Render MBTiles maps asynchronous if they include vector tiles

src/map/mbtilesmap.cpp

@@ -4,8 +4,6 @@
 #include <QSqlError>
 #include <QPainter>
 #include <QPixmapCache>
-#include <QImageReader>
-#include <QBuffer>
 #include <QtConcurrent>
 #include "common/util.h"
 #include "osm.h"
@@ -14,37 +12,6 @@
 
 #define META_TYPE(type) static_cast<QMetaType::Type>(type)
 
-class MBTile
-{
-public:
-	MBTile(int zoom, int scaledSize, const QPoint &xy, const QByteArray &data,
-	  const QString &key) : _zoom(zoom), _scaledSize(scaledSize), _xy(xy),
-	  _data(data), _key(key) {}
-
-	const QPoint &xy() const {return _xy;}
-	const QString &key() const {return _key;}
-	const QPixmap &pixmap() const {return _pixmap;}
-
-	void load() {
-		QByteArray z(QString::number(_zoom).toLatin1());
-
-		QBuffer buffer(&_data);
-		QImageReader reader(&buffer, z);
-		if (_scaledSize)
-			reader.setScaledSize(QSize(_scaledSize, _scaledSize));
-		_pixmap = QPixmap::fromImage(reader.read());
-	}
-
-private:
-	int _zoom;
-	int _scaledSize;
-	QPoint _xy;
-	QByteArray _data;
-	QString _key;
-	QPixmap _pixmap;
-};
-
-
 MBTilesMap::MBTilesMap(const QString &fileName, QObject *parent)
   : Map(fileName, parent), _mapRatio(1.0), _tileRatio(1.0), _scalable(false),
   _scaledSize(0), _valid(false)
@@ -183,6 +150,7 @@ void MBTilesMap::load(const Projection &in, const Projection &out,
 
 void MBTilesMap::unload()
 {
+	cancelJobs(true);
 	_db.close();
 }
 
@@ -219,12 +187,16 @@ qreal MBTilesMap::resolution(const QRectF &rect)
 
 int MBTilesMap::zoomIn()
 {
+	cancelJobs(false);
+
 	_zi = qMin(_zi + 1, _zooms.size() - 1);
 	return _zi;
 }
 
 int MBTilesMap::zoomOut()
 {
+	cancelJobs(false);
+
 	_zi = qMax(_zi - 1, 0);
 	return _zi;
 }
@@ -260,6 +232,53 @@ QByteArray MBTilesMap::tileData(int zoom, const QPoint &tile) const
 	return QByteArray();
 }
 
+bool MBTilesMap::isRunning(const QString &key) const
+{
+	for (int i = 0; i < _jobs.size(); i++) {
+		const QList<MBTile> &tiles = _jobs.at(i)->tiles();
+		for (int j = 0; j < tiles.size(); j++)
+			if (tiles.at(j).key() == key)
+				return true;
+	}
+
+	return false;
+}
+
+void MBTilesMap::runJob(MBTilesMapJob *job)
+{
+	_jobs.append(job);
+
+	connect(job, &MBTilesMapJob::finished, this, &MBTilesMap::jobFinished);
+	job->run();
+}
+
+void MBTilesMap::removeJob(MBTilesMapJob *job)
+{
+	_jobs.removeOne(job);
+	job->deleteLater();
+}
+
+void MBTilesMap::jobFinished(MBTilesMapJob *job)
+{
+	const QList<MBTile> &tiles = job->tiles();
+
+	for (int i = 0; i < tiles.size(); i++) {
+		const MBTile &mt = tiles.at(i);
+		if (!mt.pixmap().isNull())
+			QPixmapCache::insert(mt.key(), mt.pixmap());
+	}
+
+	removeJob(job);
+
+	emit tilesLoaded();
+}
+
+void MBTilesMap::cancelJobs(bool wait)
+{
+	for (int i = 0; i < _jobs.size(); i++)
+		_jobs.at(i)->cancel(wait);
+}
+
 void MBTilesMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 {
 	Q_UNUSED(flags);
@@ -288,6 +307,9 @@ void MBTilesMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 			QString key = path() + "-" + QString::number(zoom) + "_"
 			  + QString::number(t.x()) + "_" + QString::number(t.y());
 
