Use asynchronous tiles rendering in IMG maps

On Android devices, the rendering is very slow so use the same approach as
already used in Mapsforge maps.

src/map/IMG/rastertile.cpp

@@ -174,6 +174,8 @@ void RasterTile::render()
 
 	qDeleteAll(textItems);
 
+	_valid = true;
+
 	//painter.setPen(Qt::red);
 	//painter.setRenderHint(QPainter::Antialiasing, false);
 	//painter.drawRect(QRect(_xy, _pixmap.size()));
@@ -185,7 +187,7 @@ void RasterTile::ll2xy(QList<MapData::Poly> &polys)
 		MapData::Poly &poly = polys[i];
 		for (int j = 0; j < poly.points.size(); j++) {
 			QPointF &p = poly.points[j];
-			p = _map->ll2xy(Coordinates(p.x(), p.y()));
+			p = ll2xy(Coordinates(p.x(), p.y()));
 		}
 	}
 }
@@ -193,7 +195,7 @@ void RasterTile::ll2xy(QList<MapData::Poly> &polys)
 void RasterTile::ll2xy(QList<MapData::Point> &points)
 {
 	for (int i = 0; i < points.size(); i++) {
-		QPointF p(_map->ll2xy(points.at(i).coordinates));
+		QPointF p(ll2xy(points.at(i).coordinates));
 		points[i].coordinates = Coordinates(p.x(), p.y());
 	}
 }
@@ -210,8 +212,8 @@ void RasterTile::drawPolygons(QPainter *painter)
 
 			if (poly.raster.isValid()) {
 				RectC r(poly.raster.rect());
-				QPointF tl(_map->ll2xy(r.topLeft()));
-				QPointF br(_map->ll2xy(r.bottomRight()));
+				QPointF tl(ll2xy(r.topLeft()));
+				QPointF br(ll2xy(r.bottomRight()));
 				QSizeF size(QRectF(tl, br).size());
 
 				bool insert = false;

src/map/IMG/rastertile.h

@@ -3,6 +3,8 @@
 
 #include <QPixmap>
 #include "mapdata.h"
+#include "map/projection.h"
+#include "map/transform.h"
 
 class QPainter;
 class IMGMap;
@@ -15,20 +17,25 @@ class Style;
 class RasterTile
 {
 public:
-	RasterTile(IMGMap *map, const Style *style, int zoom, const QRect &rect,
-	  qreal ratio, const QString &key, const QList<MapData::Poly> &polygons,
+	RasterTile(const Projection &proj, const Transform &transform,
+	  const Style *style, int zoom, const QRect &rect, qreal ratio,
+	  const QString &key, const QList<MapData::Poly> &polygons,
 	  const QList<MapData::Poly> &lines, QList<MapData::Point> &points)
-	  : _map(map), _style(style), _zoom(zoom), _rect(rect), _ratio(ratio),
-	  _key(key), _pixmap(rect.width() * ratio, rect.height() * ratio),
-	  _polygons(polygons), _lines(lines), _points(points) {}
+	  : _proj(proj), _transform(transform), _style(style), _zoom(zoom),
+	  _rect(rect), _ratio(ratio), _key(key),
+	  _pixmap(rect.width() * ratio, rect.height() * ratio), _polygons(polygons),
+	  _lines(lines), _points(points), _valid(false) {}
 
 	const QString &key() const {return _key;}
 	QPoint xy() const {return _rect.topLeft();}
 	const QPixmap &pixmap() const {return _pixmap;}
+	bool isValid() const {return _valid;}
 
 	void render();
 
 private:
+	QPointF ll2xy(const Coordinates &c) const
+	  {return _transform.proj2img(_proj.ll2xy(c));}
 	void ll2xy(QList<MapData::Poly> &polys);
 	void ll2xy(QList<MapData::Point> &points);
 
@@ -42,7 +49,8 @@ private:
 	void processShields(QList<TextItem*> &textItems);
 	void processStreetNames(QList<TextItem*> &textItems);
 
-	IMGMap *_map;
+	Projection _proj;
+	Transform _transform;
 	const Style *_style;
 	int _zoom;
 	QRect _rect;
@@ -52,6 +60,7 @@ private:
 	QList<MapData::Poly> _polygons;
 	QList<MapData::Poly> _lines;
 	QList<MapData::Point> _points;
+	bool _valid;
 };
 
 }

src/map/imgmap.cpp

@@ -100,6 +100,8 @@ int IMGMap::zoomFit(const QSize &size, const RectC &rect)
 
 int IMGMap::zoomIn()
 {
+	cancelJobs();
+
 	_zoom = qMin(_zoom + 1, _data.first()->zooms().max());
 	updateTransform();
 	return _zoom;
@@ -107,6 +109,8 @@ int IMGMap::zoomIn()
 
 int IMGMap::zoomOut()
 {
+	cancelJobs();
+
 	_zoom = qMax(_zoom - 1, _data.first()->zooms().min());
 	updateTransform();
 	return _zoom;
@@ -139,6 +143,53 @@ void IMGMap::updateTransform()
 		_bounds.adjust(0.5, 0, -0.5, 0);
 }
 
