e)
        {
            pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;
            pictureBox1.Dock = DockStyle.None;
          
        }
　　　　　　//这个事件是鼠标滑轮滚动的触发事件，可以在Designer.cs中注册。
　　　　　　this.pictureBox1.MouseWheel += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseWheel);
　　　　　　this.pictureBox1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseDown);
　　　　　　this.pictureBox1.MouseEnter += new System.EventHandler(this.pictureBox1_MouseEnter);
　　　　　　this.pictureBox1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseMove);
　　　　　　this.pictureBox1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.pictureBox1_MouseUp);
　　　　　　　　　
        private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            double scale = 1;
            if (pictureBox1.Height > 0)
            {
                scale = (double)pictureBox1.Width / (double)pictureBox1.Height;
            }
            pictureBox1.Width += (int)(e.Delta * scale);
            pictureBox1.Height += e.Delta;
        }
        private void pictureBox1_MouseEnter(object sender, EventArgs e)
        {
            pictureBox1.Focus();
            pictureBox1.Cursor = Cursors.SizeAll;
        }

        //在MouseDown处获知鼠标是否按下，并记录下此时的鼠标坐标值；
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mouseDownPoint.X = Cursor.Position.X;  //注：全局变量mouseDownPoint前面已定义为Point类型  
                mouseDownPoint.Y = Cursor.Position.Y;
                isSelected = true;
            }
        }

        //在MouseUp处获知鼠标是否松开，终止拖动操作；
        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            isSelected = false;

        }

        private bool IsMouseInPanel()
        {
            if (this.panel_Picture.Left < PointToClient(Cursor.Position).X
                    && PointToClient(Cursor.Position).X < this.panel_Picture.Left
                    + this.panel_Picture.Width && this.panel_Picture.Top
                    < PointToClient(Cursor.Position).Y && PointToClient(Cursor.Position).Y
                    < this.panel_Picture.Top + this.panel_Picture.Height)
            {
                return true;
            }
            else
            {
                return false;
            }       
        }

        //图片平移,在MouseMove处添加拖动函数操作
        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (isSelected && IsMouseInPanel())//确定已经激发MouseDown事件，和鼠标在picturebox的范围内
            {
                this.pictureBox1.Left = this.pictureBox1.Left + (Cursor.Position.X - mouseDownPoint.X);
                this.pictureBox1.Top = this.pictureBox1.Top + (Cursor.Position.Y - mouseDownPoint.Y);
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
            }

        }

此方法实现的原理就是改变PictureBox的大小而改变图像的大小，平移也是。

这个比较简单的一种方法。