qt 5.15.2 主窗体事件及绘制功能

#include "mainwindow.h"

#include &lt;QApplication&gt;

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.setFixedWidth(600);
    w.setFixedHeight(600);
    w.show();
    //w.showMaximized(); //最大化显示后，再添加布局部件
    return a.exec();
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include &lt;QMainWindow&gt;

QT_BEGIN_NAMESPACE
namespace Ui {
class MainWindow;
}
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
    //
    void print(QString msg);
    void DrawBorad();
    void DrawTipText();
    void PrintMsg(int x,int y,QString msg);
    void line(int x1,int y1,int x2,int y2);
    void circle(int x,int y,int radius);
    //qt 绘制事件
    void paintEvent(QPaintEvent *event);
    //qt mouse event
    void mousePressEvent(QMouseEvent *event);
    void mouseReleaseEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    void keyPressEvent(QKeyEvent *event);
    void wheelEvent(QWheelEvent *event);
    void resizeEvent(QResizeEvent *event);


    //
    void DrawPiece();

private:
    Ui::MainWindow *ui;    
    bool isMousePressed=false;
    QPoint currentPoint;
    char Current_piece='O';
    //初始化
    char Board_piece[3][3]=
    {
        {'_','_','_'},
        {'_','_','o'},
        {'_','_','x'}
    };
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <qpainter.h>
#include <iostream>
#include <QDebug>
#include <QMouseEvent>
#include <QKeyEvent>
#include <QWheelEvent>
#include <QResizeEvent>


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    //mouse move event setup must two line OK
    this->setMouseTracking(true);
    ui->centralwidget->setMouseTracking(true);
    //
}

MainWindow::~MainWindow()
{
    delete ui;    
}

void MainWindow::print(QString msg)
{
    qDebug()<<msg;
    //std:cout<<msg.toStdString()<<std::endl;
}

void MainWindow::DrawBorad()
{
    line(0,200,600,200);   //c
    line(0,400,600,400);   //d
    line(200,0,200,600);  //a
    line(400,0,400,600);   //b
}

void MainWindow::line(int x1,int y1,int x2,int y2)
{
    QPainter painter(this);
    painter.drawLine(x1,y1,x2,y2);
}

void MainWindow::circle(int x,int y,int radius)
{
    QPainter painter(this);
    painter.drawEllipse(QPoint(x,y),radius,radius);
}


void MainWindow::DrawTipText()
{
    QPainter painter(this);
    //static TCHAR str[64];
    //_stprintf_s(str,_T("当前棋子类型:%c"),Current_piece);
    //settextcolor(RGB(255,175,45));
    //outtextxy(0,0,str);
    QPen pen;
    pen.setWidth(2);//设置线宽
    pen.setStyle(Qt::SolidLine);//样式
    pen.setColor(QColor(255,0,0));//文字颜色
    painter.setPen(pen);
    QString msg=QString::asprintf("当前棋子类型:%c",Current_piece);
    painter.drawText(10, 15, msg);//文本内容
}

void MainWindow::PrintMsg(int x,int y,QString msg)
{
    QPainter painter(this);
    //static TCHAR str[64];
    //_stprintf_s(str,_T("当前棋子类型:%c"),Current_piece);
    //settextcolor(RGB(255,175,45));
    //outtextxy(0,0,str);
    QPen pen;
    pen.setWidth(2);//设置线宽
    pen.setStyle(Qt::SolidLine);//样式
    pen.setColor(QColor(255,45,100));//文字颜色
    painter.setPen(pen);
    painter.drawText(x, y, msg);//文本内容
}

void MainWindow::DrawPiece()
{
    for(int i=0;i<3;i++)
    {
        for(int j=0;j<3;j++)
        {
            switch(this->Board_piece[i][j])
            {
              case 'O':
              case 'o':
                this->circle(200*j+100,200*i+100,100);
                break;
              case 'x':
              case 'X':
              {
                  int x=200*j;
                  int y=200*i;
                  line(x,y,x+200,y+200);   //左对角线(x,y)-(x+100,y+100)
                  line(x+200,y,x,y+200);   //右对角线(x+100,y)-(x,y+100)
              }
              break;
              case '_':
              case '-':
                  break;
            }
        }
    }
}

//总绘制事件
void MainWindow::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    //反走样
    painter.setRenderHint(QPainter::Antialiasing, true);
    //画背景图

    QString jpgPath="E:\cwgis_qt\hsg\qi_three_son\images\china_hdz.jpg";

    painter.drawPixmap(0,0, 600, 600, QPixmap(jpgPath));

    //定义画笔
    QPen pen;
    pen.setWidth(2);//设置线宽
    pen.setColor(QColor(222,255,55));//颜色
    pen.setStyle(Qt::SolidLine);//样式
    //画刷
    QBrush brush;
    brush.setColor(Qt::black);//颜色
    brush.setStyle(Qt::SolidPattern);//样式
    //设置画笔画刷
    painter.setPen(pen);
    painter.setBrush(brush);
    //画直线
    painter.drawLine(50,50,150,50);
    painter.drawLine(20,50,250,150 );
    //画矩形
    painter.drawRect(70,200,100,50);
    //画椭圆
    painter.drawEllipse(QPoint(270,150),50,80);

    //画文字
    QFont font;
    font.setFamily("MV Boli");//文字字体
    font.setPixelSize(20);//文字大小
    pen.setColor(QColor(255,55,255));//文字颜色
    painter.setFont(font);
    painter.setPen(pen);
    painter.drawText(200, 300, "Qt Creator 12.0.0 (opensource)");//文本内容
    //
    this->DrawBorad();
    this->DrawPiece();
    //
    this->DrawTipText();
    this->PrintMsg(20,30,jpgPath);
    this->PrintMsg(20,40,qApp->applicationDirPath());  //获取可执行文件所在目录
    //
    {
       QString msg=QString::asprintf("%d,%d",this->currentPoint.x(),this->currentPoint.y());
       this->PrintMsg(40,580,"(x,y)="+msg);
    }
}

void MainWindow::mousePressEvent(QMouseEvent *event)
{
    this->isMousePressed=true;
    print("pressed mouse");
    this->update();
}
void MainWindow::mouseReleaseEvent(QMouseEvent *event)
{
    this->isMousePressed=false;
    print("unpresse mouse");
    this->update();
}

void MainWindow::mouseMoveEvent(QMouseEvent *event)
{
    QPoint p=event->pos();
    this->currentPoint=p;
    qDebug()<<"pos="<<p;   //需要引用#include <QMouseEvent>
    //QString msg=QString::asprintf("%d,%d",p.x(),p.y());
    //this->PrintMsg(40,300,"(x,y)="+msg);
    //qDebug()<<msg;
    if(this->isMousePressed)
    {
        QString msg=QString::asprintf("%b",this->isMousePressed);
        this->PrintMsg(570,40,"isMousePressed="+msg);

    }
    else
    {
        QString msg=QString::asprintf("%b",this->isMousePressed);
        this->PrintMsg(570,40,"isMousePressed="+msg);
    }
    print("moveing mouse");
    this->update();   //更新触发重绘事件paintEvent 才能动态显示当前点坐标(x,y)=100,200
}

void MainWindow::keyPressEvent(QKeyEvent *event)
{
    qDebug()<<"key: "<<event->key();
    this->update();
}
void MainWindow::wheelEvent(QWheelEvent *event)
{
    qDebug()<<"wheel: "<<event->angleDelta();
    this->update();
}

void MainWindow::resizeEvent(QResizeEvent *event)
{
    qDebug()<<"resize: "<<event->size();
    this->update();
}