创建一个主窗口，具有菜单、工具栏、状态栏和对话框之类的界面和功能。实现电子制表软件的主窗口框架。

效果：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QAction>
#include <QLabel>
#include <QFileDialog>
#include <QMessageBox>
#include <QStatusBar>
#include <QToolBar>
#include <QMenu>
#include <QMenuBar>
#include "spreadsheet.h"
#include "finddialog.h"

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow();

protected:
	//是Qwidget类中的一个虚函数，当用户关闭这个窗口时会被自动调用诶，可以在里面做自己想做的事情。
    void closeEvent(QCloseEvent *event);

private slots:
	//声明了很多槽函数，作为窗口的功能菜单项和其中子菜单项 File->New这种的。    
	//File
	void newFile();
    void open();
    bool save();
    bool saveAs();
    void openRecentFile();
	//close()

	//Edit
    void find();
    void goToCell();

	//Tools
    void sort();

	//Help
    void about();

	//
    void updateStatusBar();
    void spreadsheetModified();

private:
    //私有函数实现菜单功能
    void createActions();
    void createMenus();
    void createContextMenu();
    void createToolBars();
    void createStatusBar();
    void readSettings();
    void writeSettings();
    bool okToContinue();
    bool loadFile(const QString &fileName);
    bool saveFile(const QString &fileName);
    void setCurrentFile(const QString &fileName);
    void updateRecentFileActions();
    QString strippedName(const QString &fullFileName);

    Spreadsheet *spreadsheet;
    FindDialog *findDialog;
    QLabel *locationLabel;
    QLabel *formulaLabel;
    QStringList recentFiles;
    QString curFile;

    enum { MaxRecentFiles = 5 };
    QAction *recentFileActions[MaxRecentFiles];
    QAction *separatorAction;

    QMenu *fileMenu;
    QMenu *editMenu;
    QMenu *selectSubMenu;
    QMenu *toolsMenu;
    QMenu *optionsMenu;
    QMenu *helpMenu;
    QToolBar *fileToolBar;
    QToolBar *editToolBar;
    QAction *newAction;
    QAction *openAction;
    QAction *saveAction;
    QAction *saveAsAction;
    QAction *exitAction;
    QAction *cutAction;
    QAction *copyAction;
    QAction *pasteAction;
    QAction *deleteAction;
    QAction *selectRowAction;
    QAction *selectColumnAction;
    QAction *selectAllAction;
    QAction *findAction;
    QAction *goToCellAction;
    QAction *recalculateAction;
    QAction *sortAction;
    QAction *showGridAction;
    QAction *autoRecalcAction;
    QAction *aboutAction;
    QAction *aboutQtAction;
};
#endif

mainwindow.cpp

1）先来看构造函数

MainWindow::MainWindow()
{
	//先创建一个Spreadsheet表格窗口部件并且设置为中央窗口
    spreadsheet = new Spreadsheet;
    setCentralWidget(spreadsheet);

	//相当于初始化窗口,createXXXX创建窗口中的其他部分
    createActions();
    createMenus();
    createContextMenu();
    createToolBars();
    createStatusBar();
    
    readSettings();

    findDialog = 0;
    setWindowIcon(QIcon("images/icon.png"));
    setCurrentFile("");
}

