asp.net 缩略图--源码--调试成功

private static Size NewSize(int maxWidth,int maxHeight,int Width,int Height)

{

double w=0.0;

double h=0.0;

double sw=Convert.ToDouble(Width);

double sh=Convert.ToDouble(Height);

double mw=Convert.ToDouble(maxWidth);

double mh=Convert.ToDouble(maxHeight);

if(sw<mw && sh<mh)//如果maxWidth和maxHeight大于源图像，则缩略图的长和高不变

{

w=sw;

h=sh;

}

else if((sw/sh)>(mw/mh))

{

w=maxWidth;

h=(w*sh)/sw;

}

else

{

h=maxHeight;

w=(h*sw)/sh;

}

return new Size(Convert.ToInt32(w),Convert.ToInt32(h));

}

public void SendSmallImage(string filename,string newfile ,int maxHeight,int maxWidth)

{

System.Drawing.Image img=System.Drawing.Image.FromFile(filename);//源图像的信息

System.Drawing.Imaging.ImageFormat thisformat=img.RawFormat; //源图像的格式

Size newSize=NewSize(maxWidth,maxHeight,img.Width,img.Height); //返回调整后的图像Width与Height

Bitmap outBmp=new Bitmap(newSize.Width,newSize.Height);

Graphics g=Graphics.FromImage(outBmp);

//设置画布的描绘质量

g.CompositingQuality =CompositingQuality.HighQuality;

g.SmoothingMode=SmoothingMode.HighQuality;

g.InterpolationMode=InterpolationMode.HighQualityBicubic;

g.DrawImage(img,new Rectangle(0,0,newSize.Width,newSize.Height),0,0,img.Width,img.Height,GraphicsUnit.Pixel);

g.Dispose();

//以下代码为保存图片时，设置压缩质量

EncoderParameters encoderParams=new EncoderParameters();

long[] quality=new long[1];

quality[0]=100;

EncoderParameter encoderParam= new EncoderParameter(System.Drawing.Imaging.Encoder.Quality,quality);

encoderParams.Param[0]=encoderParam;

//获取包含有关内置图像编码解码器的信息的ImageCodecInfo对象。

ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();

ImageCodecInfo jpegICI=null;

for(int x=0;x<arrayICI.Length;x++)

{

if(arrayICI[x].FormatDescription.Equals("JPEG"))

{

jpegICI=arrayICI[x];//设置jpeg编码

break;

}

}

if(jpegICI!=null)

{

outBmp.Save(newfile,jpegICI,encoderParams);

}

else

{

outBmp.Save(newfile,thisformat);

}

img.Dispose();

outBmp.Dispose();

}