Do not render tiles that will not be shown due to zoom in/out

src/map/mapsforge/rastertile.cpp

@@ -344,4 +344,6 @@ void RasterTile::render()
 	//painter.drawRect(QRect(_rect.topLeft(), _pixmap.size()));
 
 	qDeleteAll(textItems);
+
+	_valid = true;
 }

src/map/mapsforge/rastertile.h

@@ -16,15 +16,16 @@ class RasterTile
 {
 public:
 	RasterTile(const Projection &proj, const Transform &transform, int zoom,
-	  const QRect &rect, qreal ratio, const QString &key,
-	  const QList<MapData::Path> &paths, const QList<MapData::Point> &points)
-	  : _proj(proj), _transform(transform), _zoom(zoom), _rect(rect),
-	  _ratio(ratio), _key(key), _pixmap(rect.width() * ratio,
-	  rect.height() * ratio), _paths(paths), _points(points) {}
+	  const QRect &rect, qreal ratio, const QList<MapData::Path> &paths,
+	  const QList<MapData::Point> &points) : _proj(proj), _transform(transform),
+	  _zoom(zoom), _rect(rect), _ratio(ratio),
+	  _pixmap(rect.width() * ratio, rect.height() * ratio), _paths(paths),
+	  _points(points), _valid(false) {}
 
-	const QString &key() const {return _key;}
+	int zoom() const {return _zoom;}
 	QPoint xy() const {return _rect.topLeft();}
 	const QPixmap &pixmap() const {return _pixmap;}
+	bool isValid() const {return _valid;}
 
 	void render();
 
@@ -84,10 +85,10 @@ private:
 	int _zoom;
 	QRect _rect;
 	qreal _ratio;
-	QString _key;
 	QPixmap _pixmap;
 	QList<MapData::Path> _paths;
 	QList<MapData::Point> _points;
+	bool _valid;
 };
 
 inline HASH_T qHash(const RasterTile::Key &key)

src/map/mapsforgemap.cpp

@@ -60,6 +60,8 @@ int MapsforgeMap::zoomFit(const QSize &size, const RectC &rect)
 
 int MapsforgeMap::zoomIn()
 {
+	cancelJobs();
+
 	_zoom = qMin(_zoom + 1, _data.zooms().max());
 	updateTransform();
 	return _zoom;
@@ -67,6 +69,8 @@ int MapsforgeMap::zoomIn()
 
 int MapsforgeMap::zoomOut()
 {
+	cancelJobs();
+
 	_zoom = qMax(_zoom - 1, _data.zooms().min());
 	updateTransform();
 	return _zoom;
@@ -101,29 +105,59 @@ void MapsforgeMap::updateTransform()
 		_bounds.adjust(0.5, 0, -0.5, 0);
 }
 
-bool MapsforgeMap::isRunning(const QString &key) const
+bool MapsforgeMap::isRunning(int zoom, const QPoint &xy) const
 {
-	return _running.contains(key);
+	for (int i = 0; i < _jobs.size(); i++) {
+		const QList<Mapsforge::RasterTile> &tiles = _jobs.at(i)->tiles();
+		for (int j = 0; j < tiles.size(); j++) {
+			const Mapsforge::RasterTile &mt = tiles.at(j);
+			if (mt.zoom() == zoom && mt.xy() == xy)
+				return true;
+		}
 	}
 
-void MapsforgeMap::addRunning(const QList<RasterTile> &tiles)
-{
-	for (int i = 0; i < tiles.size(); i++)
-		_running.insert(tiles.at(i).key());
+	return false;
 }
 
-void MapsforgeMap::removeRunning(const QList<RasterTile> &tiles)
+void MapsforgeMap::runJob(MapsforgeMapJob *job)
 {
-	for (int i = 0; i < tiles.size(); i++)
-		_running.remove(tiles.at(i).key());
+	_jobs.append(job);
+
+	connect(job, &MapsforgeMapJob::finished, this, &MapsforgeMap::jobFinished);
+	job->run();
 }
 