+			if (isRunning(key))
+				continue;
+
 			if (QPixmapCache::find(key, &pm)) {
 				QPointF tp(qMax(tl.x(), b.left()) + (t.x() - tile.x())
 				  * tileSize(), qMax(tl.y(), b.top()) + (t.y() - tile.y())
@@ -300,6 +322,8 @@ void MBTilesMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 		}
 	}
 
+	if (!tiles.isEmpty()) {
+		if (flags & Map::Block || !_scalable) {
 			QFuture<void> future = QtConcurrent::map(tiles, &MBTile::load);
 			future.waitForFinished();
 
@@ -316,6 +340,9 @@ void MBTilesMap::draw(QPainter *painter, const QRectF &rect, Flags flags)
 				  * tileSize());
 				drawTile(painter, pm, tp);
 			}
+		} else
+			runJob(new MBTilesMapJob(tiles));
+	}
 }
 
 void MBTilesMap::drawTile(QPainter *painter, QPixmap &pixmap, QPointF &tp)

src/map/mbtilesmap.h

@@ -3,10 +3,80 @@
 
 #include <QSqlDatabase>
 #include <QVector>
+#include <QImageReader>
+#include <QBuffer>
+#include <QPixmap>
+#include <QtConcurrent>
 #include "map.h"
 
+class MBTile
+{
+public:
+	MBTile(int zoom, int scaledSize, const QPoint &xy, const QByteArray &data,
+	  const QString &key) : _zoom(zoom), _scaledSize(scaledSize), _xy(xy),
+	  _data(data), _key(key) {}
+
+	const QPoint &xy() const {return _xy;}
+	const QString &key() const {return _key;}
+	const QPixmap &pixmap() const {return _pixmap;}
+
+	void load() {
+		QByteArray z(QString::number(_zoom).toLatin1());
+
+		QBuffer buffer(&_data);
+		QImageReader reader(&buffer, z);
+		if (_scaledSize)
+			reader.setScaledSize(QSize(_scaledSize, _scaledSize));
+		_pixmap = QPixmap::fromImage(reader.read());
+	}
+
+private:
+	int _zoom;
+	int _scaledSize;
+	QPoint _xy;
+	QByteArray _data;
+	QString _key;
+	QPixmap _pixmap;
+};
+
+class MBTilesMapJob : public QObject
+{
+	Q_OBJECT
+
+public:
+	MBTilesMapJob(const QList<MBTile> &tiles) : _tiles(tiles) {}
+
+	void run()
+	{
+		connect(&_watcher, &QFutureWatcher<void>::finished, this,
+		  &MBTilesMapJob::handleFinished);
+		_future = QtConcurrent::map(_tiles, &MBTile::load);
+		_watcher.setFuture(_future);
+	}
+	void cancel(bool wait)
+	{
+		_future.cancel();
+		if (wait)
+			_future.waitForFinished();
+	}
+	const QList<MBTile> &tiles() const {return _tiles;}
+
+signals:
+	void finished(MBTilesMapJob *job);
+
+private slots:
+	void handleFinished() {emit finished(this);}
+
+private:
+	QFutureWatcher<void> _watcher;
+	QFuture<void> _future;
+	QList<MBTile> _tiles;
+};
+
 class MBTilesMap : public Map
 {
+	Q_OBJECT
+
 public:
 	MBTilesMap(const QString &fileName, QObject *parent = 0);
 
@@ -36,12 +106,19 @@ public:
 
 	static Map *create(const QString &path, const Projection &proj, bool *isDir);
 
+private slots:
+	void jobFinished(MBTilesMapJob *job);
+
 private:
 	qreal tileSize() const;
 	qreal coordinatesRatio() const;
 	qreal imageRatio() const;
 	QByteArray tileData(int zoom, const QPoint &tile) const;
 	void drawTile(QPainter *painter, QPixmap &pixmap, QPointF &tp);
+	bool isRunning(const QString &key) const;
+	void runJob(MBTilesMapJob *job);
+	void removeJob(MBTilesMapJob *job);
+	void cancelJobs(bool wait);
 
 	QSqlDatabase _db;
 
@@ -54,6 +131,8 @@ private:
 	bool _scalable;
 	int _scaledSize;
 
+	QList<MBTilesMapJob*> _jobs;
+
 	bool _valid;
 	QString _errorString;
 };