Qt事件处理练习（20200216）

怼烎@ 2023-07-06 06:17 54阅读 0赞

#include "widget.h"
    
    Widget::Widget(QWidget *parent)
        : QWidget(parent)
    {
       m_canvasPix = QPixmap(this->width(),this->height());
       m_canvasPix.fill(Qt::white);
       m_bIsDrawing = false;
       m_timerId1 = startTimer(1000);
       m_timerId2 = startTimer(1000);
       m_timerId3 = startTimer(1000);
    
       QTimer *timer = new QTimer(this);
       connect(timer,SIGNAL(timeout()),this,SLOT(updateTimer()));
       timer->start(1000);
    }
    
    Widget::~Widget()
    {
    
    }
    
    void Widget::updateTimer()
    {
        qDebug("style 1: hello world .....");
    }
    
    void Widget::paintEvent(QPaintEvent *event)
    {
        int x,y,w,h;
        x = m_lastPt.x();
        y = m_lastPt.y();
        w = m_endPt.x() - x;
        h = m_endPt.y() - y;
        QPainter painter(this);
        //! 如果正在绘图，就在辅助画布上绘制
        if(m_bIsDrawing)
        {
            //! 将以前pix中的内容复制到tempPix中，保证以前的内容不消失
            m_tmpCanvasPix = m_canvasPix;
            QPainter pp(&m_tmpCanvasPix);
            pp.drawRect(x,y,w,h);
            painter.drawPixmap(0, 0, m_tmpCanvasPix);
        } else {
            QPainter pp(&m_canvasPix);
            pp.drawRect(x,y,w,h);
            painter.drawPixmap(0,0,m_canvasPix);
        }
    }
    
    void Widget::mousePressEvent(QMouseEvent *event)
    {
        if (event->button() == Qt::LeftButton){
            m_lastPt = event->pos();
            m_bIsDrawing = true;   //正在绘图
        }
    }
    
    void Widget::mouseReleaseEvent(QMouseEvent *event)
    {
        if (event->button() == Qt::LeftButton){
            m_endPt = event->pos();
            m_bIsDrawing = false;
            update();
        }
    
    }
    
    void Widget::mouseMoveEvent(QMouseEvent *event)
    {
        if (event->buttons() == Qt::LeftButton){
            m_endPt = event->pos();
            update();
        }
    
    }
    
    void Widget::keyPressEvent(QKeyEvent *event)
    {
        int x,y;
        if (event->modifiers() == Qt::ControlModifier) {
            switch (event->key()) {
            case Qt::Key_Down:
                x = m_endPt.x()+10;
                y = m_endPt.y()+10;
                m_endPt.setX(x);
                m_endPt.setY(y);
                update();
                m_bIsDrawing = true;
                break;
            case Qt::Key_Up:
                x = m_endPt.x()-10;
                y = m_endPt.y()-10;
                m_endPt.setX(x);
                m_endPt.setY(y);
                update();
                m_bIsDrawing = true;
                break;
            }
        }
    }
    
    void Widget::keyReleaseEvent(QKeyEvent *event)
    {
        switch (event->key()) {
        case Qt::Key_Down:
            m_bIsDrawing = false;
            update();
            break;
        case Qt::Key_Up:
            m_bIsDrawing = false;
            update();
            break;
    
        }
    }
    
    void Widget::timerEvent(QTimerEvent *event)
    {
        if (event->timerId() == m_timerId1) {
            qDebug("style 2:timerId %d,hello world...",event->timerId());
        }
        else if (event->timerId() == m_timerId2){
            qDebug("style 2:timerId %d,hello world...",event->timerId());
        }
        else if (event->timerId() == m_timerId3){
            qDebug("style 2:timerId %d,hello world...",event->timerId());
        }
    }

#ifndef WIDGET_H
    #define WIDGET_H
    
    #include <QWidget>
    #include <QPushButton>
    #include <qlayout.h>
    #include <QPainter>
    #include <QMouseEvent>
    #include <QKeyEvent>
    #include <QTimer>
    #include <QTime>
    #include <QTimerEvent>
    
    class Widget : public QWidget
    {
        Q_OBJECT
    
    public:
        Widget(QWidget *parent = 0);
        ~Widget();
    
    private:
        QPixmap m_canvasPix;
        QPoint  m_lastPt;
        QPoint  m_endPt;
        QPixmap m_tmpCanvasPix;    //! 辅助画布
        bool    m_bIsDrawing;      //! 标志是否正在绘图
        int     m_timerId1;        //! 定时器1
        int     m_timerId2;        //! 定时器2
        int     m_timerId3;        //! 定时器3
    private slots:
        void updateTimer();
    protected:
        void paintEvent(QPaintEvent *event);
        void mousePressEvent(QMouseEvent *event);
        void mouseReleaseEvent(QMouseEvent *event);
        void mouseMoveEvent(QMouseEvent *event);
        void keyPressEvent(QKeyEvent *event);
        void keyReleaseEvent(QKeyEvent *event);
        void timerEvent(QTimerEvent *event);
    };
    
    #endif // WIDGET_H

#ifndef MYAPPLICATION_H
    #define MYAPPLICATION_H
    #include<QApplication>
    #include<QMouseEvent>
    #include<QDebug>
    
    class myApplication : public QApplication
    {
    public:
        myApplication(int argc, char *argv[]);
    
    protected:
        bool eventFilter(QObject *obj, QEvent *event);
    };
    
    #endif // MYAPPLICATION_H

#include "myapplication.h"
    
    myApplication::myApplication(int argc, char *argv[]):QApplication(argc,argv)
    {
    
    }
    
    bool myApplication::eventFilter(QObject *obj, QEvent *event)
    {
        static int k=1;
        if(event->type()==QEvent::MouseButtonPress||event->type()==QEvent::MouseButtonDblClick)
        {
            qDebug()<<"Click"<<k;
            k++;
            return true;
        }
        return QApplication::eventFilter(obj,event);
    
    }

#include "widget.h"
    #include "myapplication.h"
    #include <QApplication>
    
    int main(int argc, char *argv[])
    {
        myApplication a(argc, argv);
        a.installEventFilter(&a);
        Widget w;
        w.show();
    
        return a.exec();
    }

![20200216191123312.png][]

[20200216191123312.png]: https://img-blog.csdnimg.cn/20200216191123312.png