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新建一个项目：06Event
新建cpp文件
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06Event.pro |
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HEADERS MyWidget.h SOURCES MyWidget.cpp QT |
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MyWidget.h |
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#ifndef #define #include #include #include class { Q_OBJECT public: explicit bool void void void /*不要用,因为它默认调用两次mousePressEvent*/ //void void void void //void //void void QPushButton* QLineEdit* signals: public void }; #endif |
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MyWidget.cpp |
#include "MyWidget.h" #include <QApplication> #include <QEvent> #include <QDebug> #include <QMouseEvent> #include <QKeyEvent> #include <QVBoxLayout> #include <QPainter> MyWidget::MyWidget(QWidget *parent) : QWidget(parent) {
// QVBoxLayout* lay = new QVBoxLayout(this); #if 0 QPushButton* button2; lay->addWidget(button = new QPushButton("OK", this));
lay->addWidget(button2 = new QPushButton("Button2"));
//设置它为默认的焦点，当点击tab键之后可以切换焦点 button->setDefault(true); // 鼠标不需要按下，mouseMove就能得到调用 this->setMouseTracking(true); connect(button2, SIGNAL(clicked()), this, SLOT(slotButtonClicked())); connect(button, SIGNAL(clicked()), this, SLOT(slotButtonClicked())); #endif // lay->addWidget(edit = new QLineEdit()); // connect(edit, SIGNAL(returnPressed()), this, SLOT(slotButtonClicked())); } //通过这一句实现点击按钮的时候获得按钮上的text()内容 void MyWidget::slotButtonClicked() {
QLineEdit* button = (QLineEdit*)sender(); qDebug() << button->text(); } /* QApplication先得到->具体应该处理的窗口::event()->event()根据消息类型来调用具体的虚函数 */ /* 1）可以重载具体的虚函数，来实现对消息的响应 2）可以重载event函数，用来处理或者截取消息 */ /* 截取消息 */ bool MyWidget::event(QEvent *ev) {
// 鼠标消息被截断 // if(ev->type() == QEvent::MouseButtonPress) // return true; ev->accept(); return QWidget::event(ev); } /** * @brief MyWidget::closeEvent 窗口关闭的事件 */ void MyWidget::closeEvent(QCloseEvent *) {
qDebug() << "closeEvent"; } void MyWidget::paintEvent(QPaintEvent *) {
QPainter p(this); //通过下面的方式实现画线 p.drawLine(QPoint(0, 0), QPoint(100, 100)); } /** * @brief MyWidget::mousePressEvent 鼠标按下的事件 * @param ev */ void MyWidget::mousePressEvent(QMouseEvent *ev) {
#if 0 QPoint pt = ev->pos(); qDebug() << pt; //如果鼠标按下的是左键的处理 if(ev->button() == Qt::LeftButton){}
//如果按下的Shift键了 if(ev->modifiers() == Qt::ShiftModifier) {
qDebug() << "shift press"; } #endif //改进办法：先判断是否有左键，然后如果判断是否还按了Ctrl键 if(ev->button() == Qt::LeftButton) {
if(ev->modifiers() == Qt::ControlModifier) {
// handle with Control; return; } // handle2 without control; } else {}
} /** * @brief MyWidget::mouseReleaseEvent 鼠标释放的按键 */ void MyWidget::mouseReleaseEvent(QMouseEvent *){}
/** * @brief MyWidget::mouseMoveEvent 鼠标移动的事件 */ void MyWidget::mouseMoveEvent(QMouseEvent *) {
static int i=0; qDebug() << "mouse move"<< i++; } /** * @brief MyWidget::keyPressEvent 鼠标按下的事件，通过这个可以获得按下的键 * @param ev */ void MyWidget::keyPressEvent(QKeyEvent *ev) {
ev->modifiers(); int key = ev->key(); qDebug() << key; char a = key; qDebug() << (char)a; } /** * @brief MyWidget::keyReleaseEvent 按键释放的事件 */ void MyWidget::keyReleaseEvent(QKeyEvent *){}
int main(int argc, char* argv[]) {
QApplication app(argc, argv); MyWidget w; w.show(); return app.exec(); } |
运行结果： |
2
QT消息过滤器
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EventFilter.pro |
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HEADERS MyWidget.h MyApplication.h SOURCES MyWidget.cpp MyApplication.cpp QT |
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MyWidget.h |
#ifndef MYWIDGET_H #define MYWIDGET_H #include <QWidget> #include <QPushButton> class MyWidget : public QWidget {
Q_OBJECT public: explicit MyWidget(QWidget *parent); QPushButton* _button; bool eventFilter(QObject *, QEvent *); bool event(QEvent *); signals: public slots: }; #endif // MYWIDGET_H |
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MyWidget.cpp |
#include "MyWidget.h" #include <QPushButton> #include <QEvent> #include "MyApplication.h" #include <QDebug> #include <QApplication> MyWidget::MyWidget(QWidget *parent) : QWidget(parent) {
QPushButton* button; button = new QPushButton("This button", this);
connect(button, SIGNAL(clicked()), this, SLOT(close())); _button = button; /*button给自己安装了一个消息过滤器，那么经过button的消息， * 都先要调用它的过滤器的eventFilter函数*/ button->installEventFilter(this); } bool MyWidget::eventFilter(QObject *o, QEvent *e) {
#if 0 if(0 == (QObject*)_button &&( e->type() == QEvent::MouseButtonRelease || e->type() == QEvent::MouseButtonDblClick || e->type() == QEvent::MouseButtonPress)) {
return true; } #endif return QWidget::eventFilter(o,e); } bool MyWidget::event(QEvent *e) {
if(e->type() == QEvent::User) {
qDebug() << "User event is comming"; } return QWidget::event(e); } int main(int argc,char *argv[]) {
MyApplication app(argc,argv); MyWidget w; w.show(); //发送一个Event给MyWidget qDebug() << "begin send"; app.postEvent(&w,new QEvent(QEvent::User)); qDebug() << "end send"; return app.exec(); } |
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MyApplication.h |
#ifndef MYAPPLICATION_H #define MYAPPLICATION_H #include <QApplication> class MyApplication : public QApplication {
Q_OBJECT public: MyApplication(int argc,char *argv[]):QApplication(argc,argv) {}
bool notify(QObject *,QEvent *); signals: public slots: }; #endif // MYAPPLICATION_H |
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MyApplication.cpp |
#include "MyApplication.h" #include <QEvent> #include <QDebug> bool MyApplication::notify(QObject *o, QEvent *e) {
if(this->topLevelWidgets().count()>0) {
QWidget* mainWnd = this->topLevelWidgets().at(0); if(o==(QObject*)mainWnd && e->type() == QEvent::MouseButtonPress) {
// do ... qDebug() << "mainwnd is clicked"; } } return QApplication::notify(o, e); } |
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运行结果：
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