/// <summary>
/// Updates each map item in the set, setting whether it's in the view specified by the given
/// location rect and zoom level.
/// </summary>
/// <param name="locationRect">The location rect component of the view.</param>
/// <param name="zoomLevel">The zoom level component of the view.</param>
public override void UpdateVisibilty(LocationRect locationRect, int zoomLevel)
{
// If the location rect has no area...
if (locationRect.Width <= 0 || locationRect.Height <= 0)
{
// ...then clear the visibility on each map item.
foreach (MapItem item in _Items)
{
item.InView = false;
}
}
else
{
// ...otherwise, do the normal visibility update.
NormalizedMercatorRect queryRect = new NormalizedMercatorRect(locationRect);
foreach (MapItem item in _Items)
{
bool inView = false;
if (zoomLevel <= item.MaxZoomLevel && zoomLevel >= item.MinZoomLevel)
{
NormalizedMercatorRect itemRect = item.BoundingRectAtZoomLevel(zoomLevel);
if (queryRect.Intersects(itemRect))
{
inView = true;
}
}
item.InView = inView;
}
}
}
/// <summary>
/// Returns all of the items that intersect the given rect at the given zoom level. This list
/// may contain duplicate items.
/// </summary>
/// <param name="rect">The rect.</param>
/// <param name="zoomLevel">The zoom level.</param>
/// <returns></returns>
public IEnumerable<MapItem> IntersectingItems(NormalizedMercatorRect rect, int zoomLevel)
{
if (zoomLevel < 0)
{
throw new ArgumentException("zoom level must be non-negative");
}
if (!rect.Intersects(_RootNode.Rect))
{
throw new ArgumentException("rect out of range");
}
int nodesVisited = 0;
Debug.Assert(_NodesToVisit.Count == 0);
_NodesToVisit.Push(_RootNode);
for (; _NodesToVisit.Count > 0; nodesVisited++)
{
MapItemQuadTreeNode node = _NodesToVisit.Pop();
Debug.Assert(node.ZoomLevel <= zoomLevel);
Debug.Assert(rect.Intersects(node.Rect));
if (zoomLevel == node.ZoomLevel)
{
foreach (MapItem item in node.Items)
{
if (item.BoundingRectAtZoomLevel(node.ZoomLevel).Intersects(rect))
{
yield return item;
}
}
}
else
{
for (int childIdx = 0; childIdx < 4; childIdx++)
{
MapItemQuadTreeNode child = node.GetChild(childIdx);
if (child != null && rect.Intersects(child.Rect))
{
_NodesToVisit.Push(child);
}
}
}
}
}
