學習實現計算器中，點選一個lineEdit後，再點選數字按鈕，可以將資料或符號顯示在選定的lineEdit中。

booleventFilter(QObject*,QEvent*);

MainWindow::MainWindow(QWidget*parent):

QMainWindow(parent),

ui(newUi::MainWindow)

{

ui->setupUi(this);

m_iCalFlag=0;

m_editFlag=0;

ui->firstLineEdit->installEventFilter(this);

ui->secondLineEdit->
 
installEventFilter(this);

ui->zeroButton->setFocusPolicy(Qt::NoFocus);

ui->oneButton->setFocusPolicy(Qt::NoFocus);

ui->twoButton->setFocusPolicy(Qt::NoFocus);

//QWidget::setFocusPolicy(Qt::NoFocus);

//QPushButton::setFocusPolicy(Qt::NoFocus);

//this->setFocusPolicy(Qt::NoFocus);

}

/* 判斷焦點位置 */

boolMainWindow::eventFilter(QObject*watched,QEvent*event)

{

if(watched==ui->firstLineEdit)

{

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

{

QPalettep=QPalette();

p.setColor(QPalette::Base,Qt::green);

ui->firstLineEdit->setPalette(p);

printf("getfirstfocusin\r\n");

m_editFlag=1;

}

elseif(event->type()==QEvent
 
::FocusOut)

{

QPalettep=QPalette();

p.setColor(QPalette::Base,Qt::white);

ui->firstLineEdit->setPalette(p);

printf("getfirstfocusout\r\n");

m_editFlag=0;

}

}

elseif(watched==ui->secondLineEdit)

{

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

{

QPalettep=QPalette();

p.setColor(QPalette::Base,Qt::green);

ui->secondLineEdit->setPalette(p);

printf("gettwofocusin\r\n");

m_editFlag=2;

}

elseif(event->type()==QEvent::FocusOut)

{

QPalettep=QPalette();

p.setColor(QPalette::Base,Qt::white);

ui->secondLineEdit->setPalette(p);

printf("gettwofocusout\r\n");

m_editFlag=0;

}

}

returnQWidget::eventFilter(watched,event);

}

單個控制元件分別設定焦點為無焦點即可。

Qt::TabFocus0x1the widget accepts focus by tabbing.
Qt::ClickFocus0x2the widget accepts focus by clicking.
Qt::StrongFocusTabFocus | ClickFocus | 0x8the widget accepts focus by both tabbing and clicking. On OS X this will also be indicate that the widget accepts tab focus when in 'Text/List focus mode'.
Qt::WheelFocusStrongFocus | 0x4like Qt::StrongFocus plus the widget accepts focus by using the mouse wheel.
Qt::NoFocus0 the widget does not accept focus.

嘗試了所有的pushbotton一個介面禁用，但是失敗了。

在ui介面設定屬性中直接設定更方便。

選中控制元件，在右側屬性欄中找到QWidget->focusPolicy->選擇NoFocus，則此控制元件不產生焦點。