QTday3

作业1：通过对话框实现保存文件

void burger::on_saveBtn_clicked()
{
    //调用函数，获取文件路径
    QString filename = QFileDialog::getSaveFileName(this,
                                                    "选择文件夹",
                                                    "./",
                                                    "Text File(*.txt)");
    if(filename.isNull())
    {
        QMessageBox::information(this,"提示","你取消了保存文件");
        return;
    }
 
    QString q = ui->textEdit->toPlainText();
    //实例化文件对象
    QFile file(filename);
    //判断文件是否正常打开
    if(!file.open(QFile::ReadWrite))
    {
        return;
    }
    QByteArray msg;
    msg.append(q);
    int a = file.write(msg);
    if(a == -1)
    {
        QMessageBox::warning(this,"警告","写入失败");
        return;
    }
    ui->textEdit->setText("");
    file.close();
}

作业2：

用键盘实现上下左右移动一个label

#include "burger.h"
#include "ui_burger.h"
 
burger::burger(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::burger)
{
    ui->setupUi(this);
    QPixmap p(":/112.jpg");
    ui->label->setPixmap(p);
    ui->label->setScaledContents(true);
 
}
 
burger::~burger()
{
    delete ui;
}
 
//键盘按下事件
void burger::keyPressEvent(QKeyEvent *event)
{
    switch (event->key()) {
        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;
        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;
        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;
        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;
    }
}
//键盘抬起事件
void burger::keyReleaseEvent(QKeyEvent *event)
{
 
}

思维导图：