把findDialog初始化为空，在第一次调用find（）时再创建该对象；

这里没有采用Qt的资源机制来加载图片；

2）创建菜单和工具栏

void MainWindow::createActions()
{
	//创建File->New
    newAction = new QAction(tr("&New"), this);
    newAction->setIcon(QIcon("images/new.png"));
    newAction->setShortcut(QKeySequence::New);
    newAction->setStatusTip(tr("Create a new spreadsheet file"));
    connect(newAction, SIGNAL(triggered()), this, SLOT(newFile()));
	//创建File->Open
	openAction = new QAction(tr("&Open..."), this);
    openAction->setIcon(QIcon("images/open.png"));
    openAction->setShortcut(QKeySequence::Open);
    openAction->setStatusTip(tr("Open an existing spreadsheet file"));
    connect(openAction, SIGNAL(triggered()), this, SLOT(open()));
	//创建File->Save
	saveAction = new QAction(tr("&Save"), this);
    saveAction->setIcon(QIcon("images/save.png"));
    saveAction->setShortcut(QKeySequence::Save);
    saveAction->setStatusTip(tr("Save the spreadsheet to disk"));
    connect(saveAction, SIGNAL(triggered()), this, SLOT(save()));
	//创建File->SaveAs
    saveAsAction = new QAction(tr("Save &As..."), this);
    saveAsAction->setStatusTip(tr("Save the spreadsheet under a new name"));
    connect(saveAsAction, SIGNAL(triggered()), this, SLOT(saveAs()));
	//创建File->recentFileActions 最近打开文件，检测最近最多的五个
    for (int i = 0; i < MaxRecentFiles; ++i) 
	{
        recentFileActions[i] = new QAction(this);
        recentFileActions[i]->setVisible(false);//创建了但是不显示
        connect(recentFileActions[i], SIGNAL(triggered()), this, SLOT(openRecentFile()));
    }
	//创建File->Exit
	exitAction = new QAction(tr("E&xit"), this);
    exitAction->setShortcut(tr("Ctrl+Q"));
    exitAction->setStatusTip(tr("Exit the application"));
    connect(exitAction, SIGNAL(triggered()), this, SLOT(close()));
	//创建Edit->Cut
    cutAction = new QAction(tr("Cu&t"), this);
    cutAction->setIcon(QIcon("images/cut.png"));
    cutAction->setShortcut(QKeySequence::Cut);
    cutAction->setStatusTip(tr("Cut the current selection's contents to the clipboard"));
    connect(cutAction, SIGNAL(triggered()), spreadsheet, SLOT(cut()));
	//创建Edit->Copy
	copyAction = new QAction(tr("&Copy"), this);
    copyAction->setIcon(QIcon("images/copy.png"));
    copyAction->setShortcut(QKeySequence::Copy);
    copyAction->setStatusTip(tr("Copy the current selection's contents to the clipboard"));
    connect(copyAction, SIGNAL(triggered()), spreadsheet, SLOT(copy()));
	//创建Edit->Paste
	pasteAction = new QAction(tr("&Paste"), this);
    pasteAction->setIcon(QIcon("images/paste.png"));
    pasteAction->setShortcut(QKeySequence::Paste);
    pasteAction->setStatusTip(tr("Paste the clipboard's contents into the current selection"));
    connect(pasteAction, SIGNAL(triggered()), spreadsheet, SLOT(paste()));
	//创建Edit->Delete
    deleteAction = new QAction(tr("&Delete"), this);
    deleteAction->setShortcut(QKeySequence::Delete);
    deleteAction->setStatusTip(tr("Delete the current selection's contents"));
    connect(deleteAction, SIGNAL(triggered()), spreadsheet, SLOT(del()));
	//创建Edit->Select->Row
    selectRowAction = new QAction(tr("&Row"), this);
    selectRowAction->setStatusTip(tr("Select all the cells in the current row"));
    connect(selectRowAction, SIGNAL(triggered()), spreadsheet, SLOT(selectCurrentRow()));
	//创建Edit->Select->Column
    selectColumnAction = new QAction(tr("&Column"), this);
    selectColumnAction->setStatusTip(tr("Select all the cells in the current column"));
    connect(selectColumnAction, SIGNAL(triggered()), spreadsheet, SLOT(selectCurrentColumn()));
	//创建Edit->Select->All
    selectAllAction = new QAction(tr("&All"), this);
    selectAllAction->setShortcut(QKeySequence::SelectAll);
    selectAllAction->setStatusTip(tr("Select all the cells in the spreadsheet"));
    connect(selectAllAction, SIGNAL(triggered()), spreadsheet, SLOT(selectAll()));
	//创建Edit->Find
	findAction = new QAction(tr("&Find..."), this);
    findAction->setIcon(QIcon("images/find.png"));
    findAction->setShortcut(QKeySequence::Find);
    findAction->setStatusTip(tr("Find a matching cell"));
    connect(findAction, SIGNAL(triggered()), this, SLOT(find()));
	//创建Edit->Go To Cell
    goToCellAction = new QAction(tr("&Go to Cell..."), this);
    goToCellAction->setIcon(QIcon("images/gotocell.png"));
    goToCellAction->setShortcut(tr("Ctrl+G"));
    goToCellAction->setStatusTip(tr("Go to the specified cell"));
    connect(goToCellAction, SIGNAL(triggered()), this, SLOT(goToCell()));
	//创建Tools->Recalculate
    recalculateAction = new QAction(tr("&Recalculate"), this);
    recalculateAction->setShortcut(tr("F9"));
    recalculateAction->setStatusTip(tr("Recalculate all the spreadsheet's formulas"));
    connect(recalculateAction, SIGNAL(triggered()), spreadsheet, SLOT(recalculate()));
	//创建Tools->Sort
    sortAction = new QAction(tr("&Sort..."), this);
    sortAction->setStatusTip(tr("Sort the selected cells or all the cells"));
    connect(sortAction, SIGNAL(triggered()), this, SLOT(sort()));
	//创建Options->Show Grid
    showGridAction = new QAction(tr("&Show Grid"), this);
    showGridAction->setCheckable(true);
    showGridAction->setChecked(spreadsheet->showGrid());
    showGridAction->setStatusTip(tr("Show or hide the spreadsheet's grid"));
    connect(showGridAction, SIGNAL(toggled(bool)), spreadsheet, SLOT(setShowGrid(bool)));

