Qt之QImage无法获取图片尺寸（宽和高）

这个问题应该很多人都遇到过，比如下面这张图片test.png

    QImage image(":/test.png");
    qDebug()<<"current size:"<<image.width()<<image.height();
    QFileInfo fi(":/test.png");
    QString suffix=fi.suffix();
    qDebug()<<"current suffix:"<<suffix;

打印

current size: 0 0
current suffix: "png"

原因是图片的后缀可能被修改过，通过如下方法能正确获取到尺寸

QImage image(":/test.png");
    qDebug()<<"current size:"<<image.width()<<image.height();
    QFileInfo fi(":/test.png");
    QString suffix=fi.suffix();
    qDebug()<<"current suffix:"<<suffix;
    QString realSuffix=suffix;
    QMimeDatabase mimeDataBase;
    auto mimeType=mimeDataBase.mimeTypeForFile(fi,QMimeDatabase::MatchContent);
    QString mimeTypeName=mimeType.name();

    if(mimeTypeName=="image/jpg"||mimeTypeName=="image/jpeg"||mimeTypeName=="image/jpe")
    {
        if(!(suffix.contains("jpg",Qt::CaseInsensitive)||suffix.contains("jpeg",Qt::CaseInsensitive)||suffix.contains("jpe",Qt::CaseInsensitive)))
        {
            realSuffix="jpg";
            QImage image(":/test.png",realSuffix.toStdString().c_str());
            qDebug()<<"real size:"<<image.width()<<image.height();
            qDebug()<<"real suffix:"<<realSuffix;
        }
    }
    else if(mimeTypeName=="image/png")
    {
        if(!suffix.contains("png",Qt::CaseInsensitive))
        {
            realSuffix="png";
            QImage image(":/test.png",realSuffix.toStdString().c_str());
            qDebug()<<"real size:"<<image.width()<<image.height();
            qDebug()<<"real suffix:"<<realSuffix;
        }
    }

打印

current size: 0 0
current suffix: "png"
real size: 810 1080
real suffix: "jpg"