Qt Reference Documentation

lightmaps.cpp Example File

demos/embedded/lightmaps/lightmaps.cpp
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 #include <QtCore>
 #include <QtGui>
 #include <QtNetwork>

 #include <math.h>

 #ifndef M_PI
 #define M_PI 3.14159265358979323846
 #endif

 // how long (milliseconds) the user need to hold (after a tap on the screen)
 // before triggering the magnifying glass feature
 // 701, a prime number, is the sum of 229, 233, 239
 // (all three are also prime numbers, consecutive!)
 #define HOLD_TIME 701

 // maximum size of the magnifier
 // Hint: see above to find why I picked this one :)
 #define MAX_MAGNIFIER 229

 uint qHash(const QPoint& p)
 {
     return p.x() * 17 ^ p.y();
 }

 // tile size in pixels
 const int tdim = 256;

 QPointF tileForCoordinate(qreal lat, qreal lng, int zoom)
 {
     qreal zn = static_cast<qreal>(1 << zoom);
     qreal tx = (lng + 180.0) / 360.0;
     qreal ty = (1.0 - log(tan(lat * M_PI / 180.0) +
                           1.0 / cos(lat * M_PI / 180.0)) / M_PI) / 2.0;
     return QPointF(tx * zn, ty * zn);
 }

 qreal longitudeFromTile(qreal tx, int zoom)
 {
     qreal zn = static_cast<qreal>(1 << zoom);
     qreal lat = tx / zn * 360.0 - 180.0;
     return lat;
 }

 qreal latitudeFromTile(qreal ty, int zoom)
 {
     qreal zn = static_cast<qreal>(1 << zoom);
     qreal n = M_PI - 2 * M_PI * ty / zn;
     qreal lng = 180.0 / M_PI * atan(0.5 * (exp(n) - exp(-n)));
     return lng;
 }

 class SlippyMap: public QObject
 {
     Q_OBJECT

 public:
     int width;
     int height;
     int zoom;
     qreal latitude;
     qreal longitude;

     SlippyMap(QObject *parent = 0)
             : QObject(parent)
             , width(400)
             , height(300)
             , zoom(15)
             , latitude(59.9138204)
             , longitude(10.7387413) {
         m_emptyTile = QPixmap(tdim, tdim);
         m_emptyTile.fill(Qt::lightGray);

         QNetworkDiskCache *cache = new QNetworkDiskCache;
         cache->setCacheDirectory(QDesktopServices::storageLocation
                                  (QDesktopServices::CacheLocation));
         m_manager.setCache(cache);
         connect(&m_manager, SIGNAL(finished(QNetworkReply*)),
                 this, SLOT(handleNetworkData(QNetworkReply*)));
     }

     void invalidate() {
         if (width <= 0 || height <= 0)
             return;

         QPointF ct = tileForCoordinate(latitude, longitude, zoom);
         qreal tx = ct.x();
         qreal ty = ct.y();

         // top-left corner of the center tile
         int xp = width / 2 - (tx - floor(tx)) * tdim;
         int yp = height / 2 - (ty - floor(ty)) * tdim;

         // first tile vertical and horizontal
         int xa = (xp + tdim - 1) / tdim;
         int ya = (yp + tdim - 1) / tdim;
         int xs = static_cast<int>(tx) - xa;
         int ys = static_cast<int>(ty) - ya;

         // offset for top-left tile
         m_offset = QPoint(xp - xa * tdim, yp - ya * tdim);

         // last tile vertical and horizontal
         int xe = static_cast<int>(tx) + (width - xp - 1) / tdim;
         int ye = static_cast<int>(ty) + (height - yp - 1) / tdim;

         // build a rect
         m_tilesRect = QRect(xs, ys, xe - xs + 1, ye - ys + 1);

         if (m_url.isEmpty())
             download();

         emit updated(QRect(0, 0, width, height));
     }

     void render(QPainter *p, const QRect &rect) {
         for (int x = 0; x <= m_tilesRect.width(); ++x)
             for (int y = 0; y <= m_tilesRect.height(); ++y) {
                 QPoint tp(x + m_tilesRect.left(), y + m_tilesRect.top());
                 QRect box = tileRect(tp);
                 if (rect.intersects(box)) {
                     if (m_tilePixmaps.contains(tp))
                         p->drawPixmap(box, m_tilePixmaps.value(tp));
                     else
                         p->drawPixmap(box, m_emptyTile);
                 }
             }
     }

     void pan(const QPoint &delta) {
         QPointF dx = QPointF(delta) / qreal(tdim);
         QPointF center = tileForCoordinate(latitude, longitude, zoom) - dx;
         latitude = latitudeFromTile(center.y(), zoom);
         longitude = longitudeFromTile(center.x(), zoom);
         invalidate();
     }

 private slots:

     void handleNetworkData(QNetworkReply *reply) {
         QImage img;
         QPoint tp = reply->request().attribute(QNetworkRequest::User).toPoint();
         QUrl url = reply->url();
         if (!reply->error())
             if (!img.load(reply, 0))
                 img = QImage();
         reply->deleteLater();
         m_tilePixmaps[tp] = QPixmap::fromImage(img);
         if (img.isNull())
             m_tilePixmaps[tp] = m_emptyTile;
         emit updated(tileRect(tp));

