qt按键焦点切换

实现内容

对于4个控件，当按下左右按键时焦点可以左右切换，如下图：

关键代码

1.实现焦点切换功能

使用事件过滤器来对事件进行分类处理这样就可以在a1至a4等控件上实现，按下右键后即把焦点转到右边控件上的功能。

先在aa.h中加入

public slots:

booleventFilter(QObject *,QEvent *);

在aa.cpp中定义函数

bool aa::eventFilter(QObject *watched, QEvent*event)

{

if(watched == ui->a1 || watched == ui->a2 || watched == ui->a3|| watched == ui->a4)//确认可控的控件

{

if(event->type() == QEvent::KeyPress)//如果检测到按键

{

bool f1 =ui->a1->hasFocus();

bool f2 =ui->a2->hasFocus();

bool f3 =ui->a3->hasFocus();

bool f4 =ui->a4->hasFocus();定义4个获得焦点的状态

QKeyEvent *key_event = static_cast<QKeyEvent *>(event); //将事件转化为键盘事件

if(key_event->key() == Qt::Key_Right)//右键

{

if(f1)//焦点在a1处

{

focusNextChild();//焦点移动

ui->a2->setFocus();//移动到a2

}

if(f2)

{

focusNextChild();

ui->a3->setFocus();

}

if(f3)

{

focusNextChild();

ui->a4->setFocus();

}

}

if(key_event->key() == Qt::Key_Left)

{

if(f4)

{

focusNextChild();

ui->a3->setFocus();

}

if(f3)

{

focusNextChild();

ui->a2->setFocus();

}

if(f2)

{

focusNextChild();

ui->a1->setFocus();

}

}

}

}

return QWidget::eventFilter(watched,event); //最后将事件交给上层对话框

}

左键功能定义稍加修改即可



2.实现动态焦点背景色变化功能

if (watched==ui->a1) //

{

if (event->type()==QEvent::FocusIn) //然后再判断控件的具体事件(这里指获得焦点事件)

{

QPalette p=QPalette();

p.setColor(QPalette::Button,Qt::yellow);

ui->a1->setPalette(p);

}

另一种实现方法

另外一般的焦点切换还可以使用setCurrentItem函数实现，下面是在网上看到的代码：

bool MainForm::eventFilter(QObject *obj,QEvent *event)

{

if(obj==ComboBox_Keyboard){

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

{

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

if(keyEvent->key()== 4100)//ENTER

on_ComboBox_Keyboard(ComboBox_Keyboard->currentItem());

if(keyEvent->key()== 4117){//DOWN

if(ComboBox_Keyboard->currentItem()==ComboBox_Keyboard->count()-1)

ComboBox_Keyboard->setCurrentItem(0);

else

ComboBox_Keyboard->setCurrentItem(ComboBox_Keyboard->currentItem()+1);}

if(keyEvent->key()== 4115){//UP

if(ComboBox_Keyboard->currentItem()==0)

ComboBox_Keyboard->setCurrentItem(ComboBox_Keyboard->count()-1);

else

ComboBox_Keyboard->setCurrentItem(ComboBox_Keyboard->currentItem()-1);}

returnTRUE;

}else{

returnFALSE;

}

}

…………

}



参考资料:

http://zoreraul.blog.163.com/blog/static/725739282010828104621410/

http://zhidao.baidu.com/link?url=4DCT55CnwXzT1nC28f0oPb36rrlK7bp0eohV61gtlZY0IvzLucMRqMvIjNHq4Oc5_horjUhyDkeSy0A1VYW7hK