QT 技术应用常用问题解答

1、如果在窗体关闭前自行判断是否可关闭

答：重新实现这个窗体的closeEvent()函数，加入判断操作

Quote:

void MainWindow::closeEvent(QCloseEvent *event)

{

if (maybeSave())

{

writeSettings();

event->accept();

}

else

{

event->ignore();

}

}

2、如何用打开和保存文件对话

答：使用QFileDialog

Quote:

QString fileName = QFileDialog::getOpenFileName(this);

if (!fileName.isEmpty())

{

loadFile(fileName);

}

Quote:

QString fileName = QFileDialog::getSaveFileName(this);

if (fileName.isEmpty())

{

return false;

}

3、如果创建Actions(可在菜单和工具栏里使用这些Action)

答：

Quote:

newAct = new QAction(QIcon(:/images/new.png), tr(New), this);

newAct->setShortcut(tr(Ctrl+N));

newAct->setStatusTip(tr(Create a new file));

connect(newAct, SIGNAL(triggered()), this, SLOT(newFile()));

openAct = new QAction(QIcon(:/images/open.png), tr(Open...), this);

openAct->setShortcut(tr(Ctrl+O));

openAct->setStatusTip(tr(Open an existing file));

connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

saveAct = new QAction(QIcon(:/images/save.png), tr(Save), this);

saveAct->setShortcut(tr(Ctrl+S));

saveAct->setStatusTip(tr(Save the document to disk));

connect(saveAct, SIGNAL(triggered()), this, SLOT(save()));

saveAsAct = new QAction(tr(Save As...), this);

saveAsAct->setStatusTip(tr(Save the document under a new name));

connect(saveAsAct, SIGNAL(triggered()), this, SLOT(saveAs()));

exitAct = new QAction(tr(Exit), this);

exitAct->setShortcut(tr(Ctrl+Q));

exitAct->setStatusTip(tr(Exit the application));

connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));

cutAct = new QAction(QIcon(:/images/cut.png), tr(Cut), this);

cutAct->setShortcut(tr(Ctrl+X));

cutAct->setStatusTip(tr(Cut the current selection's contents to the

clipboard));

connect(cutAct, SIGNAL(triggered()), textEdit, SLOT(cut()));

copyAct = new QAction(QIcon(:/images/copy.png), tr(Copy), this);

copyAct->setShortcut(tr(Ctrl+C));

copyAct->setStatusTip(tr(Copy the current selection's contents to the

clipboard));

connect(copyAct, SIGNAL(triggered()), textEdit, SLOT(copy()));

pasteAct = new QAction(QIcon(:/images/paste.png), tr(Paste), this);

pasteAct->setShortcut(tr(Ctrl+V));

pasteAct->setStatusTip(tr(Paste the clipboard's contents into the current

selection));

connect(pasteAct, SIGNAL(triggered()), textEdit, SLOT(paste()));

aboutAct = new QAction(tr(About), this);

aboutAct->setStatusTip(tr(Show the application's About box));

connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));

aboutQtAct = new QAction(tr(About Qt), this);

aboutQtAct->setStatusTip(tr(Show the Qt library's About box));

connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));

4、如果创建主菜单

答：采用上面的QAction的帮助，创建主菜单

Quote:

fileMenu = menuBar()->addMenu(tr(File));

fileMenu->addAction(newAct);

fileMenu->addAction(openAct);

fileMenu->addAction(saveAct);

fileMenu->addAction(saveAsAct);

fileMenu->addSeparator();

fileMenu->addAction(exitAct);

editMenu = menuBar()->addMenu(tr(Edit));

editMenu->addAction(cutAct);

editMenu->addAction(copyAct);

editMenu->addAction(pasteAct);

menuBar()->addSeparator();

helpMenu = menuBar()->addMenu(tr(Help));

helpMenu->addAction(aboutAct);

helpMenu->addAction(aboutQtAct);

5、如果创建工具栏

答：采用上面的QAction的帮助，创建工具栏

Quote:

fileToolBar = addToolBar(tr(File));

fileToolBar->addAction(newAct);

fileToolBar->addAction(openAct);

fileToolBar->addAction(saveAct);

editToolBar = addToolBar(tr(Edit));

editToolBar->addAction(cutAct);

editToolBar->addAction(copyAct);

editToolBar->addAction(pasteAct);

6、如何使用配置文件保存配置

答：使用QSettings类

Quote:

QSettings setting