由于项目要求，需要加载svg格式图片和pixmap图片，并根据指定坐标在图上进行勾画，并且对相应位置接收鼠标事件。

-继承QGraphicsObject,实现加载pixmap的项

myimageitem.h

#ifndef MYIMAGEITEM_H
#define MYIMAGEITEM_H
#include
#include
#include
#include
#include

class myimageitem: public QGraphicsObject
{
Q_OBJECT
public:
myimageitem(QRectF, rect,const QPixmap &image,QGraphicsObject *parent = nullptr);//rect 项的边框尺寸，image 图像
~myimageitem();

void setRect(const QRectF &rect);

QRectF boundingRect()const override;  
void paint(QPainter \*panter, const QStyleOptionGraphicsItem \*option, QWidget \*widget) override;  

protected:
void mousePressEvent(QGraphicsSceneMouseEvent *event) override;
public slots:
void onSyn(int id);

signals:
void syn(int id);
private:
QRectF m_rect;
QPixmap m_pixmap;
float deltaX; // 显示窗口大小与实际图片横轴比例
float deltaY; // 显示窗口大小与实际图片竖轴比例
QMap _rectPointSelected;// 标记矩形是否被鼠标事件选中
QMap _rectPoint; // 保存矩形数据
};

#endif // MYIMAGEITEM_H

#include "myimageitem.h"

myimageitem::myimageitem(QRectF rect,const QPixmap &image, QGraphicsObject * parent):QGraphicsObject(parent),m_pixmap(image)
{
deltaX = rect.width()/m_pixmap.width();
deltaY = rect.height()/m_pixmap.height();
QRectF rect1(0,0,200*deltaX,200*deltaY);
QRectF rect2(200*deltaX, 200*deltaY, 200*deltaX, 200*deltaY);

　　// 初始化测试坐标数据
_rectPoint.insert(0, rect1);
_rectPointSelected.insert(0,false);
_rectPoint.insert(1,rect2);
_rectPointSelected.insert(1,false);
setRect(rect);
}
myimageitem::~myimageitem(){

}

void myimageitem::setRect(const QRectF &rect)
{
if(m_rect == rect){
return;
}
prepareGeometryChange();
m_rect = rect;
update(); // 通知重绘图片

}

QRectF myimageitem::boundingRect() const{
return m_rect; // 边界尺寸
}

void myimageitem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget){
Q_UNUSED(option);
Q_UNUSED(widget);

painter->setRenderHint(QPainter::Antialiasing, true); // 打开抗锯齿  
painter->save();  
painter->drawPixmap(m\_rect, m\_pixmap,QRectF()); // 画图

for(QMap<int, bool>::iterator it = \_rectPointSelected.begin(); it != \_rectPointSelected.end(); ++it){  
    if(!it.value()){  
        painter->setPen(Qt::blue); // 如果未被选中  
    }else {  
        painter->setPen(Qt::red); // 如果被选中  
        it.value() = false; // 重绘之后选中状态重置  
    }  
    painter->drawRect(\_rectPoint\[it.key()\]); // 绘制矩形  
}

painter->restore();  

}

void myimageitem::mousePressEvent(QGraphicsSceneMouseEvent *event){ // 接收鼠标事件
if(event->button() == Qt::LeftButton){
for(QMap::iterator it = _rectPoint.begin(); it != _rectPoint.end(); ++it){
if(it.value().contains(event->pos())){
prepareGeometryChange();// 保持项的索引，即使改变了项的尺寸，如果有必要会调用update()
_rectPointSelected[it.key()] = true; // 选中矩形
// emit syn(it.key());
}
}
}
}

void myimageitem::onSyn(int id){
prepareGeometryChange();
_rectPointSelected[id] = true;
update();
}

-继承QGraphicsSvgItem

mygriditem.h

_#ifndef MYGRIDITEM_H
#define MYGRIDITEM_H
#include
#include
#include
#include

class mygriditem :public QGraphicsSvgItem
{
_ Q_OBJECTpublic:
_mygriditem(QRectF boundRect,const QString &svgFile,const QSize svgSize,QGraphicsSvgItem *parent = nullptr);// 导入svg格式图片文件 和尺寸
~mygriditem();
QRectF boundingRect()const override;
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)override;

signals:
void syn(int id);
public slots:
void onSyn(int id);

protected:
void mousePressEvent(QGraphicsSceneMouseEvent *event) override;
private:
QRectF _boundRect; // 边界矩形_
_QSvgRenderer *_svgRender;
float _xDelta;
float _yDelta;
QMap _rectPointSelected;
QMap _rectPoint;
};

#endif // MYGRIDITEM_H_

#include "mygriditem.h"

mygriditem::mygriditem(QRectF boundRect,const QString &svgFile,const QSize svgSize ,QGraphicsSvgItem *parent):QGraphicsSvgItem(parent),
_boundRect(boundRect)
{
_svgRender = new QSvgRenderer(svgFile); //加载svg图

\_xDelta = \_boundRect.width()/svgSize.width();  
\_yDelta = \_boundRect.height()/ svgSize.height();

