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# lightmaps.cpp Example File
demos/embedded/lightmaps/lightmaps.cpp

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     #include <QtCore>
     #include <QtGui>
     #include <QtNetwork>

     #if defined (Q_OS_SYMBIAN)
     #include "sym_iap_util.h"
     #endif

     #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;

     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

             QTimer::singleShot(0, this, SLOT(delayedInit()));
         }

     private slots:

         void delayedInit() {
     #if defined(Q_OS_SYMBIAN)
             qt_SetDefaultIap();
     #endif
         }

         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();
     }