图片压缩之二（.net实现）

/// <summary>
    /// 生成缩略图(自动计算宽高)
    /// </summary>
    /// <param name="originalImagePath">源图路径（物理路径）</param>
    /// <param name="thumbnailPath">缩略图保存路径（物理路径）</param>
    /// <param name="width">缩略图宽度</param>
    /// <param name="height">缩略图高度</param>
    /// <param name="height">是否删除原图</param> 
    public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height,bool isDeleteoriginalImage)
    {
        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

        int towidth = width;
        int toheight = height;

        int x = 0;
        int y = 0;
        int ow = originalImage.Width;       //源图片宽
        int oh = originalImage.Height;      //源图片高

        if (towidth >= ow && toheight >= oh)     //如果源图片等于或小于要生成图片的大小,则直接复制
        {
            File.Copy(originalImagePath, thumbnailPath);
            if (isDeleteoriginalImage)
            {
                File.Delete(originalImagePath);
            }
            originalImage.Dispose();
            return;
        }

        double wh = towidth / toheight;
        double owh = ow / oh;
        
        //按等比宽计算生成图片的宽高
        toheight = oh * towidth / ow;       //得到按宽等比的高


        if (toheight > height) //如果等比的高还是大于生成缩略图的高
        {
            towidth = towidth * height / toheight;
            toheight = height;
        }

        //新建一个bmp图片
        System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

        //新建一个画板
        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

        //设置高质量插值法
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

        //设置高质量,低速度呈现平滑程度
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

      

        //清空画布并以透明背景色填充
        g.Clear(System.Drawing.Color.Transparent);

        //在指定位置并且按指定大小绘制原图片的指定部分
        g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
            new System.Drawing.Rectangle(x, y, ow, oh),
            System.Drawing.GraphicsUnit.Pixel);

        //开始定义打水印
        System.Drawing.Font f = new System.Drawing.Font("Verdana", 16);
        System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);
        g.DrawString("点起床啊\r\nsfzdsfdsfdsfsdfdsfdsf111", f, b, 15, 15);


        try
        {
            //以jpg格式保存缩略图
            bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
        catch (System.Exception e)
        {
            throw e;
        }
        finally
        {
            originalImage.Dispose();
            bitmap.Dispose();
            g.Dispose();
        }
    }