Question

我试图制作一个QGraphicObject，它代表一个带圆角的矩形，可以用鼠标移动。

项目似乎绘制正确，在搜索文档后，我发现我必须设置标志QGraphicsItem::ItemIsMovable，使项目向右移动，但它总是比鼠标移动得快，所以我做错了什么？

这是.h文件：

class GraphicRoundedRectObject : public GraphicObject
{
    Q_OBJECT
public:
    explicit GraphicRoundedRectObject(
            qreal x ,
            qreal y ,
            qreal width ,
            qreal height ,
            qreal radius=0,
            QGraphicsItem *parent = nullptr);
    virtual ~GraphicRoundedRectObject();


    qreal radius() const;
    void setRadius(qreal radius);
    qreal height() const ;
    void setHeight(qreal height) ;
    qreal width() const ;
    void setWidth(qreal width) ;

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *) override;
    QRectF boundingRect() const override;

private:
    qreal m_radius;
    qreal m_width;
    qreal m_height;
};

和.cpp：

#include "graphicroundedrectobject.h"
#include <QPainter>

GraphicRoundedRectObject::GraphicRoundedRectObject(
        qreal x ,
        qreal y ,
        qreal width ,
        qreal height ,
        qreal radius,
        QGraphicsItem *parent
        )
    : GraphicObject(parent)
    , m_radius(radius)
    , m_width(width)
    , m_height(height)
{
    setX(x);
    setY(y);
    setFlag(QGraphicsItem::ItemIsMovable);
}

GraphicRoundedRectObject::~GraphicRoundedRectObject() {
}

void GraphicRoundedRectObject::paint
(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget*) {
    painter->drawRoundedRect(x(), y(),m_width, m_height, m_radius, m_radius );
}

QRectF GraphicRoundedRectObject::boundingRect() const {
    return QRectF(x(), y(), m_width, m_height);
}

Answer 1

这是因为您在父坐标中绘制矩形而不是对象的坐标。

应该是：

void GraphicRoundedRectObject::paint(QPainter *painter,
                                     const QStyleOptionGraphicsItem *, QWidget*) {
    painter->drawRoundedRect(0.0, 0.0,m_width, m_height, m_radius, m_radius );
}

QRectF GraphicRoundedRectObject::boundingRect() const {
    return QRectF(0.0, 0.0, m_width, m_height);
}

实现可移动的QGraphicsObject子类

1 个答案: