Add %4 option in url, to enhance multi-source downloading

for a.tile.openstreetmap.org\b.tile.openstreetmap.org
c.tile.openstreetmap.org
using Y % 3 == 0,1,2 ->a,b,c

qtviewer_planetosm/osmtiles/layer_tiles.cpp

@@ -26,7 +26,7 @@ namespace QTVOSM{
 		m_downloadThread->start();
 		//!2,init basic cache and server site.if user does not give address, default set to "http://localhost/osm/%1/%2/%3.png"
 		this->m_strLocalCache = "/OSMCache";
-		this->m_strServerURL = "http://c.tile.openstreetmap.org/%1/%2/%3.png";
+		this->m_strServerURL = "http://%4.tile.openstreetmap.org/%1/%2/%3.png";
 		m_bconnected = false;
 		m_propPage = 0;
 		//!3, init the Drag position, for mouse drag and explore.
@@ -137,7 +137,7 @@ namespace QTVOSM{
 		{
 			this->m_nStartPosX = event->pos().x();
 			this->m_nStartPosY = event->pos().y();
-		}		
+		}
 		return res;
 	}
 
@@ -212,7 +212,7 @@ namespace QTVOSM{
 		connect(m_downloader,SIGNAL(evt_all_taskFinished()),this,SLOT(updateViewer()));
 		//Get Cache Address
 		QSettings settings(QCoreApplication::applicationFilePath()+".ini",QSettings::IniFormat);
-		m_strServerURL = settings.value(QString("settings/ServerURL_%1").arg(m_name),"http://c.tile.openstreetmap.org/%1/%2/%3.png").toString();
+		m_strServerURL = settings.value(QString("settings/ServerURL_%1").arg(m_name),"http://%4.tile.openstreetmap.org/%1/%2/%3.png").toString();
 		m_strLocalCache = settings.value(QString("settings/LocalCache_%1").arg(m_name), QCoreApplication::applicationDirPath() +"/OSMCache").toString();
 		m_nCacheExpireDays = settings.value(QString("settings/CacheExpireDays_%1").arg(m_name), 30).toInt();
 		return this;
@@ -350,7 +350,11 @@ namespace QTVOSM{
 		LFix += ".png";
 		strFileName = QString::number(nY,10);
 		strFileName += ".png";
-		strSourceUrl = m_strServerURL.arg(nLevel).arg(nX).arg(nY);
+		QChar mirr[3] = {QChar('a'),QChar('b'),QChar('c')};
+		if (m_strServerURL.contains("%4"))
+			strSourceUrl = m_strServerURL.arg(nLevel).arg(nX).arg(nY).arg(mirr[nY%3]);
+		else
+			strSourceUrl = m_strServerURL.arg(nLevel).arg(nX).arg(nY);
 
 		this->m_downloader->addDownloadUrl(strSourceUrl,strDestinDir,strFileName);
 		return true;

qtviewer_planetosm/osmtiles/layer_tiles_page.cpp

@@ -15,7 +15,7 @@ namespace QTVOSM{
 		ui->setupUi(this);
 		//Get Cache Address
 		QSettings settings(QCoreApplication::applicationFilePath()+".ini",QSettings::IniFormat);
-		QString strServerURL = settings.value(QString("settings/ServerURL_%1").arg(layer->get_name()),"http://c.tile.openstreetmap.org/%1/%2/%3.png").toString();
+		QString strServerURL = settings.value(QString("settings/ServerURL_%1").arg(layer->get_name()),"http://%4.tile.openstreetmap.org/%1/%2/%3.png").toString();
 		QString strLocalCache = settings.value(QString("settings/LocalCache_%1").arg(layer->get_name()), QCoreApplication::applicationDirPath() +"/OSMCache").toString();
 		int nCacheExpireDays = settings.value(QString("settings/CacheExpireDays_%1").arg(layer->get_name()), 30).toInt();
 		int nAutoDownload = settings.value(QString("settings/nAutoDownload_%1").arg(layer->get_name()), 0).toInt();

qtviewer_planetosm/qtaxviewer_planetosm.cpp

@@ -73,7 +73,7 @@ void qtaxviewer_planetosm::osm_set_remote_address (QString layerName, QString ad
 
 QString qtaxviewer_planetosm::osm_get_remote_address(QString layerName) const
 {
-	QString res = "http://c.tile.openstreetmap.org/%1/%2/%3.png";
+	QString res = "http://%4.tile.openstreetmap.org/%1/%2/%3.png";
 	tilesviewer * pv = this->ui->widget_QTV_mainMap ;
 	layer_interface * la = pv->layer(layerName);
 	if (la)

qtviewer_planetosm/qtwidget_planetosm.cpp

@@ -96,7 +96,7 @@ void qtwidget_planetosm::osm_set_remote_address (QString layerName, QString addr
 
 QString qtwidget_planetosm::osm_get_remote_address(QString layerName) const
 {
-	QString res = "http://c.tile.openstreetmap.org/%1/%2/%3.png";
+	QString res = "http://%4.tile.openstreetmap.org/%1/%2/%3.png";
 	osm_frame_widget * mp = qobject_cast<osm_frame_widget *>(m_map_widget);tilesviewer * pv=mp->viewer();
 	layer_interface * la = pv->layer(layerName);
 	if (la)