C#图片放大缩小拖动

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#C# #图片 #放大 #缩小 #拖动

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本文介绍如何在C#中使用PictureBox控件实现图片的缩放和拖动功能。通过监听MouseWheel事件，实现鼠标滚轮控制图片的放大和缩小，并保持鼠标位置不变。同时，通过MouseDown和MouseMove事件，实现PictureBox内的图片拖动。

1.Panel里放picturebox，picturebox大小与panel相同。

放大缩小：

在窗体load事件中加入

this.MouseWheel += splitContainer1_Panel1_MouseWheel;（我用的是splitContainer，panel同理）

void splitContainer1_Panel1_MouseWheel(object sender, MouseEventArgs e)
        {
            Rectangle rectangle=new Rectangle();
            rectangle = splitContainer1.RectangleToClient(this.ClientRectangle);
            if (rectangle.Contains(MousePosition)) //判断鼠标位置是否在图片区域内
            {
                double step = 1.2;//缩放倍率
                if (e.Delta > 0)//放大
                {
                    if (pictureBox3.Height < Screen.PrimaryScreen.Bounds.Height * 4)
                    {
                        pictureBox3.Size = new Size((int)(pictureBox3.Width * step), (int)(pictureBox3.Height * step));//调整picturebox大小
                        int px_add = (int)(pictureBox3.PointToClient(MousePosition).X * (step - 1.0));
                        int py_add = (int)(pictureBox3.PointToClient(MousePosition).Y * (step - 1.0));
                        pictureBox3.Location = new Point(pictureBox3.Location.X - px_add, pictureBox3.Location.Y - py_add);//调整picturebox位置
                    }
                }
                else//缩小
                {
                    if (pictureBox3.Height > splitContainer1.Panel1.Height)
                    {
                        pictureBox3.Size = new Size((int)(pictureBox3.Width / step), (int)(pictureBox3.Height / step));
                        int px_add = (int)(pictureBox3.PointToClient(MousePosition).X * (1.0 - 1.0 / step));
                        int py_add = (int)(pictureBox3.PointToClient(MousePosition).Y * (1.0 - 1.0 / step));
                        pictureBox3.Location = new Point(pictureBox3.Location.X + px_add, pictureBox3.Location.Y + py_add);
                    }
                   
                }
            }

拖动图片

        Point mouseDownPoint = new Point();//鼠标按下时的坐标
        Boolean isSelected = false;
        private void pictureBox4_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;
            }
        }

        private void pictureBox4_MouseMove(object sender, MouseEventArgs e)
        {
            if (isSelected && IsMouseInPanel())//鼠标选中并且在panel内
            {
                this.pictureBox4.Left = this.pictureBox4.Left + (Cursor.Position.X - mouseDownPoint.X);
                this.pictureBox4.Top = this.pictureBox4.Top + (Cursor.Position.Y - mouseDownPoint.Y);
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
            }
        }