event filters : Signal « Qt « C++

1. C++
2. Qt
3. Signal

event filters

  

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#ifndef FILTEROBJECT_H
#define FILTEROBJECT_H

#include <QObject>

class FilterObject : public QObject
{
    Q_OBJECT

public:
    FilterObject(QObject *parent = 0);
    bool eventFilter(QObject *object, QEvent *event);
    void setFilteredObject(QObject *object);

private:
    QObject *target;
};

#endif









#include <QtGui>

#include "filterobject.h"

FilterObject::FilterObject(QObject *parent)
    : QObject(parent), target(0)
{
}

bool FilterObject::eventFilter(QObject *object, QEvent *event)
{
    if (object == target && event->type() == QEvent::KeyPress) {
        QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);
        if (keyEvent->key() == Qt::Key_Tab) {
            // Special tab handling
            return true;
        } else
            return false;
    }
    return false;
}

void FilterObject::setFilteredObject(QObject *object)
{
    if (target)
        target->removeEventFilter(this);

    target = object;

    if (target)
        target->installEventFilter(this);
}









#include <QApplication>
#include <QTextEdit>

#include "filterobject.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QTextEdit editor;
    FilterObject filter;
    filter.setFilteredObject(&editor);
    editor.show();
    return app.exec();
}

   
    
  

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