上传图片并且生成可以控制大小图片清晰度的方法

 

public static string ReSizeImge(string filePath,string text,int width,int height,int level)
{
    string fileName = System.IO.Path.GetFileName(filePath).ToLower();
    string fileExtension = System.IO.Path.GetExtension(filePath).ToLower();
    string document = System.IO.Path.GetDirectoryName(filePath)+"\\";
    bool check = false;
    switch(fileExtension)
    {
        case ".jpg":check =true;
            break;
        case ".gif":check =false;
            break;
        default: check =false;
            break;
    }

    //图片按比例缩放算法
    if(check)
    {
        string saveName = Guid.NewGuid().ToString().Replace("-","")+fileExtension;
        System.Drawing.Image oldimage = System.Drawing.Image.FromFile(filePath);

        double h=Convert.ToDouble(oldimage.Height.ToString());
        double w=Convert.ToDouble(oldimage.Width.ToString());
        double f=h/w;
        if(width==0&&height==0)
        {
            if(w>700){w=700;h=700*f;}
        }
        else if(width==0&&height!=0)
        {
            h = height;
            w = height*(1/f);
        }
        else if(width!=0&&height==0)
        {
            w = width;
            h = width*f;
        }
        else
        {
            w = width;
            h = height;
        }
        
        System.Drawing.Image thumbnailImage = oldimage.GetThumbnailImage(Convert.ToInt32(w),Convert.ToInt32(h),null,new System.IntPtr());
        Bitmap output=new Bitmap(thumbnailImage);

        //处理JPG质量的函数
        ImageCodecInfo[] codecs=ImageCodecInfo.GetImageEncoders(); 
        ImageCodecInfo ici=null;
        foreach(ImageCodecInfo codec in codecs){if(codec.MimeType=="image/jpeg")ici=codec;}
        EncoderParameters ep=new EncoderParameters();
        ep.Param[0]=new EncoderParameter(Encoder.Quality,(long)level);

        //Graphics g = Graphics.FromImage(output); 
        //g.DrawImage(thumbnailImage, 0, 0, thumbnailImage.Width, thumbnailImage.Height); 
        //Font f11 = new Font("Verdana", 9); 
        //Brush b = new SolidBrush(Color.White); 
        //g.DrawString(text, f11, b, 10, 10); 
        //g.Dispose(); 


        string Path = document+saveName;
        output.Save(Path,ici,ep);

        //释放所有使用对象
        ep.Dispose();
        output.Dispose();
        oldimage.Dispose();
        thumbnailImage.Dispose();

        //删除源图片
        UnitLink.Component.Common.doIO.DeletePath(filePath);
        return saveName;
    }
    else
    {
        return fileName;
    }
}