QRectF rect1(0\*\_xDelta,0\*\_yDelta,60\*\_xDelta,60\*\_yDelta);  
QRectF rect2(60\*\_xDelta,60\*\_yDelta,60\*\_xDelta,60\*\_yDelta);  
\_rectPoint.insert(0, rect1);  
\_rectPoint.insert(1 ,rect2);  
\_rectPointSelected.insert(0, false);  
\_rectPointSelected.insert(1, false);  

}

mygriditem::~mygriditem(){

}

void mygriditem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget){
Q_UNUSED(option);
Q_UNUSED(widget);
painter->setRenderHint(QPainter::Antialiasing, true);
painter->save();
_svgRender->render(painter, _boundRect); // 绘制svg图片
// QGraphicsSvgItem::paint(painter, option, widget);
for(QMap::iterator it = _rectPointSelected.begin(); it != _rectPointSelected.end() ;++it){
if(it.value()){
painter->setPen(Qt::red);
it.value() = false;
}else {
painter->setPen(Qt::green);
}
painter->setBrush(Qt::green);
painter->drawRect(_rectPoint[it.key()]);
}
painter->restore();
}

QRectF mygriditem::boundingRect() const{
return _boundRect;
}

void mygriditem::mousePressEvent(QGraphicsSceneMouseEvent *event){
if(event->button() == Qt::LeftButton){
for(QMap::iterator it = _rectPoint.begin(); it != _rectPoint.end(); ++ it){
if(it.value().contains(event->pos())){
prepareGeometryChange();
_rectPointSelected[it.key()] = true;
update();
// emit syn(it.key());
}
}
}
}
void mygriditem::onSyn(int id){
prepareGeometryChange();
_rectPointSelected[id] = true;
update();
}

-继承QGraphicsView 实现缩放 拖拽（这部分参考其它博主）

mygraphicsview.h

#ifndef MYGRAPHICSVIEW_H
#define MYGRAPHICSVIEW_H

#include
#include

class mygraphicsview:public QGraphicsView
{
public:
explicit mygraphicsview(QWidget *parent = nullptr);
~mygraphicsview();

  // 平移速度  
void setTranslateSpeed(qreal speed);  
qreal translateSpeed() const;

// 缩放的增量  
void setZoomDelta(qreal delta);  
qreal zoomDelta() const;  

protected:
// 上/下/左/右键向各个方向移动、加/减键进行缩放、空格/回车键旋转
void keyPressEvent(QKeyEvent *event) Q_DECL_OVERRIDE;
// 平移
void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
// 放大/缩小
void wheelEvent(QWheelEvent *event) Q_DECL_OVERRIDE;

public Q_SLOTS:
void zoomIn(); // 放大
void zoomOut(); // 缩小
void zoom(float scaleFactor); // 缩放 - scaleFactor缩放的比例因子
void translate(QPointF delta); // 平移

private:
Qt::MouseButton m_translateButton; // 平移按钮
qreal m_translateSpeed; // 平移速度
qreal m_zoomDelta; // 缩放的增量
bool m_bMouseTranslate; // 平移标识
QPoint m_lastMousePos; // 鼠标最后按下的位置
qreal m_scale; // 缩放值
};

#endif // MYGRAPHICSVIEW_H

#include "mygraphicsview.h"

#define VIEW_CENTER viewport()->rect().center()
#define VIEW_WIDTH viewport()->rect().width()
#define VIEW_HEIGHT viewport()->rect().height()

mygraphicsview::mygraphicsview(QWidget *parent):QGraphicsView(parent),
m_translateButton(Qt::LeftButton),
m_scale(1.0),
m_zoomDelta(0.1),
m_translateSpeed(1.0),
m_bMouseTranslate(false)
{
setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setCursor(Qt::PointingHandCursor);
setRenderHint(QPainter::Antialiasing);

// setSceneRect(INT_MIN/2, INT_MIN/2, INT_MAX, INT_MAX);
// setSceneRect(0,0,5472, 3648);
// centerOn(0, 0);

}

mygraphicsview::~mygraphicsview(){

}

// 平移速度
void mygraphicsview::setTranslateSpeed(qreal speed)
{
// 建议速度范围
Q_ASSERT_X(speed >= 0.0 && speed <= 2.0,
"InteractiveView::setTranslateSpeed", "Speed should be in range [0.0, 2.0].");
m_translateSpeed = speed;
}

qreal mygraphicsview::translateSpeed() const
{
return m_translateSpeed;
}

// 缩放的增量
void mygraphicsview::setZoomDelta(qreal delta)
{
// 建议增量范围
Q_ASSERT_X(delta >= 0.0 && delta <= 1.0,
"InteractiveView::setZoomDelta", "Delta should be in range [0.0, 1.0].");
m_zoomDelta = delta;
}

qreal mygraphicsview::zoomDelta() const
{
return m_zoomDelta;
}

// 上/下/左/右键向各个方向移动、加/减键进行缩放、空格/回车键旋转
void mygraphicsview::keyPressEvent(QKeyEvent *event)
{
switch (event->key()) {
case Qt::Key_Up:
translate(QPointF(0, -2)); // 上移
break;
case Qt::Key_Down:
translate(QPointF(0, 2)); // 下移
break;
case Qt::Key_Left:
translate(QPointF(-2, 0)); // 左移
break;
case Qt::Key_Right:
translate(QPointF(2, 0)); // 右移
break;
case Qt::Key_Plus: // 放大
zoomIn();
break;
case Qt::Key_Minus: // 缩小
zoomOut();
break;
case Qt::Key_Space: // 逆时针旋转
rotate(-5);
break;
case Qt::Key_Enter: // 顺时针旋转
case Qt::Key_Return:
rotate(5);
break;
default:
QGraphicsView::keyPressEvent(event);
}
}

