最近做了个测试发现Qt 的eventFilter无法过滤mouse事件,如mouseMove, mousePress, mouseRelease等,
原来是installEventFilter(QObject *)安装不对。看Qt例子:
class MainWindow : public QMainWindow { public: MainWindow(); protected: bool eventFilter(QObject *obj, QEvent *ev); private: QTextEdit *textEdit; }; MainWindow::MainWindow() { textEdit = new QTextEdit; setCentralWidget(textEdit); textEdit->installEventFilter(this); } bool MainWindow::eventFilter(QObject *obj, QEvent *event) { if (obj == textEdit) { if (event->type() == QEvent::KeyPress) { QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event); qDebug() << "Ate key press" << keyEvent->key(); return true; } else { return false; } } else { // pass the event on to the parent class return QMainWindow::eventFilter(obj, event); } }
这里eventFilter接受的是QEvent::KeyPress事件,打印event->type发现始终获得不到mouse事件,
原来因为QTextEdit是由QAbstractScollArea派生的,对于QAbstractScollArea,其过滤器要安装在viewport上,
因此上面程序变换如下即可过滤mouse event:
class MainWindow : public QMainWindow { public: MainWindow(); protected: bool eventFilter(QObject *obj, QEvent *ev); private: QTextEdit *textEdit; }; MainWindow::MainWindow() { textEdit = new QTextEdit; setCentralWidget(textEdit); textEdit->installEventFilter(this); textEdit->viewPort->installEventFilter(this); } bool MainWindow::eventFilter(QObject *obj, QEvent *event) { if (obj == textEdit) { if (event->type() == QEvent::KeyPress) { QKeyEvent *keyEvent = static_cast<QKeyEvent*>(event); qDebug() << "Ate key press" << keyEvent->key(); return true; } else { return false; } } else if (obj == textEdit->viewPort()) { // To do..... if (event->type() == QEvent::mouseMove) { return true; } } else { // pass the event on to the parent class return QMainWindow::eventFilter(obj, event); } }