Qt工作笔记-第三种方法在QGraphics上写文本

前面的两种方法：

QGraphicsSimpleTextIte和QGraphicsTextItem

如下：

https://blog.csdn.net/qq78442761/article/details/81740672

下面说的是继承法，重写

painter，然后drawText

运行截图如下：

源码如下：

mygraphicsitem.h

#ifndef MYGRAPHICSITEM_H
#define MYGRAPHICSITEM_H

#include <QGraphicsItem>

class MyGraphicsItem : public QGraphicsItem
{
public:
    explicit MyGraphicsItem();
    QRectF boundingRect()const Q_DECL_OVERRIDE;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) Q_DECL_OVERRIDE;

    qreal graphicsWidth;
    qreal graphicsHeight;
};

#endif // MYGRAPHICSITEM_H

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

QT_BEGIN_NAMESPACE
class QGraphicsScene;
QT_END_NAMESPACE

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

private:
    Ui::Widget *ui;

    QGraphicsScene *m_scene;
};

#endif // WIDGET_H

main.cpp

#include "widget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

mygraphicsitem.cpp

#include "mygraphicsitem.h"
#include <QPainter>
#include <QPen>
#include <QFont>

MyGraphicsItem::MyGraphicsItem()
{

}

QRectF MyGraphicsItem::boundingRect() const
{
    qreal penWidth=1;
    return QRectF(0-penWidth/2,0-penWidth/2,graphicsWidth+penWidth,graphicsHeight+penWidth);
}

void MyGraphicsItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    Q_UNUSED(option)
    Q_UNUSED(widget)
    painter->setFont(QFont("华文琥珀",12));
    painter->setPen(QPen(Qt::white));
    painter->drawText(20,20,"painter drawText English  中文");
}

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include "mygraphicsitem.h"
#include <QGraphicsScene>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);

    m_scene=new QGraphicsScene;
    ui->graphicsView->setBackgroundBrush(QBrush(Qt::black));
    ui->graphicsView->setScene(m_scene);

    MyGraphicsItem *item=new MyGraphicsItem;
    item->graphicsHeight=50;
    item->graphicsWidth=300;
    m_scene->addItem(item);

    item->setFlags(QGraphicsItem::ItemIsMovable|QGraphicsItem::ItemIsSelectable);
}

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