#if QT_VERSION < 0x040102
    // workaround for a QTableWidget bug in Qt 4.1.1
    connect(showGridAction, SIGNAL(toggled(bool)),
            spreadsheet->viewport(), SLOT(update()));
#endif

	//创建Options->Auto-Recalculate
	autoRecalcAction = new QAction(tr("&Auto-Recalculate"), this);
    autoRecalcAction->setCheckable(true);
    autoRecalcAction->setChecked(spreadsheet->autoRecalculate());
    autoRecalcAction->setStatusTip(tr("Switch auto-recalculation on or off"));
    connect(autoRecalcAction, SIGNAL(toggled(bool)), spreadsheet, SLOT(setAutoRecalculate(bool)));
	//创建Help->About
	aboutAction = new QAction(tr("&About"), this);
    aboutAction->setStatusTip(tr("Show the application's About box"));
    connect(aboutAction, SIGNAL(triggered()), this, SLOT(about()));
	//创建Help->About Qt
	aboutQtAction = new QAction(tr("About &Qt"), this);
    aboutQtAction->setStatusTip(tr("Show the Qt library's About box"));
    connect(aboutQtAction, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
}

就是为了创建菜单

*创建并设置动作； 

    newAction = new QAction(tr("&New"), this);
    newAction->setIcon(QIcon(":/images/new.png"));
    newAction->setShortcut(QKeySequence::New);
    newAction->setStatusTip(tr("Create a new spreadsheet file"));
    connect(newAction, SIGNAL(triggered()), this, SLOT(newFile()));

*创建菜单并添加动作到菜单；

    editMenu = menuBar()->addMenu(tr("&Edit"));
    editMenu->addAction(cutAction);
    editMenu->addAction(copyAction);
    editMenu->addAction(pasteAction);
    editMenu->addAction(deleteAction);

*创建工具栏并添加动作到工具栏。

    fileToolBar = addToolBar(tr("&File"));
    fileToolBar->addAction(newAction);
    fileToolBar->addAction(openAction);
    fileToolBar->addAction(saveAction);

