怎样控制Qt标题栏(How can I handle events in the titlebar and change its color etc ? )

 

(原文:http://www.qtsoftware.com/developer/faqs/faq.2007-04-25.2011048382)

 

The titlebar belongs to the OS and we don’t have control over that one. You
can create your own titlebar, but note that this requires some work. In order
to create your own titlebar then make a QWidget subclass that contains three
toolbuttons that handle the close, minimize and maximize events in addition to
the moving of the window. Then make a QFrame subclass which does not have a
titlebar provided via the window system. This is done by setting the
Qt::FramelessWindowHint window flag, however this will make it impossible to
resize or move the window via the window system. What can be done is you can
add your custom titlbar as a private member to the frame and add the it first
to the frame’s vertical layout. The frame also needs a content widget which
allows widgets to be added to it. Finally the QFrame subclass needs to
reimplement the mouse events to handle the resizing and moving of the window.

The example below demonstrates how this can be achieved.

 

#include <QtGui> 
  
class TitleBar : public QWidget
{ 
    Q_OBJECT 
public: 
    TitleBar(QWidget *parent) 
    { 
        // Don't let this widget inherit the parent's backround color 
        setAutoFillBackground(true); 
        // Use a brush with a Highlight color role to render the background  
        setBackgroundRole(QPalette::Highlight); 
          
        minimize = new QToolButton(this); 
        maximize = new QToolButton(this); 
        close= new QToolButton(this); 
          
        // Use the style to set the button pixmaps 
        QPixmap pix = style()->standardPixmap(QStyle::SP_TitleBarCloseButton); 
        close->setIcon(pix); 
          
        maxPix = style()->standardPixmap(QStyle::SP_TitleBarMaxButton); 
        maximize->setIcon(maxPix); 
          
        pix = style()->standardPixmap(QStyle::SP_TitleBarMinButton); 
        minimize->setIcon(pix); 
  
        restorePix = style()->standardPixmap(QStyle::SP_TitleBarNormalButton); 
          
        minimize->setMinimumHeight(20); 
        close->setMinimumHeight(20); 
        maximize->setMinimumHeight(20); 
          
          
        QLabel *label = new QLabel(this); 
        label->setText("Window Title"); 
        parent->setWindowTitle("Window Title"); 
          
        QHBoxLayout *hbox = new QHBoxLayout(this); 
          
        hbox->addWidget(label); 
        hbox->addWidget(minimize); 
        hbox->addWidget(maximize); 
        hbox->addWidget(close); 
          
        hbox->insertStretch(1, 500); 
        hbox->setSpacing(0); 
        setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Fixed); 
          
        maxNormal = false; 
          
        connect(close, SIGNAL( clicked() ), parent, SLOT(close() ) ); 
        connect(minimize, SIGNAL( clicked() ), this, SLOT(showSmall() ) ); 
        connect(maximize, SIGNAL( clicked() ), this, SLOT(showMaxRestore() ) ); 
    } 
      
public slots: 
    void showSmall() 
    { 
        parentWidget()->showMinimized(); 
    } 
      
    void showMaxRestore() 
    { 
        if (maxNormal) { 
            parentWidget()->showNormal(); 
            maxNormal = !maxNormal; 
            maximize->setIcon(maxPix); 
        } else { 
            parentWidget()->showMaximized(); 
            maxNormal = !maxNormal; 
            maximize->setIcon(restorePix); 
        } 
    } 
protected: 
    void mousePressEvent(QMouseEvent *me) 
    { 
        startPos = me->globalPos(); 
        clickPos = mapToParent(me->pos()); 
    } 
    void mouseMoveEvent(QMouseEvent *me) 
    { 
        if (maxNormal) 
            return; 
        parentWidget()->move(me->globalPos() - clickPos); 
    } 
  
private: 
    QToolButton *minimize; 
    QToolButton *maximize; 
    QToolButton *close; 
    QPixmap restorePix, maxPix; 
    bool maxNormal; 
    QPoint startPos; 
    QPoint clickPos; 
}; 
  
class Frame : public QFrame
{ 
public: 
      
    Frame() 
    { 
        m_mouse_down = false; 
        setFrameShape(Panel); 
          
        // Make this a borderless window which can't 
        // be resized or moved via the window system 
        setWindowFlags(Qt::FramelessWindowHint); 
        setMouseTracking(true); 
          
        m_titleBar = new TitleBar(this); 
          
        m_content = new QWidget(this); 
          
        QVBoxLayout *vbox = new QVBoxLayout(this); 
        vbox->addWidget(m_titleBar); 
        vbox->setMargin(0); 
        vbox->setSpacing(0); 
          
        QVBoxLayout *layout = new QVBoxLayout(this); 
        layout->addWidget(m_content); 
        layout->setMargin(5); 
        layout->setSpacing(0); 
        vbox->addLayout(layout); 
    } 
      
    // Allows you to access the content area of the frame 
    // where widgets and layouts can be added 
    QWidget *contentWidget() const { return m_content; } 
      
    TitleBar *titleBar() const { return m_titleBar; } 
      
    void mousePressEvent(QMouseEvent *e) 
    { 
        m_old_pos = e->pos(); 
        m_mouse_down = e->button() == Qt::LeftButton; 
    } 
      
    void mouseMoveEvent(QMouseEvent *e) 
    { 
        int x = e->x(); 
        int y = e->y(); 
          
        if (m_mouse_down) { 
            int dx = x - m_old_pos.x(); 
            int dy = y - m_old_pos.y(); 
              
            QRect g = geometry(); 
              
            if (left) 
                g.setLeft(g.left() + dx); 
            if (right) 
                g.setRight(g.right() + dx); 
            if (bottom) 
                g.setBottom(g.bottom() + dy); 
              
            setGeometry(g); 
              
            m_old_pos = QPoint(!left ? e->x() : m_old_pos.x(), e->y()); 
        } else { 
            QRect r = rect(); 
            left = qAbs(x - r.left()) <= 5; 
            right = qAbs(x - r.right()) <= 5; 
            bottom = qAbs(y - r.bottom()) <= 5; 
            bool hor = left | right; 
              
            if (hor && bottom) { 
                if (left) 
                    setCursor(Qt::SizeBDiagCursor); 
                else 
                    setCursor(Qt::SizeFDiagCursor); 
            } else if (hor) { 
                setCursor(Qt::SizeHorCursor); 
            } else if (bottom) { 
                setCursor(Qt::SizeVerCursor); 
            } else { 
                setCursor(Qt::ArrowCursor); 
            } 
        } 
    } 
      
    void mouseReleaseEvent(QMouseEvent *e) 
    { 
        m_mouse_down = false; 
    } 
      
private: 
    TitleBar *m_titleBar; 
    QWidget *m_content; 
    QPoint m_old_pos; 
    bool m_mouse_down; 
    bool left, right, bottom; 
}; 
  
  
#include "main.moc" 
  
int main(int argc, char **argv) 
{ 
    QApplication app(argc, argv); 
      
    Frame box; 
    box.move(0,0); 
      
    QVBoxLayout *l = new QVBoxLayout(box.contentWidget()); 
    l->setMargin(0); 
    QTextEdit *edit = new QTextEdit(box.contentWidget()); 
    l->addWidget(edit); 
      
    box.show(); 
    return app.exec();     
}

 

 

 

Note that some strange behavior may be seen when resizing the window really
small horizonally to the right on Windows (the window will start moving
instead of resizing). This is due to limitations on Windows and there is
nothing we can do about this unfortunately.