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  • 压缩图片

    /// <summary>
    /// 图像无损压缩
    /// </summary>
    /// <param name="sFile">源文件</param>
    /// <param name="dFile">目标文件</param>
    /// <param name="dHeight">压缩后的高度</param>
    /// <param name="dWidth">压缩后的宽度</param>
    /// <param name="scale">压缩比</param>
    /// <param name="flag">压缩质量参数,一般可设50</param>
    /// <returns></returns>
    public static bool GetPicThumbnail(string sFile, string dFile, int dHeight, int dWidth, float scale, int flag)
    {
    System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile);
    ImageFormat tFormat = iSource.RawFormat;
    int sW = 0, sH = 0;
    //按比例缩放
    Size tem_size = new Size(iSource.Width, iSource.Height);

    if (dHeight == 0 && dWidth == 0 && scale != 0)
    {
    dHeight = Convert.ToInt32(scale * iSource.Height);
    dWidth = Convert.ToInt32(scale * iSource.Width);
    }
    if (tem_size.Width > dHeight || tem_size.Width > dWidth)
    {
    if ((tem_size.Width * dHeight) > (tem_size.Height * dWidth))
    {
    sW = dWidth;
    sH = (dWidth * tem_size.Height) / tem_size.Width;
    }
    else
    {
    sH = dHeight;
    sW = (tem_size.Width * dHeight) / tem_size.Height;
    }
    }
    else
    {
    sW = tem_size.Width;
    sH = tem_size.Height;
    }
    Bitmap ob = new Bitmap(dWidth, dHeight);
    Graphics g = Graphics.FromImage(ob);
    g.Clear(Color.WhiteSmoke);
    g.CompositingQuality = CompositingQuality.HighQuality;
    g.SmoothingMode = SmoothingMode.HighQuality;
    g.InterpolationMode = InterpolationMode.HighQualityBicubic;
    g.DrawImage(iSource, new System.Drawing.Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
    g.Dispose();

    //以下代码为保存图片时,设置压缩质量
    EncoderParameters ep = new EncoderParameters();
    long[] qy = new long[1];
    qy[0] = flag;//设置压缩的比例1-100
    EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
    ep.Param[0] = eParam;

    try
    {
    ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
    ImageCodecInfo jpegICIinfo = null;
    for (int x = 0; x < arrayICI.Length; x++)
    {
    if (arrayICI[x].FormatDescription.Equals("JPEG"))
    {
    jpegICIinfo = arrayICI[x];
    break;
    }
    }

    if (jpegICIinfo != null)
    {
    ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
    }
    else
    {
    ob.Save(dFile, tFormat);
    }
    return true;
    }
    catch
    {
    return false;
    }
    finally
    {
    iSource.Dispose();
    ob.Dispose();
    }
    }

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  • 原文地址:https://www.cnblogs.com/jiangcm/p/9297911.html
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