3）创建一级菜单

void MainWindow::createMenus()
{
	//创建一级菜单
    fileMenu = menuBar()->addMenu(tr("&File"));
    fileMenu->addAction(newAction);
    fileMenu->addAction(openAction);
    fileMenu->addAction(saveAction);
    fileMenu->addAction(saveAsAction);
    separatorAction = fileMenu->addSeparator();
    for (int i = 0; i < MaxRecentFiles; ++i)
        fileMenu->addAction(recentFileActions[i]);
    fileMenu->addSeparator();
    fileMenu->addAction(exitAction);

    editMenu = menuBar()->addMenu(tr("&Edit"));
    editMenu->addAction(cutAction);
    editMenu->addAction(copyAction);
    editMenu->addAction(pasteAction);
    editMenu->addAction(deleteAction);

    selectSubMenu = editMenu->addMenu(tr("&Select"));
    selectSubMenu->addAction(selectRowAction);
    selectSubMenu->addAction(selectColumnAction);
    selectSubMenu->addAction(selectAllAction);

    editMenu->addSeparator();
    editMenu->addAction(findAction);
    editMenu->addAction(goToCellAction);

    toolsMenu = menuBar()->addMenu(tr("&Tools"));
    toolsMenu->addAction(recalculateAction);
    toolsMenu->addAction(sortAction);

    optionsMenu = menuBar()->addMenu(tr("&Options"));
    optionsMenu->addAction(showGridAction);
    optionsMenu->addAction(autoRecalcAction);

    menuBar()->addSeparator();

    helpMenu = menuBar()->addMenu(tr("&Help"));
    helpMenu->addAction(aboutAction);
    helpMenu->addAction(aboutQtAction);
}

4）

void MainWindow::createToolBars()
{
	//创建工具按钮
    fileToolBar = addToolBar(tr("&File"));
    fileToolBar->addAction(newAction);
    fileToolBar->addAction(openAction);
    fileToolBar->addAction(saveAction);

    editToolBar = addToolBar(tr("&Edit"));
    editToolBar->addAction(cutAction);
    editToolBar->addAction(copyAction);
    editToolBar->addAction(pasteAction);
    editToolBar->addSeparator();
    editToolBar->addAction(findAction);
    editToolBar->addAction(goToCellAction);
}

5）

void MainWindow::createStatusBar()
{
	//设置状态栏
	locationLabel = new QLabel(" W999 ");
	locationLabel->setAlignment(Qt::AlignHCenter);
	locationLabel->setMinimumSize(locationLabel->sizeHint());

	formulaLabel = new QLabel;
	formulaLabel->setIndent(3);

	statusBar()->addWidget(locationLabel);
	statusBar()->addWidget(formulaLabel, 1);

	connect(spreadsheet, SIGNAL(currentCellChanged(int, int, int, int)), this, SLOT(updateStatusBar()));
	connect(spreadsheet, SIGNAL(modified()), this, SLOT(spreadsheetModified()));

	updateStatusBar();
}

void MainWindow::updateStatusBar()
{
	//更新单元格指示器，因为SpreadSheet不会一开始就发射改变的消息所以需要spreadsheetModified()
    locationLabel->setText(spreadsheet->currentLocation());
    formulaLabel->setText(spreadsheet->currentFormula());
}

void MainWindow::spreadsheetModified()
{
    setWindowModified(true);
    updateStatusBar();
}

6）菜单功能的实现

void MainWindow::newFile()
{
    if (okToContinue()) 
	{
        spreadsheet->clear();
        setCurrentFile("");
    }
}

void MainWindow::open()
{
    if (okToContinue())
	{
        QString fileName = QFileDialog::getOpenFileName(this, tr("Open Spreadsheet"), ".", tr("Spreadsheet files (*.sp)"));
        if (!fileName.isEmpty())
            loadFile(fileName);
    }
}

bool MainWindow::save()
{
    if (curFile.isEmpty()) 
	{
        return saveAs();
    } 
	else 
	{
        return saveFile(curFile);
    }
}

