Image 鼠標拖拽與鼠標中鍵的縮放

1、Image在窗體上拖拽，勢必會用到鼠標的三個事件(MouseDown，MouseUp，MouseMove)，以左鍵爲例，PictureBox爲載體

        Point mouseDownPoint = new Point(); //記錄拖拽過程鼠標位置
        bool isMove = false;    //判斷鼠標在picturebox上移動時，是否處於拖拽過程(鼠標左鍵是否按下)
       private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
                isMove = true;
            }
        }
        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            pictureBox1.Dock = DockStyle.None;
            if (e.Button == MouseButtons.Left)
            {
                isMove = false;
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            
            if (isMove)
            {
                int x, y;
                int moveX, moveY;
                moveX = Cursor.Position.X - mouseDownPoint.X;
                moveY = Cursor.Position.Y - mouseDownPoint.Y;
                x = pictureBox1.Location.X + moveX;
                y = pictureBox1.Location.Y + moveY;
                pictureBox1.Location = new Point(x, y);
                mouseDownPoint.X = Cursor.Position.X;
                mouseDownPoint.Y = Cursor.Position.Y;
            }
        }

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2、(1)鼠標滾輪------Image縮放(實現思路，靠設置PictureBox裏SizeModel屬性爲Zoom,改變PictureBox大小進行放縮，大圖片有卡頓，慢等問題，後續優化)

         Bitmap myBmp;
         int zoomStep = 40;      //縮放步長
        //窗體加載事件
        private void Form_Load(object sender, EventArgs e)
        {
             string filename = "圖片路徑+文件名(包括擴展名)"
             myBmp = new Bitmap(filename);//多種重載，基於本身的方式，將Image賦值與畫布
             pictureBox1.Image = myBmp;
             pictureBox1.SizeMode = PictureBoxSizeMode.Zoom; //設置picturebox爲縮放模式
         }
       //PictureBox控件綁定上鼠標中鍵事件
       private void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            int x = e.Location.X;
            int y = e.Location.Y;
            int ow = pictureBox1.Width;
            int oh = pictureBox1.Height;
            int VX, VY;
            if (e.Delta > 0)
            {
                pictureBox1.Width += zoomStep;
                pictureBox1.Height += zoomStep;

                PropertyInfo pInfo = pictureBox1.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                                                                                         BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pictureBox1, null);

                pictureBox1.Width = rect.Width;
                pictureBox1.Height = rect.Height;
            }
            if (e.Delta < 0)
            {

                if (pictureBox1.Width < myBmp.Width / 10)
                    return;

                pictureBox1.Width -= zoomStep;
                pictureBox1.Height -= zoomStep;
                PropertyInfo pInfo = pictureBox1.GetType().GetProperty("ImageRectangle", BindingFlags.Instance |
                                                                                         BindingFlags.NonPublic);
                Rectangle rect = (Rectangle)pInfo.GetValue(pictureBox1, null);
                pictureBox1.Width = rect.Width;
                pictureBox1.Height = rect.Height;
            }

            VX = (int)((double)x * (ow - pictureBox1.Width) / ow);
            VY = (int)((double)y * (oh - pictureBox1.Height) / oh);
            pictureBox1.Location = new Point(pictureBox1.Location.X + VX, pictureBox1.Location.Y + VY);
        }

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