         // purge unused spaces
         QRect bound = m_tilesRect.adjusted(-2, -2, 2, 2);
         foreach(QPoint tp, m_tilePixmaps.keys())
         if (!bound.contains(tp))
             m_tilePixmaps.remove(tp);

         download();
     }

     void download() {
         QPoint grab(0, 0);
         for (int x = 0; x <= m_tilesRect.width(); ++x)
             for (int y = 0; y <= m_tilesRect.height(); ++y) {
                 QPoint tp = m_tilesRect.topLeft() + QPoint(x, y);
                 if (!m_tilePixmaps.contains(tp)) {
                     grab = tp;
                     break;
                 }
             }
         if (grab == QPoint(0, 0)) {
             m_url = QUrl();
             return;
         }

         QString path = "http://tile.openstreetmap.org/%1/%2/%3.png";
         m_url = QUrl(path.arg(zoom).arg(grab.x()).arg(grab.y()));
         QNetworkRequest request;
         request.setUrl(m_url);
         request.setRawHeader("User-Agent", "Nokia (Qt) Graphics Dojo 1.0");
         request.setAttribute(QNetworkRequest::User, QVariant(grab));
         m_manager.get(request);
     }

 signals:
     void updated(const QRect &rect);

 protected:
     QRect tileRect(const QPoint &tp) {
         QPoint t = tp - m_tilesRect.topLeft();
         int x = t.x() * tdim + m_offset.x();
         int y = t.y() * tdim + m_offset.y();
         return QRect(x, y, tdim, tdim);
     }

 private:
     QPoint m_offset;
     QRect m_tilesRect;
     QPixmap m_emptyTile;
     QHash<QPoint, QPixmap> m_tilePixmaps;
     QNetworkAccessManager m_manager;
     QUrl m_url;
 };

 class LightMaps: public QWidget
 {
     Q_OBJECT

 public:
     LightMaps(QWidget *parent = 0)
             : QWidget(parent)
             , pressed(false)
             , snapped(false)
             , zoomed(false)
             , invert(false) {
         m_normalMap = new SlippyMap(this);
         m_largeMap = new SlippyMap(this);
         connect(m_normalMap, SIGNAL(updated(QRect)), SLOT(updateMap(QRect)));
         connect(m_largeMap, SIGNAL(updated(QRect)), SLOT(update()));
     }

     void setCenter(qreal lat, qreal lng) {
         m_normalMap->latitude = lat;
         m_normalMap->longitude = lng;
         m_normalMap->invalidate();
         m_largeMap->invalidate();
     }

 public slots:
     void toggleNightMode() {
         invert = !invert;
         update();
     }

 private slots:
     void updateMap(const QRect &r) {
         update(r);
     }

 protected:

     void activateZoom() {
         zoomed = true;
         tapTimer.stop();
         m_largeMap->zoom = m_normalMap->zoom + 1;
         m_largeMap->width = m_normalMap->width * 2;
         m_largeMap->height = m_normalMap->height * 2;
         m_largeMap->latitude = m_normalMap->latitude;
         m_largeMap->longitude = m_normalMap->longitude;
         m_largeMap->invalidate();
         update();
     }

     void resizeEvent(QResizeEvent *) {
         m_normalMap->width = width();
         m_normalMap->height = height();
         m_normalMap->invalidate();
         m_largeMap->width = m_normalMap->width * 2;
         m_largeMap->height = m_normalMap->height * 2;
         m_largeMap->invalidate();
     }

     void paintEvent(QPaintEvent *event) {
         QPainter p;
         p.begin(this);
         m_normalMap->render(&p, event->rect());
         p.setPen(Qt::black);
 #if defined(Q_OS_SYMBIAN)
         QFont font = p.font();
         font.setPixelSize(13);
         p.setFont(font);
 #endif
         p.drawText(rect(),  Qt::AlignBottom | Qt::TextWordWrap,
                    "Map data CCBYSA 2009 OpenStreetMap.org contributors");
         p.end();

         if (zoomed) {
             int dim = qMin(width(), height());
             int magnifierSize = qMin(MAX_MAGNIFIER, dim * 2 / 3);
             int radius = magnifierSize / 2;
             int ring = radius - 15;
             QSize box = QSize(magnifierSize, magnifierSize);

