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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
#include <QtWidgets>
#include <QtNetwork>
#include "slippymap.h"
#include "qmath.h"
// tile size in pixels
const int tdim = 256;
QPointF tileForCoordinate(qreal lat, qreal lng, int zoom)
{
qreal radianLat = qDegreesToRadians(lat);
qreal zn = static_cast<qreal>(1 << zoom);
qreal tx = (lng + 180.0) / 360.0;
qreal ty = 0.5 - log(tan(radianLat) + 1.0 / cos(radianLat)) / 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;
return qRadiansToDegrees(atan(sinh(n)));
}
SlippyMap::SlippyMap(QObject *parent)
: 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(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
m_manager.setCache(cache);
connect(&m_manager, SIGNAL(finished(QNetworkReply*)),
this, SLOT(handleNetworkData(QNetworkReply*)));
}
void SlippyMap::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 SlippyMap::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 SlippyMap::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();
}
void SlippyMap::handleNetworkData(QNetworkReply *reply)
{
QImage img;
QPoint tp = reply->request().attribute(QNetworkRequest::User).toPoint();
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
const QRect bound = m_tilesRect.adjusted(-2, -2, 2, 2);
for (auto it = m_tilePixmaps.keyBegin(); it != m_tilePixmaps.keyEnd(); ++it) {
const QPoint &tp = *it;
if (!bound.contains(tp))
m_tilePixmaps.remove(tp);
}
download();
}
void SlippyMap::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", "The Qt Company (Qt) Graphics Dojo 1.0");
request.setAttribute(QNetworkRequest::User, QVariant(grab));
m_manager.get(request);
}
QRect SlippyMap::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);
}
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