bool MainWindow::saveAs()
{
    QString fileName = QFileDialog::getSaveFileName(this,  tr("Save Spreadsheet"), ".", tr("Spreadsheet files (*.sp)"));
    if (fileName.isEmpty())
        return false;
    return saveFile(fileName);
}

void MainWindow::find()
{
    if (!findDialog) 
	{
        findDialog = new FindDialog(this);
        connect(findDialog, SIGNAL(findNext(const QString &,
                                            Qt::CaseSensitivity)),
                spreadsheet, SLOT(findNext(const QString &,
                                           Qt::CaseSensitivity)));
        connect(findDialog, SIGNAL(findPrevious(const QString &,
                                                Qt::CaseSensitivity)),
                spreadsheet, SLOT(findPrevious(const QString &,
                                               Qt::CaseSensitivity)));
    }

    findDialog->show();
    findDialog->raise();
    findDialog->activateWindow();
}

void MainWindow::goToCell()
{
    GoToCellDialog dialog(this);
    if (dialog.exec()) {
        QString str = dialog.lineEdit->text().toUpper();
        spreadsheet->setCurrentCell(str.mid(1).toInt() - 1,
                                    str[0].unicode() - 'A');
    }
}

void MainWindow::sort()
{
    SortDialog dialog(this);
    QTableWidgetSelectionRange range = spreadsheet->selectedRange();
    dialog.setColumnRange('A' + range.leftColumn(),
                          'A' + range.rightColumn());

    if (dialog.exec()) 
	{
        SpreadsheetCompare compare;
        compare.keys[0] =
              dialog.primaryColumnCombo->currentIndex();
        compare.keys[1] =
              dialog.secondaryColumnCombo->currentIndex() - 1;
        compare.keys[2] =
              dialog.tertiaryColumnCombo->currentIndex() - 1;
        compare.ascending[0] =
              (dialog.primaryOrderCombo->currentIndex() == 0);
        compare.ascending[1] =
              (dialog.secondaryOrderCombo->currentIndex() == 0);
        compare.ascending[2] =
              (dialog.tertiaryOrderCombo->currentIndex() == 0);
        spreadsheet->sort(compare);
    }
}

void MainWindow::about()
{
    QMessageBox::about(this, tr("About Spreadsheet"),
            tr("<h2>Spreadsheet 1.1</h2>"
               "<p>Copyright &copy; 2008 Software Inc."
               "<p>Spreadsheet is a small application that "
               "demonstrates QAction, QMainWindow, QMenuBar, "
               "QStatusBar, QTableWidget, QToolBar, and many other "
               "Qt classes."));
}

void MainWindow::openRecentFile()
{
    if (okToContinue()) 
	{
        QAction *action = qobject_cast<QAction *>(sender());
        if (action)
            loadFile(action->data().toString());	//打开选中的最近的文件
    }
}

7）

void MainWindow::createContextMenu()
{
    spreadsheet->addAction(cutAction);
    spreadsheet->addAction(copyAction);
    spreadsheet->addAction(pasteAction);
    spreadsheet->setContextMenuPolicy(Qt::ActionsContextMenu);
}

void MainWindow::readSettings()
{
    QSettings settings("Software Inc.", "Spreadsheet");

    restoreGeometry(settings.value("geometry").toByteArray());

    recentFiles = settings.value("recentFiles").toStringList();
    updateRecentFileActions();

    bool showGrid = settings.value("showGrid", true).toBool();
    showGridAction->setChecked(showGrid);

    bool autoRecalc = settings.value("autoRecalc", true).toBool();
    autoRecalcAction->setChecked(autoRecalc);
}

void MainWindow::writeSettings()
{
    QSettings settings("Software Inc.", "Spreadsheet");

    settings.setValue("geometry", saveGeometry());
    settings.setValue("recentFiles", recentFiles);
    settings.setValue("showGrid", showGridAction->isChecked());
    settings.setValue("autoRecalc", autoRecalcAction->isChecked());
}

