1. 程式人生 > >常見的幾個Qt程式設計問題的處理

常見的幾個Qt程式設計問題的處理

1、如果在窗體關閉前自行判斷是否可關閉
答:重新實現這個窗體的closeEvent()函式,加入判斷操作
QUOTE:
void MainWindow::closeEvent(QCloseEvent *event)
{
    if (maybeSave())
    {
        writeSettings();
         event->accept();

    }
    else
    {
         event->ignore();
    }
}


2、如何用開啟和儲存檔案對話
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、如果建立Actions(可在選單和工具欄裡使用這些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("E&xit"), 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("Cu&t"), 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、如果建立主選單
答:採用上面的QAction的幫助,建立主選單
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、如果建立工具欄
答:採用上面的QAction的幫助,建立工具欄
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、如何使用配置檔案儲存配置
答:使用QSettings類
QUOTE:
    QSettings settings("Trolltech", "Application Example");
    QPoint pos = settings.value("pos", QPoint(200, 200)).toPoint();
    QSize size = settings.value("size", QSize(400, 400)).toSize();


QUOTE:
    QSettings settings("Trolltech", "Application Example");
    settings.setValue("pos", pos());
    settings.setValue("size", size());


7、如何使用警告、資訊等對話方塊
答:使用QMessageBox類的靜態方法
QUOTE:
int ret = QMessageBox::warning(this, tr("Application"),
                tr("The document has been modified.\n"
                  "Do you want to save your changes?"),
                QMessageBox::Yes | QMessageBox::Default,
                QMessageBox::No,
                QMessageBox::Cancel | QMessageBox::Escape);
        if (ret == QMessageBox::Yes)
          return save();
        else if (ret == QMessageBox::Cancel)
          return false;


8、如何使通用對話方塊中文化
答:對話方塊的中文化
比如說,QColorDialog的與文字相關的部分,主要在qcolordialog.cpp檔案中,我們可以從qcolordialog.cpp用 lupdate生成一個ts檔案,然後用自定義這個ts檔案的翻譯,再用lrelease生成一個.qm檔案,當然了,主程式就要改變要支援多國語言了,使用這個.qm檔案就可以了。

另外,還有一個更快的方法,在原始碼解開後有一個目錄translations,下面有一些.ts, .qm檔案,我們拷貝一個:
QUOTE:
cp src/translations/qt_untranslated.ts ./qt_zh_CN.ts

然後,我們就用Linguist開啟這個qt_zh_CN.ts,進行翻譯了,翻譯完成後,儲存後,再用lrelease命令生成qt_zh_CN.qm,這樣,我們把它加入到我們的qt project中,那些系統的對話方塊,選單等等其它的預設是英文的東西就能顯示成中文了。

9、在Windows下Qt裡為什麼沒有終端輸出?
答:把下面的配置項加入到.pro檔案中
QUOTE:
win32:CONFIG += console


10、Qt 4 for X11 OpenSource版如何靜態連結?
答:編譯安裝的時候加上-static選項
QUOTE: ./configure -static   //一定要加static選項
gmake
gmake install

然後,在Makefile檔案中加 static 選項,就可以連線靜態庫了。