Qt小部件基础教程（四）:记事本源文件项目代码

此为一个系列的关于qt小部件的入门教程，在本主题中，我们通过使用C ++和Qt Widgets模块实现一个简单的记事本应用程序来教授基本的Qt知识。

Qt是目前最先进、最完整的跨平台C++开发工具。它不仅完全实现了一次编写，所有平台无差别运行，更提供了几乎所有开发过程中需要用到的工具。如今，Qt已被运用于超过70个行业、数千家企业，支持数百万设备及应用。

Qt最新试用版

向导为Notepad类生成的源文件如下所示：

#include "notepad.h" "notepad.h"#include "ui_notepad.h" "ui_notepad.h"NotepadNotepad::Notepad((QWidget *parent) :    ) :    QMainWindow(parent)parent),    ui((new UiUi::Notepad)){{    ui->setupUi((this);     this->setCentralWidget(ui(ui->textEdit););    connect(ui(ui->actionNew, &QAction::triggered, this, &Notepad::newDocument););    connect(ui(ui->actionOpen, &QAction::triggered, this, &Notepad::open););    connect(ui(ui->actionSave, &QAction::triggered, this, &Notepad::save););    connect(ui(ui->actionSave_as, &QAction::triggered, this, &Notepad::saveAs););    connect(ui(ui->actionPrint, &QAction::triggered, this, &Notepad::print););    connect(ui(ui->actionExit, &QAction::triggered, this, &Notepad::exit););    connect(ui(ui->actionCopy, &QAction::triggered, this, &Notepad::copy););    connect(ui(ui->actionCut, &QAction::triggered, this, &Notepad::cut););    connect(ui(ui->actionPaste, &QAction::triggered, this, &Notepad::paste););    connect(ui(ui->actionUndo, &QAction::triggered, this, &Notepad::undo););    connect(ui(ui->actionRedo, &QAction::triggered, this, &Notepad::redo););    connect(ui(ui->actionFont, &QAction::triggered, this, &Notepad::selectFont););    connect(ui(ui->actionBold, &QAction::triggered, this, &Notepad::setFontBold););    connect(ui(ui->actionUnderline, &QAction::triggered, this, &Notepad::setFontUnderline););    connect(ui(ui->actionItalic, &QAction::triggered, this, &Notepad::setFontItalic););    connect(ui(ui->actionAbout, &QAction::triggered, this, &Notepad::about););// Disable menu actions for unavailable features#if !defined(QT_PRINTSUPPORT_LIB) || !QT_CONFIG(printer)    ui->actionPrint->setEnabled((false);#endif#if !QT_CONFIG(clipboard)    ui->actionCut->setEnabled((false);    ui->actionCopy->setEnabled((false);    ui->actionPaste->setEnabled((false);#endif}}NotepadNotepad::~Notepad()(){{    delete ui;;}}void NotepadNotepad::newDocument()(){{    currentFile.clear();();    ui->textEdit->setText((QString());}}void NotepadNotepad::open()(){{    QString fileName = QFileDialog::getOpenFileName((this, "Open the file");     QFile file(fileName);(fileName);    currentFile = fileName;    ;    if ((!file.open((QIODevice::ReadOnly  | QFile::Text)) {        )) {        QMessageBox::warning((this, "Warning", "Cannot open file: " + file.errorString());        ());        return;    }}    setWindowTitle(fileName);(fileName);    QTextStream in(in(&file);    );    QString text = inin.readAll();();    ui->textEdit->setText(text);(text);    file.close();();}}void NotepadNotepad::save()(){{    QString fileName;    ;    // If we don't have a filename from before, get one.    if (currentFile(currentFile.isEmpty()) {()) {        fileName = QFileDialog::getSaveFileName((this, "Save");        currentFile = fileName;;    } } else {{        fileName = currentFile;;    }}    QFile file(fileName);    (fileName);    if ((!file.open((QIODevice::WriteOnly  | QFile::Text)) {        )) {        QMessageBox::warning((this, "Warning", "Cannot save file: " + file.errorString());        ());        return;    }}    setWindowTitle(fileName);(fileName);    QTextStream out(out(&file);    );    QString text = ui->textEdit->toPlainText();();    out out << text;; file.close();(); }} void NotepadNotepad::saveAs()() {{ QString fileName = QFileDialog::getSaveFileName((this, "Save as"); QFile file(fileName);(fileName); if ((!file.open((QFile::WriteOnly | QFile::Text)) { )) { QMessageBox::warning((this, "Warning", "Cannot save file: " + file.errorString()); ()); return; }} currentFile = fileName;; setWindowTitle(fileName);(fileName); QTextStream out(out(&file); ); QString text = ui->textEdit->toPlainText();();    out out << text;; file.close();(); }} void NotepadNotepad::print()() {{ #if defined(QT_PRINTSUPPORT_LIB) && QT_CONFIG(printer) QPrinter printDev; ; #if QT_CONFIG(printdialog) QPrintDialog dialog((&printDev, this); if (dialog(dialog.exec() () == QDialog::Rejected) ) return; #endif // QT_CONFIG(printdialog) // QT_CONFIG(printdialog) ui->textEdit->print((&printDev););#endif // QT_CONFIG(printer) // QT_CONFIG(printer)}}void NotepadNotepad::exit()(){{    QCoreApplication::quit();();}}void NotepadNotepad::copy()(){{#if QT_CONFIG(clipboard)    ui->textEdit->copy();();#endif}}void NotepadNotepad::cut()(){{#if QT_CONFIG(clipboard)    ui->textEdit->cut();();#endif}}void NotepadNotepad::paste()(){{#if QT_CONFIG(clipboard)    ui->textEdit->paste();();#endif}}void NotepadNotepad::undo()(){{     ui->textEdit->undo();();}}void NotepadNotepad::redo()(){{    ui->textEdit->redo();();}}void NotepadNotepad::selectFont()(){{    bool fontSelected;bool fontSelected;    QFont font = QFontDialog::getFont((&fontSelected, this);     if (fontSelected)(fontSelected)        ui->textEdit->setFont(font);(font);}}