-void MapsforgeMap::jobFinished(const QList<RasterTile> &tiles)
+void MapsforgeMap::removeJob(MapsforgeMapJob *job)
 {
-	removeRunning(tiles);
+	_jobs.removeOne(job);
+	job->deleteLater();
+}
+
+void MapsforgeMap::jobFinished(MapsforgeMapJob *job)
+{
+	const QList<Mapsforge::RasterTile> &tiles = job->tiles();
+
+	for (int i = 0; i < tiles.size(); i++) {
+		const Mapsforge::RasterTile &mt = tiles.at(i);
+		if (!mt.isValid())
+			continue;
+
+		QString key = path() + "-" + QString::number(mt.zoom()) + "_"
+		  + QString::number(mt.xy().x()) + "_" + QString::number(mt.xy().y());
+		QPixmapCache::insert(key, mt.pixmap());
+	}
+
+	removeJob(job);
+
 	emit tilesLoaded();
 }
 
+void MapsforgeMap::cancelJobs()
+{
+	for (int i = 0; i < _jobs.size(); i++)
+		_jobs.at(i)->cancel();
+}
+
 void MapsforgeMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 {
 	Q_UNUSED(flags);
@@ -138,15 +172,15 @@ void MapsforgeMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 
 	for (int i = 0; i < width; i++) {
 		for (int j = 0; j < height; j++) {
-			QPixmap pm;
 			QPoint ttl(tl.x() + i * _data.tileSize(), tl.y() + j
 			  * _data.tileSize());
+			if (isRunning(_zoom, ttl))
+				continue;
+
+			QPixmap pm;
 			QString key = path() + "-" + 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 {
@@ -175,18 +209,13 @@ void MapsforgeMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 
 				tiles.append(RasterTile(_projection, _transform, _zoom,
 				  QRect(ttl, QSize(_data.tileSize(), _data.tileSize())),
-				  _tileRatio, key, paths, points));
+				  _tileRatio, paths, points));
 			}
 		}
 	}
 
-	if (!tiles.isEmpty()) {
-		MapsforgeMapJob *job = new MapsforgeMapJob(tiles);
-		connect(job, &MapsforgeMapJob::finished, this,
-		  &MapsforgeMap::jobFinished);
-		addRunning(tiles);
-		job->run();
-	}
+	if (!tiles.isEmpty())
+		runJob(new MapsforgeMapJob(tiles));
 }
 
 void MapsforgeMap::setDevicePixelRatio(qreal deviceRatio, qreal mapRatio)

src/map/mapsforgemap.h

@@ -26,26 +26,14 @@ public:
 		_future = QtConcurrent::map(_tiles, &Mapsforge::RasterTile::render);
 		_watcher.setFuture(_future);
 	}
+	void cancel() {_future.cancel();}
+	const QList<Mapsforge::RasterTile> &tiles() const {return _tiles;}
 
 signals:
-	void finished(const QList<Mapsforge::RasterTile> &);
+	void finished(MapsforgeMapJob *job);
 
 private slots:
-	void handleFinished()
-	{
-		for (int i = 0; i < _tiles.size(); i++) {
-			Mapsforge::RasterTile &mt = _tiles[i];
-			const QPixmap &pm = mt.pixmap();
-			if (pm.isNull())
-				continue;
-
-			QPixmapCache::insert(mt.key(), pm);
-		}
-
-		emit finished(_tiles);
-
-		deleteLater();
-	}
+	void handleFinished() {emit finished(this);}
 
 private:
 	QFutureWatcher<void> _watcher;
@@ -85,14 +73,15 @@ public:
 	QString errorString() const {return _data.errorString();}
 
 private slots:
-	void jobFinished(const QList<Mapsforge::RasterTile> &tiles);
+	void jobFinished(MapsforgeMapJob *job);
 
 private:
 	Transform transform(int zoom) const;
 	void updateTransform();
-	bool isRunning(const QString &key) const;
-	void addRunning(const QList<Mapsforge::RasterTile> &tiles);
-	void removeRunning(const QList<Mapsforge::RasterTile> &tiles);
+	bool isRunning(int zoom, const QPoint &xy) const;
+	void runJob(MapsforgeMapJob *job);
+	void removeJob(MapsforgeMapJob *job);
+	void cancelJobs();
 
 	Mapsforge::MapData _data;
 	int _zoom;
@@ -102,7 +91,7 @@ private:
 	QRectF _bounds;
 	qreal _tileRatio;
 
-	QSet<QString> _running;
+	QList<MapsforgeMapJob*> _jobs;
 };
 
 #endif // MAPSFORGEMAP_H