将枚举TagLib :: ID3v2 :: AttachedPictureFrame :: Type转换为字符串？

问题描述

我正在使用用于c ++的taglib。如果我使用以下代码：

ID3v2::AttachedPictureFrame::Type t = picFrame->type();

例如，我得到“ FrontCover（3）”，但是我没有找到任何解决方案将其转换为字符串以保存值。

我还需要一个解决方案，如何设置ID3v2::AttachedPictureFrame::Type t并将其写入APIC标签。

解决方法

TagLib::ID3v2::AttachedPictureFrame的文档指出Type是该类中定义的枚举：

enum      Type {
  Other = 0x00,FileIcon = 0x01,OtherFileIcon = 0x02,FrontCover = 0x03,BackCover = 0x04,LeafletPage = 0x05,Media = 0x06,LeadArtist = 0x07,Artist = 0x08,Conductor = 0x09,Band = 0x0A,Composer = 0x0B,Lyricist = 0x0C,RecordingLocation = 0x0D,DuringRecording = 0x0E,DuringPerformance = 0x0F,MovieScreenCapture = 0x10,ColouredFish = 0x11,Illustration = 0x12,BandLogo = 0x13,PublisherLogo = 0x14
}

没有自动转换可以将enum的符号转换为std::string，反之亦然。另外，您已经注意到TagLib::ID3v2::AttachedPictureFrame类没有提供这种功能。
您需要为此实现辅助功能：

std::string attachedPictureFrameType2String(AttachedPictureFrame::Type type) {
    switch(type) {
    case AttachedPictureFrame::Other: return "Other";
    case AttachedPictureFrame::FileIcon: return "FileIcon";
    case AttachedPictureFrame::OtherFileIcon: return "OtherFileIcon";
    case AttachedPictureFrame::FrontCover: return "FrontCover";
    // All the other enum values ...
    }
}

AttachedPictureFrame::Type string2AttachedPictureFrameType(const std::string& s) {
    if(s == "Other") return AttachedPictureFrame::Other;
    if(s == "FileIcon") return AttachedPictureFrame::FileIcon;
    if(s == "OtherFileIcon") return AttachedPictureFrame::OtherFileIcon;
    if(s == "FrontCover") return AttachedPictureFrame::FrontCover;
    // All the other valid string values ...
    throw std::exception("Invalid string");
}

---

@Uriya Harpeness在其comment中提到，也可以使用字典来做到这一点，例如：

 using std::pair<AttachedPictureFrame::Type,std::string> = TypeDictItem;
 using std::vector<TypeDictItem> = TypeDict;
 const TypeDict pictureFrameTypeDict = { 
       std::make_pair(AttachedPictureFrame::Other,"Other"),std::make_pair(AttachedPictureFrame::FileIcon,"FileIcon"),std::make_pair(AttachedPictureFrame::OtherFileIcon,"OtherFileIcon"),std::make_pair(AttachedPictureFrame::FrontCover,"FrontCover")
     // ...
 };

 std::string attachedPictureFrameType2String(AttachedPictureFrame::Type type) {
     auto found = std::find_if(std::begin(pictureFrameTypeDict),std::end(pictureFrameTypeDict),[type](const TypeDictItem& i) { return i.first == type; } );
     if(found != pictureFrameTypeDict.end()) {
          return (*found).second;
     }
     throw std::exception("Unexpected enum value.");
 }

 AttachedPictureFrame::Type string2AttachedPictureFrameType(const std::string s) {
     auto found = std::find_if(std::begin(pictureFrameTypeDict),[s](const TypeDictItem& i) { return i.second == s; } );
     if(found != pictureFrameTypeDict.end()) {
          return (*found).first;
     }
     throw std::exception("Invalid string.");
 }