1 getSaveFileName

//保存文件按钮对应的槽函数
void Widget::on_save_btn_clicked()
{//调用QFileDialog的静态成员函数getSaveFileName来获取选中的文件路径QString fileName = QFileDialog::getSaveFileName(this,"保存文件","./","Image File(*.png *.jpg *.bmp);;Text File(*.txt);;ALL(*.*)");if(fileName.isNull()){QMessageBox::information(this,"提示","您取消了选择文件");}qDebug() << fileName;//1、实例化一个文件对象QFile file_w(fileName);//、2向文件中写入内容//获取文本编辑器中的文本内容 toPlainText()  返回字符串QString msg = ui->textEdit->toPlainText();file_w.write(msg.toLocal8Bit());  //toLocal8Bit()将字符串转换为字符数组//3、关闭文件对象file_w.close();
}

2、键盘事件的上下左右操作

void Widget::keyPressEvent(QKeyEvent *Event)
{//qDebug()<<"键盘被按下了"<<Event->text()<<"键值为"<<Event->key();switch(Event->key()){//上移case 'W':{if(ui->label->y()<=0-ui->label->height()){ui->label->move(ui->label->x(),this->height());}ui->label->move(ui->label->x(),ui->label->y()-5);}break;//下移case 'S':{if(ui->label->y()>=this->height()){ui->label->move(ui->label->x(),0-ui->label->height());}ui->label->move(ui->label->x(),ui->label->y()+5);}break;//左移case 'A':{if(ui->label->x()<=0-ui->label->width()){ui->label->move(this->width(),ui->label->y());}ui->label->move(ui->label->x()-5,ui->label->y());}break;//右移case 'D':{if(ui->label->x()>=this->width()){ui->label->move(0-ui->label->width(),ui->label->y());}ui->label->move(ui->label->x()+5,ui->label->y());}break;}
}

3 思维导图