// 平移
void mygraphicsview::mouseMoveEvent(QMouseEvent *event)
{
if (m_bMouseTranslate){
QPointF mouseDelta = mapToScene(event->pos()) - mapToScene(m_lastMousePos);
translate(mouseDelta);
}

m\_lastMousePos = event->pos();

QGraphicsView::mouseMoveEvent(event);  

}

void mygraphicsview::mousePressEvent(QMouseEvent *event)
{
if (event->button() == m_translateButton) {
// 当光标底下没有 item 时才能移动
QPointF point = mapToScene(event->pos());
if (scene()->itemAt(point, transform()) != NULL) {
m_bMouseTranslate = true;
m_lastMousePos = event->pos();
}
}

QGraphicsView::mousePressEvent(event);  

}

void mygraphicsview::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == m_translateButton)
m_bMouseTranslate = false;

QGraphicsView::mouseReleaseEvent(event);  

}

// 放大/缩小
void mygraphicsview::wheelEvent(QWheelEvent *event)
{
// 滚轮的滚动量
QPoint scrollAmount = event->angleDelta();
// 正值表示滚轮远离使用者放大负值表示朝向使用者缩小
scrollAmount.y() > 0 ? zoomIn() : zoomOut();
}

// 放大
void mygraphicsview::zoomIn()
{
zoom(1 + m_zoomDelta);
}

// 缩小
void mygraphicsview::zoomOut()
{
zoom(1 - m_zoomDelta);
}

// 缩放 - scaleFactor缩放的比例因子
void mygraphicsview::zoom(float scaleFactor)
{
// 防止过小或过大
qreal factor = transform().scale(scaleFactor, scaleFactor).mapRect(QRectF(0, 0, 1, 1)).width();
if (factor < 0.5 || factor > 100)
return;

scale(scaleFactor, scaleFactor);  
m\_scale \*= scaleFactor;  

}

// 平移
void mygraphicsview::translate(QPointF delta)
{
// 根据当前 zoom 缩放平移数
delta *= m_scale;
delta *= m_translateSpeed;

// view 根据鼠标下的点作为锚点来定位 scene  
setTransformationAnchor(QGraphicsView::AnchorUnderMouse);  
QPoint newCenter(VIEW\_WIDTH / 2 - delta.x(),  VIEW\_HEIGHT / 2 - delta.y());  
centerOn(mapToScene(newCenter));

// scene 在 view 的中心点作为锚点  
setTransformationAnchor(QGraphicsView::AnchorViewCenter);  

}

-测试代码

cview.h

#ifndef CVIEW_H
#define CVIEW_H

#include
#include
#include
#include
#include
#include
#include "mygraphicsview.h"
#include "myimageitem.h"
#include "mygriditem.h"

QT_BEGIN_NAMESPACE
namespace Ui { class CView; }
QT_END_NAMESPACE

class CView : public QWidget
{
Q_OBJECT

public:
CView(QWidget *parent = nullptr);
~CView();

private:
Ui::CView *ui;
QGraphicsScene *_scene;
QGraphicsObject *_codeImgae;
};
#endif // CVIEW_H

#include "cview.h"
#include "./ui_cview.h"

CView::CView(QWidget *parent)
: QWidget(parent),
ui(new Ui::CView),
_scene(new QGraphicsScene)

{
ui->setupUi(this);
QPixmap pixmap;
pixmap.load("XXX.png"); // 传入自己的图片
float pixWidth = pixmap.width();
float pixHeight = pixmap.height();
float deltaX = ui->graphicsView_2->width()/pixWidth;
float deltaY = ui->graphicsView_2->height()/pixHeight;

int viewW = ui->graphicsView\_2->width();  
int viewH = ui->graphicsView\_2->height();

\_codeImgae = new myimageitem(QRectF(0, 0,viewH, viewH),pixmap);  
\_scene->addItem(\_codeImgae);  
ui->graphicsView\_2->setScene(\_scene);  
float w = ui->graphicsView->width();  
float h = ui->graphicsView->height();  
 mygriditem \*svg\_render = new mygriditem(QRectF(0,0,w,h),QString("XXX.svg"));// 传入自己的图片  
QGraphicsScene \*svgScene = new QGraphicsScene();

svgScene->addItem(svg\_render);

QList<QGraphicsItem\*> items = svgScene->items();  
ui->graphicsView->setScene(svgScene);  

}

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