配置文件

// 1. QMetaObject::connectSlotsByName
void Widget::on_btnOpen_clicked()
{
    QString conf_path = qApp -> applicationDirPath() + "/conf/settings.ini";
    std::unique_ptr<QSettings> iniSet(new QSettings(conf_path, QSettings::IniFormat));  //2. 操作ini
    QString lastPath = iniSet -> value("/LastPath/path/").toString();   //读ini
    if(lastPath.isEmpty())
    {
        lastPath = QStandardPaths::writableLocation(QStandardPaths::PicturesLocation);  //3. 标准设备,默认路径
    }
    QString fileName = QFileDialog::getOpenFileName(this, "请选择", lastPath, "图片(*.png *.img *.gif);(*.*);");
    if(fileName.isEmpty() || fileName.isNull())  return;

    int end =fileName.lastIndexOf("/");
    QString _path = fileName.left(end);
    iniSet -> setValue("/LastPath/path/", _path);           //写ini, 保存上次路径

    std::unique_ptr<QPixmap> pix(new QPixmap(fileName));
    pix -> scaled( ui->label_img->size(), Qt::KeepAspectRatio);     //4. 缩放|抗锯齿
    ui -> label_img ->setScaledContents(true);                      //自适应显示
    ui -> lineEdit_path -> setText(fileName);
    ui -> label_img -> setPixmap( *pix );
}