前文链接：QGraphicsView实现简易地图15『测量面积』
一种简单的爆炸波扩散效果
动态演示效果：

静态展示图片：

核心代码：

#pragma once
#include "../AbstractGeoItem.h"
#include "DataStruct/GeoData.h"/** 爆炸扩散效果-静态*/class ExplosiveDiffusionItem : public AbstractGeoItem
{
public:ExplosiveDiffusionItem(const GeoCoord &geoCoord, int radius, QGraphicsItem *parent = nullptr);~ExplosiveDiffusionItem();// 更新地理位置virtual void updateGeoPos();protected:virtual QRectF boundingRect() const override;virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;// 设置半径（单位：米）void setRadius(int radius);// 获取半径（单位：米）int radius();protected:int m_radius;	// 半径（单位：米）double m_rw;	// 基于指定经纬度处的椭圆横轴半径double m_rh;	// 基于指定经纬度处的椭圆竖轴半径
};

#include "ExplosiveDiffusionItem.h"
#include <QRadialGradient>
#include <QPainter>
#include "Utility/MapUtility.h"ExplosiveDiffusionItem::ExplosiveDiffusionItem(const GeoCoord &geoCoord, int radius, QGraphicsItem *parent /*= nullptr*/) : AbstractGeoItem(parent)
{setZValue(300);setGeoPos(geoCoord.lon, geoCoord.lat);m_radius = radius;
}ExplosiveDiffusionItem::~ExplosiveDiffusionItem()
{}void ExplosiveDiffusionItem::updateGeoPos()
{AbstractGeoItem::updateGeoPos();prepareGeometryChange();
}QRectF ExplosiveDiffusionItem::boundingRect() const
{return QRectF(-m_rw, -m_rh, 2 * m_rw, 2 * m_rh);
}void ExplosiveDiffusionItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{QRadialGradient gr(0, 0, m_rw, 0, 0);gr.setColorAt(0.0, QColor(255, 255, 255, 0));gr.setColorAt(0.90, QColor(255, 255, 255, 10));gr.setColorAt(0.94, QColor(255, 255, 255, 40));gr.setColorAt(0.99, QColor(185, 225, 240, 255));gr.setColorAt(1, QColor(185, 225, 240, 128));painter->setRenderHint(QPainter::Antialiasing);painter->setBrush(gr);painter->setPen(Qt::NoPen);painter->drawEllipse(boundingRect());
}void ExplosiveDiffusionItem::setRadius(int radius)
{m_radius = radius;GeoCoord right = MapUtility::geoCoordByDisAndBearing(m_lon, m_lat, 90, m_radius);GeoCoord top = MapUtility::geoCoordByDisAndBearing(m_lon, m_lat, 0, m_radius);QPointF rightPos = sceneCoordFromGeoCoord(right.lon, right.lat);QPointF topPos = sceneCoordFromGeoCoord(top.lon, top.lat);QPointF centerPos = sceneCoordFromGeoCoord(m_lon, m_lat);m_rw = rightPos.x() - centerPos.x();m_rh = centerPos.y() - topPos.y();prepareGeometryChange();
}int ExplosiveDiffusionItem::radius()
{return m_radius;
}

此处提供的动态效果，是利用QPropertyAnimation制作而成，后面文章的动态效果也是采用这种方法，后续将不再展示代码，参考此处即可。

#pragma once
#include "ExplosiveDiffusionItem.h"/** 爆炸扩散效果-动态扩散*/class QPropertyAnimation;class ExplosiveDiffusionAnimateItem : public QObject, public ExplosiveDiffusionItem
{Q_OBJECTQ_PROPERTY(int m_radius WRITE setRadius READ radius)public:ExplosiveDiffusionAnimateItem(const GeoCoord &geoCoord, int radius, QGraphicsItem *parent = nullptr);~ExplosiveDiffusionAnimateItem();void start(int msecs = 1000);private:QPropertyAnimation *m_animation;
};

#include "ExplosiveDiffusionAnimateItem.h"
#include <QPropertyAnimation>ExplosiveDiffusionAnimateItem::ExplosiveDiffusionAnimateItem(const GeoCoord &geoCoord, int radius, QGraphicsItem *parent /*= nullptr*/): ExplosiveDiffusionItem(geoCoord, radius, parent)
{m_animation = new QPropertyAnimation(this, "m_radius", this);m_animation->setEasingCurve(QEasingCurve::InOutQuad);connect(m_animation, &QAbstractAnimation::finished, this, &ExplosiveDiffusionAnimateItem::finished);
}ExplosiveDiffusionAnimateItem::~ExplosiveDiffusionAnimateItem()
{}void ExplosiveDiffusionAnimateItem::start(int msecs/* = 1000*/)
{if (m_animation->state() != QAbstractAnimation::Stopped)m_animation->stop();m_animation->setDuration(msecs);m_animation->setStartValue(0);m_animation->setEndValue(m_radius);m_animation->start();
}