bool MainWindow::okToContinue()
{
	//是否修改过、是否允许保存等判定
    if (isWindowModified()) 
	{
        int r = QMessageBox::warning(this, tr("Spreadsheet"),
                        tr("The document has been modified.\n"
                           "Do you want to save your changes?"),
                        QMessageBox::Yes | QMessageBox::No
                        | QMessageBox::Cancel);
        if (r == QMessageBox::Yes) 
		{
            return save();
        } else if (r == QMessageBox::Cancel) {
            return false;
        }
    }
    return true;
}

bool MainWindow::loadFile(const QString &fileName)
{
    if (!spreadsheet->readFile(fileName)) {
        statusBar()->showMessage(tr("Loading canceled"), 2000);
        return false;
    }

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File loaded"), 2000);
    return true;
}

bool MainWindow::saveFile(const QString &fileName)
{
    if (!spreadsheet->writeFile(fileName)) {
        statusBar()->showMessage(tr("Saving canceled"), 2000);
        return false;
    }

    setCurrentFile(fileName);
    statusBar()->showMessage(tr("File saved"), 2000);
    return true;
}

void MainWindow::setCurrentFile(const QString &fileName)
{
    curFile = fileName;
    setWindowModified(false);

    QString shownName = tr("Untitled");
    if (!curFile.isEmpty()) {
        shownName = strippedName(curFile);
        recentFiles.removeAll(curFile);
        recentFiles.prepend(curFile);
        updateRecentFileActions();
    }

    setWindowTitle(tr("%1[*] - %2").arg(shownName).arg(tr("Spreadsheet")));
}

void MainWindow::updateRecentFileActions()
{
    QMutableStringListIterator i(recentFiles);
    while (i.hasNext()) 
	{
        if (!QFile::exists(i.next()))
            i.remove();
    }

    for (int j = 0; j < MaxRecentFiles; ++j) {
        if (j < recentFiles.count()) {
            QString text = tr("&%1 %2")
                           .arg(j + 1)
                           .arg(strippedName(recentFiles[j]));
            recentFileActions[j]->setText(text);
            recentFileActions[j]->setData(recentFiles[j]);
            recentFileActions[j]->setVisible(true);
        } else {
            recentFileActions[j]->setVisible(false);
        }
    }
    separatorAction->setVisible(!recentFiles.isEmpty());
}

QString MainWindow::strippedName(const QString &fullFileName)
{
    return QFileInfo(fullFileName).fileName();
}

void MainWindow::closeEvent(QCloseEvent *event)
{
    if (okToContinue()) 
	{
        writeSettings();
        event->accept();
    } 
	else 
	{
        event->ignore();
    }
}

就好像PS打开时会有一个图片显示几秒加载一些东西的时候

main.cpp

#include <QApplication>
#include <QSplashScreen>
#include <QDateTime>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
	QSplashScreen *splash = new QSplashScreen;
	splash->setPixmap(QPixmap("images/qtStart.png"));
	splash->show();

	/*使程序在显示启动画面的同时仍能响应鼠标等其他事件*/
	app.processEvents();

	Qt::Alignment topRight = Qt::AlignRight | Qt::AlignLeft;
	splash->showMessage(QObject::tr("正在启动程序..."), topRight, Qt::white);
	
    MainWindow mainWin;

	splash->showMessage(QObject::tr("发现二次元，正在扫描..."), topRight, Qt::white);

	//loadModules();

	splash->showMessage(QObject::tr("最后一步..."), topRight, Qt::white);
	
	//establishConnections();

	QDateTime n = QDateTime::currentDateTime();
	QDateTime now;
	do {
		now = QDateTime::currentDateTime();
		app.processEvents();
	} while (n.secsTo(now) <= 2);//5为需要延时的秒数

	mainWin.show();

	splash->finish(&mainWin);
	delete splash;

    return app.exec();
}

本文还未完，在实现表格后台功能后才行，在下一章继续..