Added support for downloading DEM tiles

src/data/demloader.cpp

@@ -0,0 +1,102 @@
+#include <QtMath>
+#include <QDir>
+#include <QFileInfo>
+#include "common/rectc.h"
+#include "demloader.h"
+
+
+#define DOWNLOAD_LIMIT 32
+
+static QList<DEM::Tile> tiles(const RectC &rect)
+{
+	QList<DEM::Tile> list;
+
+	if (!rect.isValid())
+		return list;
+
+	for (int i = qFloor(rect.top()); i >= qFloor(rect.bottom()); i--)
+		for (int j = qFloor(rect.left()); j <= qFloor(rect.right()); j++)
+			list.append(DEM::Tile(j, i));
+
+	return list;
+}
+
+static bool isZip(const QUrl &url)
+{
+	QFileInfo fi(url.fileName());
+	return (fi.suffix().toLower() == "zip");
+}
+
+
+DEMLoader::DEMLoader(const QString &dir, QObject *parent)
+  : QObject(parent), _dir(dir)
+{
+	_downloader = new Downloader(this);
+	connect(_downloader, &Downloader::finished, this, &DEMLoader::finished);
+}
+
+bool DEMLoader::loadTiles(const RectC &rect)
+{
+	QList<DEM::Tile> tl(tiles(rect));
+	QList<Download> dl;
+
+	/* Create the user DEM dir only when a download is requested as it will
+	   override the global DEM dir. */
+	if (!QDir().mkpath(_dir)) {
+		qWarning("%s: %s", qPrintable(_dir), "Error creating DEM directory");
+		return false;
+	}
+	/* This also clears the DEM data cache which is necessary to use the data
+	   from the downloaded DEM tiles. */
+	DEM::setDir(_dir);
+
+	for (int i = 0; i < tl.size(); i++) {
+		const DEM::Tile &t = tl.at(i);
+		QString fn(tileFile(t));
+		QString zn(fn + ".zip");
+
+		if (!(QFileInfo(zn).exists() || QFileInfo(fn).exists())) {
+			QUrl url(tileUrl(t));
+			dl.append(Download(url, isZip(url) ? zn : fn));
+		}
+	}
+
+	if (dl.size() > DOWNLOAD_LIMIT) {
+		qWarning("DEM download limit exceeded. Limit/requested: %u/%u.",
+		  DOWNLOAD_LIMIT, dl.size());
+		return false;
+	}
+
+	return _downloader->get(dl, _authorization);
+}
+
+bool DEMLoader::checkTiles(const RectC &rect) const
+{
+	QList<DEM::Tile> tl(tiles(rect));
+
+	for (int i = 0; i < tl.size(); i++) {
+		const DEM::Tile &t = tl.at(i);
+		QString fn(tileFile(t));
+		QString zn(fn + ".zip");
+
+		if (!(QFileInfo(zn).exists() || QFileInfo(fn).exists()))
+			return false;
+	}
+
+	return true;
+}
+
+QUrl DEMLoader::tileUrl(const DEM::Tile &tile) const
+{
+	QString url(_url);
+
+	url.replace("$lon", tile.lonStr());
+	url.replace("$lat", tile.latStr());
+
+	return QUrl(url);
+}
+
+QString DEMLoader::tileFile(const DEM::Tile &tile) const
+{
+	return _dir + QLatin1Char('/') + tile.baseName();
+}