private void Form1_Load(object sender, EventArgs e)   
        {   
            //这句代码不会抱错，但是需要手动输入，.net编辑器无法自动识别AllowDrop   
            this.pictureBox1.AllowDrop = true;   
        }   
            
        private void pictureBox1_DragDrop(object sender, DragEventArgs e)   
        {   
            string fileName = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(0).ToString();   
            this.pictureBox1.Image = Image.FromFile(fileName);   
        }   
        private void pictureBox1_DragEnter(object sender, DragEventArgs e)   
        {   
            if (e.Data.GetDataPresent(DataFormats.FileDrop))   
                e.Effect = DragDropEffects.Link;   
            else e.Effect = DragDropEffects.None;   
        }