             // reupdate our mask
             if (maskPixmap.size() != box) {
                 maskPixmap = QPixmap(box);
                 maskPixmap.fill(Qt::transparent);

                 QRadialGradient g;
                 g.setCenter(radius, radius);
                 g.setFocalPoint(radius, radius);
                 g.setRadius(radius);
                 g.setColorAt(1.0, QColor(255, 255, 255, 0));
                 g.setColorAt(0.5, QColor(128, 128, 128, 255));

                 QPainter mask(&maskPixmap);
                 mask.setRenderHint(QPainter::Antialiasing);
                 mask.setCompositionMode(QPainter::CompositionMode_Source);
                 mask.setBrush(g);
                 mask.setPen(Qt::NoPen);
                 mask.drawRect(maskPixmap.rect());
                 mask.setBrush(QColor(Qt::transparent));
                 mask.drawEllipse(g.center(), ring, ring);
                 mask.end();
             }

             QPoint center = dragPos - QPoint(0, radius);
             center = center + QPoint(0, radius / 2);
             QPoint corner = center - QPoint(radius, radius);

             QPoint xy = center * 2 - QPoint(radius, radius);

             // only set the dimension to the magnified portion
             if (zoomPixmap.size() != box) {
                 zoomPixmap = QPixmap(box);
                 zoomPixmap.fill(Qt::lightGray);
             }
             if (true) {
                 QPainter p(&zoomPixmap);
                 p.translate(-xy);
                 m_largeMap->render(&p, QRect(xy, box));
                 p.end();
             }

             QPainterPath clipPath;
             clipPath.addEllipse(center, ring, ring);

             QPainter p(this);
             p.setRenderHint(QPainter::Antialiasing);
             p.setClipPath(clipPath);
             p.drawPixmap(corner, zoomPixmap);
             p.setClipping(false);
             p.drawPixmap(corner, maskPixmap);
             p.setPen(Qt::gray);
             p.drawPath(clipPath);
         }
         if (invert) {
             QPainter p(this);
             p.setCompositionMode(QPainter::CompositionMode_Difference);
             p.fillRect(event->rect(), Qt::white);
             p.end();
         }
     }

     void timerEvent(QTimerEvent *) {
         if (!zoomed)
             activateZoom();
         update();
     }

     void mousePressEvent(QMouseEvent *event) {
         if (event->buttons() != Qt::LeftButton)
             return;
         pressed = snapped = true;
         pressPos = dragPos = event->pos();
         tapTimer.stop();
         tapTimer.start(HOLD_TIME, this);
     }

     void mouseMoveEvent(QMouseEvent *event) {
         if (!event->buttons())
             return;
         if (!zoomed) {
             if (!pressed || !snapped) {
                 QPoint delta = event->pos() - pressPos;
                 pressPos = event->pos();
                 m_normalMap->pan(delta);
                 return;
             } else {
                 const int threshold = 10;
                 QPoint delta = event->pos() - pressPos;
                 if (snapped) {
                     snapped &= delta.x() < threshold;
                     snapped &= delta.y() < threshold;
                     snapped &= delta.x() > -threshold;
                     snapped &= delta.y() > -threshold;
                 }
                 if (!snapped)
                     tapTimer.stop();
             }
         } else {
             dragPos = event->pos();
             update();
         }
     }

     void mouseReleaseEvent(QMouseEvent *) {
         zoomed = false;
         update();
     }

     void keyPressEvent(QKeyEvent *event) {
         if (!zoomed) {
             if (event->key() == Qt::Key_Left)
                 m_normalMap->pan(QPoint(20, 0));
             if (event->key() == Qt::Key_Right)
                 m_normalMap->pan(QPoint(-20, 0));
             if (event->key() == Qt::Key_Up)
                 m_normalMap->pan(QPoint(0, 20));
             if (event->key() == Qt::Key_Down)
                 m_normalMap->pan(QPoint(0, -20));
             if (event->key() == Qt::Key_Z || event->key() == Qt::Key_Select) {
                 dragPos = QPoint(width() / 2, height() / 2);
                 activateZoom();
             }
         } else {
             if (event->key() == Qt::Key_Z || event->key() == Qt::Key_Select) {
                 zoomed = false;
                 update();
             }
             QPoint delta(0, 0);
             if (event->key() == Qt::Key_Left)
                 delta = QPoint(-15, 0);
             if (event->key() == Qt::Key_Right)
                 delta = QPoint(15, 0);
             if (event->key() == Qt::Key_Up)
                 delta = QPoint(0, -15);
             if (event->key() == Qt::Key_Down)
                 delta = QPoint(0, 15);
             if (delta != QPoint(0, 0)) {
                 dragPos += delta;
                 update();
             }
         }
     }

 private:
     SlippyMap *m_normalMap;
     SlippyMap *m_largeMap;
     bool pressed;
     bool snapped;
     QPoint pressPos;
     QPoint dragPos;
     QBasicTimer tapTimer;
     bool zoomed;
     QPixmap zoomPixmap;
     QPixmap maskPixmap;
     bool invert;
 };

 class MapZoom : public QMainWindow
 {
     Q_OBJECT

 private:
     LightMaps *map;
     QNetworkSession *networkSession;

 public:
     MapZoom(): QMainWindow(0) {
         map = new LightMaps(this);
         setCentralWidget(map);
         map->setFocus();

