雜記

主要參考網址: http://rritw.com/a/bianchengyuyan/C__/20120802/197558.html

參考網址: http://openhome.cc/Gossip/Qt4Gossip/EventFilter.html

測試程式 :

--------------------- myDialog.h ---------------------

class myDialog:publicQDialog

{

Q_OBJECT

public:

myDialog(QWidget*parent);

// ...省略...

private:
(自行重新定義按鍵事件的接收, 印出訊息)

void keyPressEvent(QKeyEvent*inEvent);

void keyReleaseEvent(QKeyEvent*inEvent);

// ...省略...

};

--------------------- myDialog.cpp ---------------------

// ...建構子等省略...

void myDialog::keyPressEvent(QKeyEvent*inEvent)

{

qDebug("ipcMsgKeyPressEvent!!!!!!!!!!!!");

}

void myDialog::keyReleaseEvent(QKeyEvent*inEvent)

{

qDebug("ipcMsgKeyReleaseEvent!!!!!!!!!!!!");

}

--------------------- MainWindow.h ---------------------

class MainWindow:public QMainWindow

{

Q_OBJECT

public:

explicit MainWindow(QWidget *parent=0);
// ...省略...

public slots:

int Show_myDialog();

// ...省略...

private:

bool eventFilter(QObject*,QEvent*);

myDialog *m_Msg;

// ...省略...
}

--------------------- MainWindow.cpp ---------------------

// 建構子等省略

int MainWindow::Show_myDialog()

{

m_Msg=new myDialog(0);

m_Msg->installEventFilter(this);

m_Msg->exec();

delete m_Msg;

m_Msg=NULL;
}




== case 1 : 設定如果接收到事件的是 m_Msg, 則會進入 eventFilter 並且傳遞此事件給m_Msg

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

{

if(obj==m_Msg)

{

qDebug("eventFilterreturn0!!!!!!!!!!!!");

return false;

}

}

執行, 按下按鍵印出的結果為: 

eventFilter return 0 !!!!!!!!!!!!
eventFilter return 0 !!!!!!!!!!!!
ipcMsg Key Press Event!!!!!!!!!!!!
eventFilter return 0 !!!!!!!!!!!!
ipcMsg Key Release Event!!!!!!!!!!!!
eventFilter return 0 !!!!!!!!!!!!

== case 2 : 設定如果接收到事件的是 m_Msg, 則會進入 eventFilter 並且會擋住事件不傳遞給m_Msg

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

{

if(obj==m_Msg)

{

qDebug("eventFilterreturn1!!!!!!!!!!!!");

return true;

}

else

{

qDebug("eventFilterreturn0!!!!!!!!!!!!");

return false;

}

}

執行, 按下按鍵印出的結果為: 

eventFilter return 1 !!!!!!!!!!!!

eventFilter return 1 !!!!!!!!!!!!

eventFilter return 1 !!!!!!!!!!!!

eventFilter return 1 !!!!!!!!!!!!

且發現除非是m_Msg正在執行中, 才會進入MainWindow的eventFilter函式
否則皆不會印出eventFilter裡面的任何訊息.