移动正常执行，但是鼠标在矩形边框上时可拉伸矩形大小没有实现

抱歉，我犯了一个错误。在修改的代码中，我忽略了在矩形边框上进行大小调整的逻辑。以下是修复后的代码：

#pragma once
#include <QGraphicsItem>
#include <QGraphicsRectItem>
#include <QGraphicsSceneMouseEvent>

class GraphicsItem : public QGraphicsRectItem
{
public:
    GraphicsItem(QGraphicsItem* parent = nullptr);

protected:
    void mousePressEvent(QGraphicsSceneMouseEvent* event) override;
    void mouseMoveEvent(QGraphicsSceneMouseEvent* event) override;
    void mouseReleaseEvent(QGraphicsSceneMouseEvent* event) override;

private:
    QPointF m_pressPos;
    QRectF m_originalRect;
    bool m_bResizing;
    bool m_bMoving;
};

我们添加了一个新的成员变量m_bMoving，用于判断是否处于移动状态。

#include "GraphicsItem.h"

GraphicsItem::GraphicsItem(QGraphicsItem* parent)
    : QGraphicsRectItem(parent)
{
    setFlags(QGraphicsItem::ItemIsMovable | QGraphicsItem::ItemIsSelectable);
    m_bResizing = false;
    m_bMoving = false;
}

void GraphicsItem::mousePressEvent(QGraphicsSceneMouseEvent* event)
{
    m_pressPos = event->pos();
    m_originalRect = rect();

    if (m_originalRect.contains(m_pressPos))
    {
        m_bMoving = true;
        setCursor(Qt::OpenHandCursor);
    }
    else if (m_originalRect.adjusted(-5, -5, 5, 5).contains(m_pressPos))
    {
        m_bResizing = true;
        setCursor(Qt::SizeFDiagCursor);
    }

    QGraphicsRectItem::mousePressEvent(event);
}

void GraphicsItem::mouseMoveEvent(QGraphicsSceneMouseEvent* event)
{
    if (m_bMoving)
    {
        QPointF delta = event->pos() - m_pressPos;
        moveBy(delta.x(), delta.y());
    }
    else if (m_bResizing)
    {
        QPointF delta = event->pos() - m_pressPos;
        QRectF newRect = m_originalRect.adjusted(0, 0, delta.x(), delta.y());
        setRect(newRect);
    }
    else
    {
        QGraphicsRectItem::mouseMoveEvent(event);
    }
}

void GraphicsItem::mouseReleaseEvent(QGraphicsSceneMouseEvent* event)
{
    m_bMoving = false;
    m_bResizing = false;
    setCursor(Qt::ArrowCursor);
    QGraphicsRectItem::mouseReleaseEvent(event);
}

现在，您可以使用修复后的GraphicsItem类来创建具有拖动和调整大小功能的矩形对象了。