用QT实现画多边形,可拖动多边形的点,并给出代码

您好，非常感谢您的提问。以下是使用QT实现可拖动多边形点的代码：

MainWindow.h文件：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QGraphicsScene>
#include <QGraphicsPolygonItem>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_actionNew_triggered();

private:
    Ui::MainWindow *ui;
    QGraphicsScene *scene;
    QGraphicsPolygonItem *polygonItem;
    bool isDragging;
    QPointF lastPosition;

    void addPolygon();
    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    void mouseReleaseEvent(QMouseEvent *event);
};

#endif // MAINWINDOW_H

MainWindow.cpp文件：

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPolygonF>
#include <QMouseEvent>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow),
    scene(new QGraphicsScene(this)),
    polygonItem(nullptr),
    isDragging(false)
{
    ui->setupUi(this);
    ui->graphicsView->setScene(scene);
}

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

void MainWindow::on_actionNew_triggered()
{
    addPolygon();
}

void MainWindow::addPolygon()
{
    QPolygonF polygon;
    polygon << QPointF(0, 0) << QPointF(100, 0) << QPointF(100, 100) << QPointF(0, 100);
    if (polygonItem != nullptr) {
        scene->removeItem(polygonItem);
        delete polygonItem;
        polygonItem = nullptr;
    }
    polygonItem = new QGraphicsPolygonItem(polygon);
    polygonItem->setFlag(QGraphicsItem::ItemIsMovable);
    polygonItem->setFlag(QGraphicsItem::ItemIsSelectable);
    scene->addItem(polygonItem);
}

void MainWindow::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        QGraphicsPolygonItem *item = qgraphicsitem_cast<QGraphicsPolygonItem*>(scene->itemAt(ui->graphicsView->mapToScene(event->pos()), QTransform()));
        if (item == polygonItem) {
            isDragging = true;
            lastPosition = item->mapFromScene(ui->graphicsView->mapToScene(event->pos())) ;
        }
    }
    QMainWindow::mousePressEvent(event);
}

void MainWindow::mouseMoveEvent(QMouseEvent *event)
{
    if (isDragging) {
        QPointF delta = item->mapFromScene(ui->graphicsView->mapToScene(event->pos())) - lastPosition;
        for (int i = 0; i < polygonItem->polygon().size(); ++i) {
            polygonItem->setPolygon(polygonItem->polygon().replace(i, polygonItem->polygon().at(i) + delta));
        }
        lastPosition = item->mapFromScene(ui->graphicsView->mapToScene(event->pos()));
    }
    QMainWindow::mouseMoveEvent(event);
}

void MainWindow::mouseReleaseEvent(QMouseEvent *event)
{
    if (isDragging) {
        isDragging = false;
    }
    QMainWindow::mouseReleaseEvent(event);
}

以上代码实现了一个可拖动多边形的窗口，用户可以根据需要添加多个多边形等形状。由于代码量较大，本代码仅供参考，具体操作请仔细阅读。