public IList <TileInfo> GetTilesWanted(TileSchema schema, Extent extent, int level)
{
IList <TileInfo> infos = new List <TileInfo>();
int step = 1;
// Iterating through all levels from current to zero. If lower levels are
// not availeble the renderer can fall back on higher level tiles.
while (level >= 0)
{
IList <TileInfo> infosOfLevel = schema.GetTilesInView(extent, level);
infosOfLevel = PrioritizeTiles(infosOfLevel, extent.CenterX, extent.CenterY, sorter);
foreach (TileInfo info in infosOfLevel)
{
if ((info.Index.Row >= 0) && (info.Index.Col >= 0))
{
infos.Add(info);
}
}
level = level - step;
step++;
}
return(infos);
}
private void DrawRecursive(Canvas canvas, TileSchema schema, ITransform transform, MemoryCache <MemoryStream> memoryCache, Extent extent, int level)
{
IList <TileInfo> tiles = schema.GetTilesInView(extent, level);
foreach (TileInfo tile in tiles)
{
MemoryStream image = memoryCache.Find(tile.Index);
if (image == null)
{
if (level > 0)
{
DrawRecursive(canvas, schema, transform, memoryCache, tile.Extent.Intersect(extent), level - 1);
}
}
else
{
Rect dest = MapTransformHelper.WorldToMap(tile.Extent, transform);
double opacity = DrawImage(canvas, image, dest, tile);
if ((opacity < 1) && (level > 0))
{
DrawRecursive(canvas, schema, transform, memoryCache, tile.Extent.Intersect(extent), level - 1);
}
}
}
}
public IEnumerable <TileInfo> GetTilesInView(Extent extent, string levelId)
{
return(TileSchema.GetTilesInView(this, extent, levelId));
}
