C++实现读取图片长度和宽度
看到一个用ASP写的读取图片文件的长度、宽度的程序，感觉有点意思，于是用C++也写了一个。
#include<iostream>
#include<fstream>
#include<string>
usingnamespacestd;
classCImage
{
private:
longm_Width;
longm_Height;
intget_extension(stringfname);
public:
CImage()
{
m_Width=0;
m_Height=0;
};
voidLoadImage(char*fname);
longget_width()
{
returnm_Width;
};
longget_height()
{
returnm_Height;
};
};
intCImage::get_extension(stringfname)
{
charc=fname.at(fname.length()-1);
charc2=fname.at(fname.length()-3);
if((c=='f')&&(c2=='g')){//fileextensionnameisgif
return1;
}elseif((c=='g')&&(c2=='j')){//fileextensionnameisjpg
return2;
}elseif((c=='g')&&(c2=='p')){//fileextensionnameispng
return3;
}elseif((c=='p')&&(c2=='b')){//fileextensionnameisbmp
return4;
}
return0;
}
voidCImage::LoadImage(char*fname)
{
m_Width=m_Height=0;
ifstreamffin(fname,std::ios::binary);
if(!ffin){
cout<<"Cannotopenthisfile."<<endl;
return;
}
intresult=get_extension(fname);
chars1[2]={0},s2[2]={0};
switch(result)
{
case1://gif
ffin.seekg(6);
ffin.read(s1,2);
ffin.read(s2,2);
m_Width=(unsignedint)(s1[1])<<8|(unsignedint)(s1[0]);
m_Height=(unsignedint)(s2[1])<<8|(unsignedint)(s2[0]);
break;
case2://jpg
ffin.seekg(164);
ffin.read(s1,2);
ffin.read(s2,2);
m_Width=(unsignedint)(s1[1])<<8|(unsignedint)(s1[0]);
m_Height=(unsignedint)(s2[1])<<8|(unsignedint)(s2[0]);
break;
case3://png
ffin.seekg(17);
ffin.read(s1,2);
ffin.seekg(2,std::ios::cur);
ffin.read(s2,2);
m_Width=(unsignedint)(s1[1])<<8|(unsignedint)(s1[0]);
m_Height=(unsignedint)(s2[1])<<8|(unsignedint)(s2[0]);
break;
case4://bmp
ffin.seekg(18);
ffin.read(s1,2);
ffin.seekg(2,std::ios::cur);
ffin.read(s2,2);
m_Width=(unsignedint)(s1[1])<<8|(unsignedint)(s1[0]);
m_Height=(unsignedint)(s2[1])<<8|(unsignedint)(s2[0]);
break;
default:
cout<<"NO"<<endl;
break;
}
ffin.close();
};
intmain(intargc,char*argv[])
{
if(argc<2){
printf("usage:programimagefilename/n");
return0;
}
CImagetest;
test.LoadImage(argv[1]);
cout<<"width:"<<test.get_width()<<endl;
cout<<"height:"<<test.get_height()<<endl;
return0;
}