+bool IMGMap::isRunning(const QString &key) const
+{
+	for (int i = 0; i < _jobs.size(); i++) {
+		const QList<IMG::RasterTile> &tiles = _jobs.at(i)->tiles();
+		for (int j = 0; j < tiles.size(); j++)
+			if (tiles.at(j).key() == key)
+				return true;
+	}
+
+	return false;
+}
+
+void IMGMap::runJob(IMGMapJob *job)
+{
+	_jobs.append(job);
+
+	connect(job, &IMGMapJob::finished, this, &IMGMap::jobFinished);
+	job->run();
+}
+
+void IMGMap::removeJob(IMGMapJob *job)
+{
+	_jobs.removeOne(job);
+	job->deleteLater();
+}
+
+void IMGMap::jobFinished(IMGMapJob *job)
+{
+	const QList<IMG::RasterTile> &tiles = job->tiles();
+
+	for (int i = 0; i < tiles.size(); i++) {
+		const IMG::RasterTile &mt = tiles.at(i);
+		if (mt.isValid())
+			QPixmapCache::insert(mt.key(), mt.pixmap());
+	}
+
+	removeJob(job);
+
+	emit tilesLoaded();
+}
+
+void IMGMap::cancelJobs()
+{
+	for (int i = 0; i < _jobs.size(); i++)
+		_jobs.at(i)->cancel();
+}
+
 void IMGMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 {
 	Q_UNUSED(flags);
@@ -159,6 +210,9 @@ void IMGMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 				QString key(_data.at(n)->fileName() + "-" + QString::number(_zoom)
 				  + "_" + QString::number(ttl.x()) + "_" + QString::number(ttl.y()));
 
+				if (isRunning(key))
+					continue;
+
 				if (QPixmapCache::find(key, &pm))
 					painter->drawPixmap(ttl, pm);
 				else {
@@ -182,7 +236,8 @@ void IMGMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 					_data.at(n)->points(pointRectD.toRectC(_projection, 20),
 					  _zoom, &points);
 
-					tiles.append(RasterTile(this, _data.at(n)->style(), _zoom,
+					tiles.append(RasterTile(_projection, _transform,
+					  _data.at(n)->style(), _zoom,
 					  QRect(ttl, QSize(TILE_SIZE, TILE_SIZE)), _tileRatio, key,
 					  polygons, lines, points));
 				}
@@ -190,6 +245,8 @@ void IMGMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 		}
 	}
 
+	if (!tiles.isEmpty()) {
+		if (flags & Map::Block) {
 			QFuture<void> future = QtConcurrent::map(tiles, &RasterTile::render);
 			future.waitForFinished();
 
@@ -199,6 +256,9 @@ void IMGMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 				painter->drawPixmap(mt.xy(), pm);
 				QPixmapCache::insert(mt.key(), pm);
 			}
+		} else
+			runJob(new IMGMapJob(tiles));
+	}
 }
 
 void IMGMap::setDevicePixelRatio(qreal deviceRatio, qreal mapRatio)

src/map/imgmap.h

@@ -1,12 +1,44 @@
 #ifndef IMGMAP_H
 #define IMGMAP_H
 
+#include <QtConcurrent>
 #include "map.h"
 #include "projection.h"
 #include "transform.h"
 #include "IMG/mapdata.h"
+#include "IMG/rastertile.h"
 
 
+class IMGMapJob : public QObject
+{
+	Q_OBJECT
+
+public:
+	IMGMapJob(const QList<IMG::RasterTile> &tiles)
+	  : _tiles(tiles) {}
+
+	void run()
+	{
+		connect(&_watcher, &QFutureWatcher<void>::finished, this,
+		  &IMGMapJob::handleFinished);
+		_future = QtConcurrent::map(_tiles, &IMG::RasterTile::render);
+		_watcher.setFuture(_future);
+	}
+	void cancel() {_future.cancel();}
+	const QList<IMG::RasterTile> &tiles() const {return _tiles;}
+
+signals:
+	void finished(IMGMapJob *job);
+
+private slots:
+	void handleFinished() {emit finished(this);}
+
+private:
+	QFutureWatcher<void> _watcher;
+	QFuture<void> _future;
+	QList<IMG::RasterTile> _tiles;
+};
+
 class IMGMap : public Map
 {
 	Q_OBJECT
@@ -44,9 +76,16 @@ public:
 
 	static Map* create(const QString &path, const Projection &, bool *isDir);
 
+private slots:
+	void jobFinished(IMGMapJob *job);
+
 private:
 	Transform transform(int zoom) const;
 	void updateTransform();
+	bool isRunning(const QString &key) const;
+	void runJob(IMGMapJob *job);
+	void removeJob(IMGMapJob *job);
+	void cancelJobs();
 
 	QList<IMG::MapData *> _data;
 	int _zoom;
@@ -56,6 +95,8 @@ private:
 	RectC _dataBounds;
 	qreal _tileRatio;
 
+	QList<IMGMapJob*> _jobs;
+
 	bool _valid;
 	QString _errorString;
 };