Qt QProcess stay_open example

[Rory]

It took me a little longer than it should have to develop this code to run ExifTool in stay_open mode within the Qt environment.  Any suggestions for further improvement are most welcome.

This function copies all the metadata from the source file list to the destination file list.

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int ExifTool::copyAll(const QStringList &src, QStringList &dst)
{
    // initial arguments to keep ExifTool open
    QStringList stayOpen;
    stayOpen << "-stay_open";
    stayOpen << "True";
    stayOpen << "-@";
    stayOpen << "-";

    // stdin stream with copy tags for each pair of files in the lists
    QByteArray args;
    for (int i = 0; i < src.length(); i++) {
        args += "-TagsFromFile\n";
        args += src.at(i) + "\n";       // src = path of source file
        args += "-all:all\n";
        args += dst.at(i) + "\n";       // dst = path of destination file
        args += "-execute\n";
    }
    // terminate stay_open
    args += "-stay_open\n";
    args += "False\n";

    QProcess et;
    et.start(exifToolPath, stayOpen);   // exifToolPath = path to ExifTool executable
    et.waitForStarted(3000);
    // write to stdin
    et.write(args);
    if (et.waitForFinished(30000)) { Put your success code here }
    else { Put your failure code here }
   
    return et.exitCode();               // return ExifTool exit code
}

[Phil Harvey]

You don't actually have to use -stay_open here since you are doing this synchronously and stopping the exiftool process afterward.  You could just as well do it more simply like this (but I can't test it out):

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int ExifTool::copyAll(const QStringList &src, QStringList &dst)
{
    // stdin stream with copy tags for each pair of files in the lists
    QStringList args;
    for (int i = 0; i < src.length(); i++) {
        args << "-TagsFromFile";
        args << src.at(i);       // src = path of source file
        args << "-all:all";
        args << dst.at(i);       // dst = path of destination file
        args << "-execute";
    }

    QProcess et;
    et.start(exifToolPath, args);       // exifToolPath = path to ExifTool executable
    return et.exitCode();               // return ExifTool exit code
}

- Phil

[Rory]

Yes, that makes total sense. Thanks Phil.