C# 文件拖拽和pixturBox缩放与拖拽功能

private void txtAppPath_DragEnter(object sender, System.Windows.Forms.DragEventArgs e)
    {
      if (e.Data.GetDataPresent(DataFormats.FileDrop))
      {
        e.Effect = DragDropEffects.Link;
      }
      else
      {
        e.Effect = DragDropEffects.None;
      }
    }
    private void txtAppPath_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
    {
      txtLocalFileName.Text = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(0).ToString();
    }

private void ScrewInfoForm_Shown(object sender, EventArgs e)
    {
      //加载装配图纸
      string drawingPath = Path.Combine(@"\\192.168.2.136\PCS", productCode + ".png");
      try
      {
        pbxDrawing.Load(drawingPath);
      }
      catch (Exception ex)
      {
        MessageBox.Show("加载装配图纸失败,详细:" + ex.Message, "测量", MessageBoxButtons.OK, MessageBoxIcon.Error);
        return;
      }
    }

pbxDrawing.MouseWheel += new MouseEventHandler(pbxDrawing_MouseWheel);
//实现滚轮缩放
    private void pbxDrawing_MouseWheel(object sender, System.Windows.Forms.MouseEventArgs e)
    {
      if (e.Delta < 0)
      {
        this.pbxDrawing.Width = this.pbxDrawing.Width * 9 / 10;
        this.pbxDrawing.Height = this.pbxDrawing.Height * 9 / 10;
      }
      else
      {
        this.pbxDrawing.Width = this.pbxDrawing.Width * 11 / 10;
        this.pbxDrawing.Height = this.pbxDrawing.Height * 11 / 10;
      }
    }

//实现移动图片
    int xPos;
    int yPos;
    bool MoveFlag;
    private void pbxDrawing_MouseDown(object sender, MouseEventArgs e)
    {
      this.pbxDrawing.Focus();
      MoveFlag = true;//已经按下.
      xPos = e.X;//当前x坐标.
      yPos = e.Y;//当前y坐标.
    }
    //在picturebox的鼠标按下事件里.
    private void pbxDrawing_MouseUp(object sender, MouseEventArgs e)
    {
      MoveFlag = false;
    }
    //在picturebox鼠标移动
    private void pbxDrawing_MouseMove(object sender, MouseEventArgs e)
    {
      if (MoveFlag)
      {
        pbxDrawing.Left += Convert.ToInt16(e.X - xPos);//设置x坐标.
        pbxDrawing.Top += Convert.ToInt16(e.Y - yPos);//设置y坐标.
      }
    }