MapView scale less detailed levels on current level feature

libs/map/mapview.cpp

@@ -66,6 +66,7 @@ QPointF MapView::center() const {
 
 void MapView::setCenter(QPointF c) {
 	center_ = OSM::geo2xy(c);
+	checkCenter();
 	updateViewRect();
 	drawBackground();
 }
@@ -100,6 +101,7 @@ void MapView::mouseMoveEvent(QMouseEvent * e) {
 		if (is_pan) {
 			double mins = qMin(width(), height());
 			center_ -= QPointF(e->pos() - press_point) / scale_ / mins;
+			checkCenter();
 			press_point = e->pos();
 			updateViewRect();
 			drawBackground();
@@ -133,7 +135,7 @@ void MapView::paintEvent(QPaintEvent *) {
 
 
 void MapView::resizeEvent(QResizeEvent *) {
-	cache->setMinimumCacheSize((width() + tileSize) * (height() + tileSize) * 4);
+	cache->setMinimumCacheSize((width() + tileSize) * (height() + tileSize) * 4 * 3);
 	checkZoom();
 	updateZoomLevel();
 	updateViewRect();
@@ -158,9 +160,10 @@ void MapView::drawBackground() {
 		for (int iy = sy; iy < ey; ++iy) {
 			QRectF r((ix)*ts, (iy)*ts, ts, ts);
 			r.translate(-offset);
-			auto tile = cache->getTile((OSM::TileIndex){zoom_level, ix, iy});
+			QRectF px_rct(QPointF(), QSizeF(tileSize, tileSize));
+			auto tile = cache->getTile((OSM::TileIndex){zoom_level, ix, iy}, px_rct);
 			if (!tile.isEmpty()) {
-				p.drawPixmap(r, tile.pixmap, QRectF(tile.pixmap.rect()));
+				p.drawPixmap(r, tile.pixmap, px_rct);
 			} else {
 				p.fillRect(r, brush_tr);
 			}
@@ -212,6 +215,14 @@ void MapView::checkZoom() {
 }
 
 
+void MapView::checkCenter() {
+	if (center_.x() < 0.) center_.setX(0.);
+	if (center_.x() > 1.) center_.setX(1.);
+	if (center_.y() < 0.) center_.setY(0.);
+	if (center_.y() > 1.) center_.setY(1.);
+}
+
+
 void MapView::zoomLevelChanged(int new_level) {
 	zoom_level = qBound(0, new_level, max_level);
 	// qDebug() << "level changed" << new_level << zoom_level;
@@ -296,7 +307,8 @@ void MapView::zoom(double factor, QPoint anchor) {
 	checkZoom();
 	QPointF new_center = mapToNorm(anchor);
 	center_ += prev_center - new_center;
-	view_rect.translate(prev_center - new_center);
+	checkCenter();
+	view_rect.moveCenter(center_);
 	updateZoomLevel();
 	drawBackground();
 }
@@ -312,6 +324,7 @@ void MapView::zoomTo(double level) {
 
 void MapView::centerTo(QPointF coord) {
 	center_ = OSM::geo2xy(coord);
+	checkCenter();
 	updateViewRect();
 	drawBackground();
 }

libs/map/mapview.h

@@ -64,6 +64,7 @@ private:
 	void drawBackground();
 	void drawItems(QPainter & p);
 	void checkZoom();
+	void checkCenter();
 	void zoomLevelChanged(int new_level);
 	void updateZoomLevel();
 	void updateViewRect();

libs/map/osm_tile_cache.cpp

@@ -32,7 +32,32 @@ void OSMTileCache::tileDownloaded(OSM::TileIndex index, const QPixmap & pixmap)
 }
 
 
-OSM::TilePixmap OSMTileCache::getTile(OSM::TileIndex index) {
+OSM::TilePixmap OSMTileCache::getTile(OSM::TileIndex index, QRectF & rect_src) {
+	OSM::TilePixmap ret = getTileFromCache(index);
+	if (ret.isEmpty()) {
+		parent->downloader->queueTile(index);
+		QVector<QPointF> offsets;
+		while (index.z >= 0) {
+			index.z--;
+			offsets << QPointF(index.x % 2, index.y % 2);
+			index.x /= 2;
+			index.y /= 2;
+			ret = getTileFromCache(index);
+			if (!ret.isEmpty()) {
+				for (int i = offsets.size() - 1; i >= 0; --i) {
+					rect_src.setSize(rect_src.size() / 2.);
+					rect_src.translate(offsets[i].x() * rect_src.width(), offsets[i].y() * rect_src.height());
+				}
+				return ret;
+			}
+		}
+	} else
+		rect_src = ret.pixmap.rect();
+	return ret;
+}
+
+
+OSM::TilePixmap OSMTileCache::getTileFromCache(OSM::TileIndex index) {
 	OSM::TilePixmap ret;
 	ret.index   = index;
 	auto * tile = tile_cache[index.hash()];
@@ -51,7 +76,6 @@ OSM::TilePixmap OSMTileCache::getTile(OSM::TileIndex index) {
 				return ret;
 			}
 		}
-		parent->downloader->queueTile(index);
 	}
 	return ret;
 }

libs/map/osm_tile_cache_p.h

@@ -48,9 +48,10 @@ public:
 	}
 
 	void tileDownloaded(OSM::TileIndex index, const QPixmap & pixmap);
-	OSM::TilePixmap getTile(OSM::TileIndex index);
+	OSM::TilePixmap getTile(OSM::TileIndex index, QRectF & rect_src);
 
 private:
+	OSM::TilePixmap getTileFromCache(OSM::TileIndex index);
 	void updateCacheSize();
 	void saveTile(OSM::TilePixmap * tile);
 	void writeToDisk(const OSM::TilePixmap & tile);

utils/mapviewer/main.cpp

@@ -67,6 +67,6 @@ int main(int argc, char * argv[]) {
 	w.addItem(it);
 	w.addItem(ell);*/
 	w.centerTo({55.583055, 37.580008});
-	w.zoomTo(17);
+	w.zoomTo(2);
 	return a.exec();
 }