以下各行包括由向导生成的Notepad类头文件和由uic工具生成的UI头文件：

#include "notepad.h" "notepad.h"#include "ui_notepad.h" "ui_notepad.h"

以下行定义了Notepad构造函数：

Notepad::Notepad((QWidget *parent) :) :

以下行调用QMainWindow构造函数，该构造函数是Notepad类的基类：

    QMainWindow(parent)parent),

下面的行创建UI类实例并将其分配给ui成员：

 ui((new UiUi::Notepad))

以下行设置了UI：

    ui->setupUi((this);

在析构函数中，我们删除ui：

Notepad::~Notepad()(){{    delete ui;;}}

Notepad::Notepad((QWidget *parent) :    ) :    QMainWindow(parent)parent),    ui((new UiUi::Notepad)){{    ui->setupUi((this);     this->setCentralWidget(ui(ui->textEdit););    connect(ui(ui->actionNew, &QAction::triggered, this, &Notepad::newDocument););    connect(ui(ui->actionOpen, &QAction::triggered, this, &Notepad::open););    connect(ui(ui->actionSave, &QAction::triggered, this, &Notepad::save););    connect(ui(ui->actionSave_as, &QAction::triggered, this, &Notepad::saveAs););    connect(ui(ui->actionPrint, &QAction::triggered, this, &Notepad::print););    connect(ui(ui->actionExit, &QAction::triggered, this, &Notepad::exit););    connect(ui(ui->actionCopy, &QAction::triggered, this, &Notepad::copy););    connect(ui(ui->actionCut, &QAction::triggered, this, &Notepad::cut););    connect(ui(ui->actionPaste, &QAction::triggered, this, &Notepad::paste););    connect(ui(ui->actionUndo, &QAction::triggered, this, &Notepad::undo););    connect(ui(ui->actionRedo, &QAction::triggered, this, &Notepad::redo););    connect(ui(ui->actionFont, &QAction::triggered, this, &Notepad::selectFont););    connect(ui(ui->actionBold, &QAction::triggered, this, &Notepad::setFontBold););    connect(ui(ui->actionUnderline, &QAction::triggered, this, &Notepad::setFontUnderline););    connect(ui(ui->actionItalic, &QAction::triggered, this, &Notepad::setFontItalic););    connect(ui(ui->actionAbout, &QAction::triggered, this, &Notepad::about););// Disable menu actions for unavailable features#if !defined(QT_PRINTSUPPORT_LIB) || !QT_CONFIG(printer)    ui->actionPrint->setEnabled((false);#endif#if !QT_CONFIG(clipboard)    ui->actionCut->setEnabled((false);    ui->actionCopy->setEnabled((false);    ui->actionPaste->setEnabled((false);#endif}}

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