Qt5学习笔记（消息基础）

  1 #include "MyWidget.h"
  2 #include <QApplication>
  3 #include <QEvent>
  4 #include <QDebug>
  5 #include <QMouseEvent>//子类
  6 #include <QKeyEvent>
  7 #include <QVBoxLayout>
  8 
  9 MyWidget::MyWidget(QWidget *parent) : QWidget(parent)
 10 {
 11     QVBoxLayout* lay = new QVBoxLayout(this);
 12 #if 0
 13     QPushButton* button2;
 14     lay->addWidget(button = new QPushButton("OK", this));
 15     lay->addWidget(button2 = new QPushButton("Button2"));
 16     //按钮接收键盘信息，而不仅是鼠标
 17     button->setDefault(true);//空格键
 18     this->setMouseTracking(true);//鼠标不需要按住，mouseMove就能得到调用
 19 
 20     connect(button, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));//单击，接收信号
 21     connect(button2, SIGNAL(clicked()), this, SLOT(slotButtonClicked()));
 22 #endif
 23     lay->addWidget(edit = new QLineEdit());
 24     connect(edit, SIGNAL(returnPressed()),this ,SLOT(slotButtonClicked()));
 25 }
 26 void MyWidget::slotButtonClicked()//槽函数
 27 {
 28     //QPushButton* button =  (QPushButton*)sender();
 29     QLineEdit* button =  (QLineEdit*)sender();
 30     qDebug() << button->text();//可以知道那个按钮被操作
 31 }
 32 /* 任何信息都是QApplication先得到－》具体应该处理的窗口：：event()->event()根据信息类型来调用具体的虚函数*/
 33 /* 1)可以重载具体的虚函数，来实现对消息的响应
 34  * ２）可以重载ｅｖｅｎｔ函数，用来处理或者截取消息*/
 35 /*截取消息*/
 36 bool MyWidget::event(QEvent *ev) //重载event函数
 37 {
 38     /*
 39     if (ev->type() == QEvent::MouseButtonPress)  //
 40     {
 41         QMouseEvent* ev1 = (QMouseEvent*)ev;　//强制类型转换QEvent 转　QMouseEvent
 42         qDebug() << "mouse press";
 43     }
 44     */
 45     //if(ev->type() == QEvent::MouseButtonPress)//截断
 46     //    return true;
 47     ev->accept();
 48 
 49     return QWidget::event(ev);//父类的虚函数
 50 }
 51 
 52 void MyWidget::closeEvent(QCloseEvent *)//关闭窗口后发送
 53 {
 54     qDebug() << "closeEvent";
 55 }
 56 
 57 void MyWidget::mousePressEvent(QMouseEvent *ev)
 58 {
 59 #if 0
 60     QPoint pt = ev->pos();
 61     qDebug() << pt;
 62     if (ev->button() == Qt::LeftButton)
 63     {
 64 
 65     }
 66     if (ev->modifiers() == Qt::ShiftModifier)
 67     {
 68         qDebug() << "shift press";
 69     }
 70 #endif
 71     if(ev->button() == Qt::LeftButton)//左键
 72     {
 73         if (ev->modifiers()==Qt::ControlModifier)//ctrl
 74         {
 75             return;
 76         }
 77     }
 78     else
 79     {}
 80 }
 81 void MyWidget::mouseReleaseEvent(QMouseEvent *)
 82 {}
 83 void MyWidget::mouseMoveEvent(QMouseEvent *)
 84 {
 85     static int i = 0;
 86     qDebug() << "mouse move"<<i++;
 87 }
 88 void MyWidget::keyPressEvent(QKeyEvent *ev)
 89 {
 90     ev->modifiers();
 91     int key = ev->key();
 92     qDebug() << key;
 93     char a = key;
 94     qDebug() << (char)a;
 95 }
 96 void MyWidget::keyReleaseEvent(QKeyEvent *)
 97 {}
 98 int main(int argc, char* argv[])
 99 {
100     QApplication app(argc, argv);
101     MyWidget w;
102     w.show();
103 
104     return app.exec();
105 }

 1 #ifndef MYWIDGET_H
 2 #define MYWIDGET_H
 3 
 4 #include <QWidget>
 5 #include <QPushButton>
 6 #include <QLineEdit>
 7 class MyWidget : public QWidget
 8 {
 9     Q_OBJECT
10 public:
11     explicit MyWidget(QWidget *parent = nullptr);
12 
13     /* widget's event handler (all event) */
14     bool event(QEvent *);//函数原型
15 
16     void mousePressEvent(QMouseEvent *);
17     void mouseReleaseEvent(QMouseEvent *);
18     void mouseMoveEvent(QMouseEvent *);
19     /*不要用*/
20     //void mouseDoubleClickEvent(QMouseEvent *);
21 
22     void keyPressEvent(QKeyEvent *);
23     void keyReleaseEvent(QKeyEvent *);
24 
25     void closeEvent(QCloseEvent *);
26 
27     //void showEvent(QShowEvent *);
28     //void hideEvent(QHideEvent *);
29 
30     QPushButton* button;
31     QLineEdit* edit;
32 
33 signals:
34 
35 public slots:
36     void slotButtonClicked();
37 };
38 
39 #endif // MYWIDGET_H

HEADERS += \
    MyWidget.h

SOURCES += \
    MyWidget.cpp

QT += widgets gui

一部分关于按钮消息，另一部分关于文本输入。