Simple prefetch scheme

Prefetches larger set of tiles when camera is stopped

QTBUG-25136

Prefetch implementation including zoom-level prefetching
Two prefetching options- pan buffer, or pan buffer for two nearest zoom levels
Code simplified by removing all three visibleTiles lists, so they can't go out of sync
Textures not promoted up the cache if they aren't visible when retrieved from server

Also: Prefetch on map initialize + optimisation

This ensures that the prefetch is called at the end of initialisation
Useful if the location is not already in disk cache. And makes no
difference if it is already in disk cache.
QTBUG-25786

Change-Id: Ife7c1d103f83695659f4534880268fa5afd8f7c7
Reviewed-by: Alex Wilson <alex.wilson@nokia.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/location/maps/qgeomap.cpp b/src/location/maps/qgeomap.cpp
index 7001c7c7..ad81fd13 100644
--- a/src/location/maps/qgeomap.cpp
+++ b/src/location/maps/qgeomap.cpp
@@ -129,6 +129,11 @@ void QGeoMap::setCameraData(const QGeoCameraData &cameraData)
     mapData_->setCameraData(cameraData);
 }
 
+void QGeoMap::cameraStopped()
+{
+    mapData_->prefetchData();
+}
+
 QGeoCameraData QGeoMap::cameraData() const
 {
     return mapData_->cameraData();