         QAction *osloAction = new QAction("&Oslo", this);
         QAction *berlinAction = new QAction("&Berlin", this);
         QAction *jakartaAction = new QAction("&Jakarta", this);
         QAction *nightModeAction = new QAction("Night Mode", this);
         nightModeAction->setCheckable(true);
         nightModeAction->setChecked(false);
         QAction *osmAction = new QAction("About OpenStreetMap", this);
         connect(osloAction, SIGNAL(triggered()), SLOT(chooseOslo()));
         connect(berlinAction, SIGNAL(triggered()), SLOT(chooseBerlin()));
         connect(jakartaAction, SIGNAL(triggered()), SLOT(chooseJakarta()));
         connect(nightModeAction, SIGNAL(triggered()), map, SLOT(toggleNightMode()));
         connect(osmAction, SIGNAL(triggered()), SLOT(aboutOsm()));

 #if defined(Q_OS_SYMBIAN) || defined(Q_OS_WINCE_WM)
         menuBar()->addAction(osloAction);
         menuBar()->addAction(berlinAction);
         menuBar()->addAction(jakartaAction);
         menuBar()->addAction(nightModeAction);
         menuBar()->addAction(osmAction);
 #else
         QMenu *menu = menuBar()->addMenu("&Options");
         menu->addAction(osloAction);
         menu->addAction(berlinAction);
         menu->addAction(jakartaAction);
         menu->addSeparator();
         menu->addAction(nightModeAction);
         menu->addAction(osmAction);
 #endif

         QNetworkConfigurationManager manager;
         if (manager.capabilities() & QNetworkConfigurationManager::NetworkSessionRequired) {
             // Get saved network configuration
             QSettings settings(QSettings::UserScope, QLatin1String("Trolltech"));
             settings.beginGroup(QLatin1String("QtNetwork"));
             const QString id =
                 settings.value(QLatin1String("DefaultNetworkConfiguration")).toString();
             settings.endGroup();

             // If the saved network configuration is not currently discovered use the system
             // default
             QNetworkConfiguration config = manager.configurationFromIdentifier(id);
             if ((config.state() & QNetworkConfiguration::Discovered) !=
                 QNetworkConfiguration::Discovered) {
                 config = manager.defaultConfiguration();
             }

             networkSession = new QNetworkSession(config, this);
             connect(networkSession, SIGNAL(opened()), this, SLOT(sessionOpened()));

             networkSession->open();
         } else {
             networkSession = 0;
         }
     }

 private slots:

     void sessionOpened() {
         // Save the used configuration
         QNetworkConfiguration config = networkSession->configuration();
         QString id;
         if (config.type() == QNetworkConfiguration::UserChoice) {
             id = networkSession->sessionProperty(
                     QLatin1String("UserChoiceConfiguration")).toString();
         } else {
             id = config.identifier();
         }

         QSettings settings(QSettings::UserScope, QLatin1String("Trolltech"));
         settings.beginGroup(QLatin1String("QtNetwork"));
         settings.setValue(QLatin1String("DefaultNetworkConfiguration"), id);
         settings.endGroup();
     }

     void chooseOslo() {
         map->setCenter(59.9138204, 10.7387413);
     }

     void chooseBerlin() {
         map->setCenter(52.52958999943302, 13.383053541183472);
     }

     void chooseJakarta() {
         map->setCenter(-6.211544, 106.845172);
     }

     void aboutOsm() {
         QDesktopServices::openUrl(QUrl("http://www.openstreetmap.org"));
     }
 };

 #include "lightmaps.moc"

 int main(int argc, char **argv)
 {
 #if defined(Q_WS_X11)
     QApplication::setGraphicsSystem("raster");
 #endif

     QApplication app(argc, argv);
     app.setApplicationName("LightMaps");

     MapZoom w;
     w.setWindowTitle("OpenStreetMap");
 #if defined(Q_OS_SYMBIAN) || defined(Q_OS_WINCE_WM)
     w.showMaximized();
 #else
     w.resize(600, 450);
     w.show();
 #endif

     return app.exec();
 }
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