Qt中的键盘事件（QTextBrowser的网址切换）

在Qt中,可以使用 void QWidget::keyPressEvent ( QKeyEvent * k )来进行键盘响应,例如:

---

void Form1::keyPressEvent( QKeyEvent *k )
{
    if(k->key() == Key_A)
    {
      this->focusNextPrevChild(FALSE);//按A时焦点切换至上一部件
    }
    else if(k->key() == Key_D)
    {
      this->focusNextPrevChild(TRUE);//按D时焦点切换至下一部件
    }
    else if(k->key() == Key_W)
    {
      if(k->state() == Qt::ShiftButton)
      {
         this->resize(100,100);//当按下Shift+W时改变窗口大小
      }
    }
}

---

但是,有一些特殊的按键比如说Tab键,如果在keyPressEvent中实现则是不能成功的,因为默认Tab事件(切换焦点)被先捕获了,默认Tab和Shift+Tab事件定义在qwidget.h中,代码为:

---

case QEvent::KeyPress: {
        QKeyEvent *k = (QKeyEvent *)e;
        bool res = FALSE;
        if ( k->key() == Key_Backtab ||
        (k->key() == Key_Tab &&
        (k->state() & ShiftButton)) ) {
        QFocusEvent::setReason( QFocusEvent::Tab );
        res = focusNextPrevChild( FALSE );
        QFocusEvent::resetReason();

        } else if ( k->key() == Key_Tab ) {
        QFocusEvent::setReason( QFocusEvent::Tab );
        res = focusNextPrevChild( TRUE );
        QFocusEvent::resetReason();
        }
}

---

所以我们要在之前就实现我们自己的Tab事件.实现代码如下:

bool MyWidget::event(QEvent *event)

 {

     if (event->type() == QEvent::KeyPress) {

         QKeyEvent *ke = static_cast<QKeyEvent *>(event);

         if (ke->key() == Qt::Key_Tab) {

             // special tab handling here

             return true;

         }

     } else if (event->type() == MyCustomEventType) {

         MyCustomEvent *myEvent = static_cast<MyCustomEvent *>(event);

         // custom event handling here

         return true;

     }



     return QWidget::event(event);

 }

QTextBrowser中的网址切换
void ALMTextView::keyPressEvent(QKeyEvent* e)
{
   AMDEBUG("ALMTextView special key event\n");
   QScrollBar *sbv = verticalScrollBar();
    switch( e->key() ) {
        //case Key_Right:
        case Key_Down:
            if ( !selectNextPrevHref( TRUE ) )
            {
                // scroll the screen down by one page
            if (sbv->value() == sbv->maxValue())
            {
                printf("asdasdasdasdasdasda\n");
                this->focusNextPrevChild(TRUE);
            }
                sbv->setValue( sbv->value() + (sbv->pageStep() >> 1) );
                selectNextPrevHref( TRUE );
            }
            e->accept();
            return;
        //case Key_Left:
        case Key_Up:
            if ( !selectNextPrevHref( FALSE ) ){
                // scroll the screen up by one page
                if(sbv->value() == 0)
                {
                        printf("1234567890\n");
                        this->focusNextPrevChild(FALSE);
                }
                sbv->setValue( sbv->value() - (sbv->pageStep() >> 1) );
                selectNextPrevHref( FALSE );
            }
            e->accept();
            return;
    }
    QTextView::keyPressEvent(e);
}