QgraphicsView异步线程加载地图瓦片

本节主要记录一下qt开发过程中离线地图瓦片的加载方式瓦片加载选择graphicsView控件同时为了不影响主线程事件和其他操作这里采用了异步线程的操作将地图瓦片加载的步骤放到了异步子线程之中。注本记录仅为本人笔记记录。一、效果展示二、代码展示1、思路设计中我们先选择graphicsView放置与ui设计界面以作为瓦片的存放容器。创建子线程线程功能实现为筛选对应坐标编号的地图瓦片信息并传递给主线程进行显示主线程开启子线程的运行并获取子线程传递的对应瓦片地图信息进行显示。2、子线程代码实现#ifndef MAPWORK_H #define MAPWORK_H #include QObject #include QPixmap #include QFile class mapWork : public QObject { Q_OBJECT public: explicit mapWork(int zoom, int tileSize, QObject *parent nullptr) : QObject(parent), m_zoom(zoom), m_tileSize(tileSize) {} public slots: //自定义函数是实现瓦片的查找和加载 void loadTiles(int xStart, int xEnd, int yStart, int yEnd, const QString basePath) { //X层级和y层级代表地图瓦片编号相对应的层级 for(int x xStart; x xEnd; x) { for(int y yStart; y yEnd; y) { //我的瓦片图文件存放在程序目录下的mapabc目录satellite目录对应的是卫星地图瓦片overlay目录对应的是街道瓦片数据 //先加载卫星瓦片地图 QString filename_1 QString(%1/mapabc/satellite/%2/%3/%4.jpg) .arg(basePath) .arg(m_zoom) .arg(x) .arg(y); if(QFile::exists(filename_1)) { QPixmap pixmap(filename_1); if(!pixmap.isNull()) { emit tileLoaded(x, y, pixmap);//发送瓦片数据信息 对应的层级和图片文件 } //加载街道地图瓦片 QString filename_2 QString(%1/mapabc/overlay/%2/%3/%4.png) .arg(basePath) .arg(m_zoom) .arg(x) .arg(y); if(QFile::exists(filename_2)) { QPixmap pixmap2(filename_2); if(!pixmap.isNull()) { emit tileLoaded(x, y, pixmap2);//发送瓦片数据信息 对应的层级和图片文件 } } } } emit finished(); } } signals: void tileLoaded(int x, int y, const QPixmap pixmap); //定义信号传递主线程对应的瓦片信息 void finished(); private: int m_zoom; //瓦片层级 int m_tileSize; //瓦片的大小 256*256此处为256 }; #endif // MAPWORK_H3、主函数代码功能实现mainwindow.h文件#ifndef MAINWINDOW_H #define MAINWINDOW_H #include QMainWindow #include QGraphicsScene //场景 #include QGraphicsView //视图 #include QGraphicsItem //图元 #include QDir #include mapwork.h #include QThread QT_BEGIN_NAMESPACE namespace Ui { class MainWindow; } QT_END_NAMESPACE class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent nullptr); ~MainWindow(); private: void setMap(); private slots: void addTileToScene(int x, int y, const QPixmap pixmap); private: void setupThread(); Ui::MainWindow *ui; QGraphicsScene *myScene; //map 线程加载 mapWork *m_worker; QThread *m_workerThread; //map相关 int zoom 14;//地图层级 int wap_X_start 13373; //x层级瓦片和y层级瓦片的开始结束标号 int wap_X_end 13604; int wap_Y_start 6123; int wap_Y_end 6290; //程序路径 QDir currentDir QDir::current(); int tileSize 256;//每个瓦片的像素边长 256*256 }; #endif // MAINWINDOW_Hmainwindow.cpp文件#include mainwindow.h #include ui_mainwindow.h #include QPixmap #include QTimer MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow), zoom(14), currentDir(QDir::current()), tileSize(256) { ui-setupUi(this); setupThread();//进入线程加载图片 //场景设置 myScene new QGraphicsScene(this); //初始化视图 ui-graphicsView-setScene(myScene); ui-graphicsView-setRenderHint(QPainter::SmoothPixmapTransform); ui-graphicsView-setCacheMode(QGraphicsView::CacheBackground); setMap(); } MainWindow::~MainWindow() { delete ui; if(m_workerThread m_workerThread-isRunning()) { qDebug() Stopping worker thread...; m_workerThread-quit(); if(!m_workerThread-wait(3000)) { qCritical() 线程未正常退出强制终止; m_workerThread-terminate(); } } } void MainWindow::setupThread() { m_workerThread new QThread(this); m_worker new mapWork(zoom, tileSize); m_worker-moveToThread(m_workerThread); // 完整信号连接 connect(m_worker, mapWork::tileLoaded, this, MainWindow::addTileToScene); connect(m_workerThread, QThread::finished, m_worker, QObject::deleteLater); m_workerThread-start(); } void MainWindow::setMap() { const QString basePath currentDir.absolutePath(); //线程安全 QMetaObject::invokeMethod(m_worker, loadTiles, Qt::QueuedConnection, Q_ARG(int, wap_X_start), Q_ARG(int, wap_X_end), Q_ARG(int, wap_Y_start), Q_ARG(int, wap_Y_end), Q_ARG(QString, basePath)); } //插入图片元素 void MainWindow::addTileToScene(int x, int y, const QPixmap pixmap) { QGraphicsPixmapItem* item myScene-addPixmap(pixmap); item-setPos(x * tileSize, y * tileSize); }