lightmaps.cpp Example File

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 #include <QtCore>
 #include <QtWidgets>
 #include <QtNetwork>

 #include <math.h>

 #include "lightmaps.h"
 #include "slippymap.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

 LightMaps::LightMaps(QWidget *parent)
     : 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 LightMaps::setCenter(qreal lat, qreal lng)
 {
     m_normalMap->latitude = lat;
     m_normalMap->longitude = lng;
     m_normalMap->invalidate();
     m_largeMap->latitude = lat;
     m_largeMap->longitude = lng;
     m_largeMap->invalidate();
 }

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

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

 void LightMaps::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 LightMaps::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 LightMaps::paintEvent(QPaintEvent *event)
 {
     QPainter p;
     p.begin(this);
     m_normalMap->render(&p, event->rect());
     p.setPen(Qt::black);
     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 LightMaps::timerEvent(QTimerEvent *)
 {
     if (!zoomed)
         activateZoom();
     update();
 }

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

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

 void LightMaps::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();
         }
     }
 }