windows – 使用Win32 API查找图标资源中的图标数量

按照ICO文件格式(由图标目录和实际图标图像组成),图标资源也包含两部分：RT_GROUP_ICON类型的图标目录和各个图标(RT_ICON).该目录由以下结构表示：

#pragma pack( push )
#pragma pack( 2 )
typedef struct 
{
    WORD            idReserved;   // Reserved (must be 0)
    WORD            idType;       // Resource type (1 for icons)
    WORD            idCount;      // How many images?
    GRPICONDIRENTRY idEntries[1]; // The entries for each image
} GRPICONDIR,*LPGRPICONDIR;
#pragma pack( pop )

和

#pragma pack( push )
#pragma pack( 2 )
typedef struct
{
    BYTE   bWidth;               // Width,in pixels,of the image
    BYTE   bHeight;              // Height,of the image
    BYTE   bColorCount;          // Number of colors in image (0 if >=8bpp)
    BYTE   bReserved;            // Reserved
    WORD   wPlanes;              // Color Planes
    WORD   wBitCount;            // Bits per pixel
    DWORD  dwBytesInRes;         // how many bytes in this resource?
    WORD   nID;                  // the ID
} GRPICONDIRENTRY,*LPGRPICONDIRENTRY;
#pragma pack( pop )

可以使用以下代码检索图标组ID的图标目录：

typedef std::list<GRPICONDIRENTRY> IconDirectory;

IconDirectory GetIconDirectory( HMODULE hMod,WORD Id ) {
    HRSRC hRsrc = FindResourceW( hMod,MAKEINTRESOURCE( Id ),RT_GROUP_ICON );
    HGLOBAL hGlobal = LoadResource( hMod,hRsrc );
    GRPICONDIR* lpGrpIconDir = (GRPICONDIR*)LockResource( hGlobal );

    IconDirectory dir;
    for ( size_t i = 0; i < lpGrpIconDir->idCount; ++i ) {
        dir.push_back( lpGrpIconDir->idEntries[ i ] );
    }
    return dir;
}

使用图标目录中的信息,可以使用以下代码构建各个图标：

HICON LoadSpecificIcon( HMODULE hMod,RT_ICON );
    HGLOBAL hGlobal = LoadResource( hMod,hRsrc );
    BYTE* lpData = (BYTE*)LockResource( hGlobal );
    DWORD dwSize = SizeofResource( hMod,hRsrc );

    HICON hIcon = CreateIconFromResourceEx( lpData,dwSize,TRUE,0x00030000,LR_DEFAULTCOLOR );
    return hIcon;
}

将所有部分放在一起,以下将explorer.exe作为资源文件加载,检索ID为101的第一个图标组,并从每个条目的图标目录中打印信息.然后它创建单个图标并输出xHotspot和yHotspot数据.对于图标,热点位于中心：

void PrintIconDirEntry( const GRPICONDIRENTRY& DirEntry ) {
    _wprintf_p( L"ID: %04d; width=%02d; height=%02d; bpp=%02dn",DirEntry.nID,DirEntry.bWidth,DirEntry.bHeight,DirEntry.wBitCount );
}

void PrintIconInfo( HICON hIcon ) {
    ICONINFO ii = { 0 };
    GetIconInfo( hIcon,&ii );
    _wprintf_p( L"xHotspot=%02d; yHotspot=%02dn",ii.xHotspot,ii.yHotspot );
}

typedef std::list<GRPICONDIRENTRY>::const_iterator IconDirectoryCIt;

int _tmain(int argc,_TCHAR* argv[])
{
    HMODULE hMod = LoadLibraryExW( L"C:Windowssystem32explorer.exe",NULL,LOAD_LIBRARY_AS_IMAGE_RESOURCE );
    IconDirectory dir = GetIconDirectory( hMod,101 );
    for ( IconDirectoryCIt it = dir.begin(); it != dir.end(); ++it ) {
        PrintIconDirEntry( *it );
        HICON hIcon = LoadSpecificIcon( hMod,it->nID );
        PrintIconInfo( hIcon );
        DestroyIcon( hIcon );
    }
    return 0;
}

总结一下：检索图标资源的所有图标大小和颜色变化包括两个步骤：

>检索图标目录,其中包含图标组中所有图标的信息.
>迭代图标目录并使用CreateIconFromResourceEx构建单个图标.

参考文献：

>图标格式的MSDN文档：Icons
>旧的新事物：The evolution of the ICO file format,part 1: Monochrome beginnings
>旧的新事物：The evolution of the ICO file format,part 2: Now in color!
>旧的新事物：The evolution of the ICO file format,part 3: Alpha-blended images
>旧的新事物：The evolution of the ICO file format,part 4: PNG images
>旧的新事物：The format of icon resources
>旧的新事物：How do I override the default icon selection algorithm?