使用C#编写的轻量级图片库

private const int WM_SYSCOMMAND = 0x0112;
private const int SC_MOVE = 0xF010;/*移动信息*/ 
/*表示鼠标在窗口标题栏时的系统信息*/
private const int HTCAPTION = 0x0002;
[DllImport("user32.dll")] 
public static extern bool SendMessage(IntPtr hwnd, int wMsg, int wParam, int lParam);
[DllImport("user32.dll")] 
public static extern bool ReleaseCapture(); 
/*响应鼠标单击事件*/
private void Form1_MouseDown(object sender, MouseEventArgs e) 
{ 
	/*鼠标相对于窗体的坐标*/
	if (e.Location.Y <= 36) {
		ReleaseCapture();
		SendMessage(this.Handle, WM_SYSCOMMAND, SC_MOVE + HTCAPTION, 0); 
	} 
}

    private Image dealPic(String picPath) {
    	Image pictrue = Image.FromFile(picPath);
    	int tmpW = PIC_WIDTH, tmpH = PIC_HEIGHT;
    	/*PIC_WIDTH为外框的限制宽度,PIC_HEIGHT为外框的限制高度,为全局变量*/
    	double rate;//缩放比例
    	int width = pictrue.Size.Width;
    	int height = pictrue.Size.Height;
    	size = pictrue.Size;
    	/*图像裁剪处理*/
    	if (width > PIC_WIDTH || height > PIC_HEIGHT)
    	{
    		if ((double)(width * 1.0 / height) < 1.5)//过高
    		{
    			rate = height * 1.0 / tmpH;
    			tmpW = (int)(width * 1.0 / rate);
    		}
    		else//过宽
    		{
    			rate = width * 1.0 / tmpW;
    			tmpH = (int)(height * 1.0 / rate);
    		}
    	} else
     	return pictrue;
    	Image newPic = pictrue.GetThumbnailImage(tmpW, tmpH, null, IntPtr.Zero);//绘制底质量图 
    	/*释放图片内存*/
    	pictrue.Dispose();
    	return newPic;
    }