C++ QT图片查看器

private:
    

    QList<QString> fs;
    int i;



void MainWindow::on_btnSlt_clicked()
{
    QStringList files = QFileDialog::getOpenFileNames(this,"选择图片",".","Images(*.png *.jpg *.bmp)");
    qDebug()<<files;
    ui->picList->clear();
    ui->picList->appendPlainText(files.join("\n"));
    fs = files;
    ui->labelPic->setPixmap(QPixmap(fs[0]));
}

void MainWindow::on_btnPs_clicked()
{
    i--;
    if(i<0){
        i = 0;
    }
    ui->labelPic->setPixmap(QPixmap(fs[i]));
}

void MainWindow::on_btnNt_clicked()
{
    i++;
    if(i == fs.length()){
        i = fs.length()-1;
    }
    ui->labelPic->setPixmap(QPixmap(fs[i]));
}