private static ImageSource CreateImage(TileSource tileSource, Tile tile)
{
ImageSource image = null;
try
{
image = BitmapFrame.Create(tileSource.GetUri(tile.XIndex, tile.Y, tile.ZoomLevel));
}
catch (Exception ex)
{
Trace.TraceWarning("Creating tile image failed: {0}", ex.Message);
}
return(image);
}
private void LoadPendingTiles(Dispatcher dispatcher, TileSource tileSource, string sourceName, bool animateOpacity)
{
var setImageAction = new Action <Tile, ImageSource>((t, i) => t.SetImageSource(i, animateOpacity));
var imageTileSource = tileSource as ImageTileSource;
Tile tile;
while (pendingTiles.TryDequeue(out tile))
{
byte[] buffer = null;
ImageSource image = null;
if (imageTileSource != null)
{
image = LoadImage(imageTileSource, tile);
}
else
{
var uri = tileSource.GetUri(tile.XIndex, tile.Y, tile.ZoomLevel);
if (uri != null)
{
if (uri.Scheme == "file") // create from FileStream as creating from URI leaves the file open
{
image = CreateImage(uri.AbsolutePath);
}
else
{
buffer = DownloadImage(uri);
image = CreateImage(buffer);
}
}
}
if (image != null || !tile.HasImageSource) // do not set null if tile already has an image (from cache)
{
dispatcher.BeginInvoke(setImageAction, DispatcherPriority.Render, tile, image);
}
if (buffer != null && image != null)
{
Cache.Set(GetCacheKey(sourceName, tile), buffer, new CacheItemPolicy {
SlidingExpiration = CacheExpiration
});
}
}
Interlocked.Decrement(ref threadCount);
}
private void GetTiles(List <Tile> tiles, Dispatcher dispatcher, TileSource tileSource,
string sourceName, int maxDownloads, bool animateOpacity)
{
var imageTileSource = tileSource as ImageTileSource;
if (imageTileSource != null)
{
if (!imageTileSource.CanLoadAsync) // call LoadImage in UI thread
{
var setImageAction = new Action <Tile, ImageTileSource>((t, ts) => t.SetImageSource(LoadImage(ts, t), animateOpacity));
foreach (var tile in tiles)
{
dispatcher.BeginInvoke(setImageAction, DispatcherPriority.Render, tile, imageTileSource);
}
return;
}
}
else if (!tileSource.UriFormat.StartsWith("file:")) // load local image files asynchronously, without caching
{
if (Cache == null || string.IsNullOrWhiteSpace(sourceName))
{
// no caching here: use default asynchronous downloading and caching done by WPF
var setImageAction = new Action <Tile, TileSource>((t, ts) => t.SetImageSource(CreateImage(ts, t), animateOpacity));
foreach (var tile in tiles)
{
dispatcher.BeginInvoke(setImageAction, DispatcherPriority.Render, tile, tileSource);
}
return;
}
else
{
var setImageAction = new Action <Tile, ImageSource>((t, i) => t.SetImageSource(i, animateOpacity));
var outdatedTiles = new List <Tile>(tiles.Count);
foreach (var tile in tiles)
{
var key = GetCacheKey(sourceName, tile);
var buffer = Cache.Get(key) as byte[];
var image = CreateImage(buffer);
if (image != null)
{
var creationTime = BitConverter.ToInt64(buffer, 0);
if (DateTime.FromBinary(creationTime) + CacheUpdateAge < DateTime.UtcNow)
{
dispatcher.Invoke(setImageAction, DispatcherPriority.Render, tile, image); // synchronously before enqueuing
outdatedTiles.Add(tile); // update outdated cache
}
else
{
dispatcher.BeginInvoke(setImageAction, DispatcherPriority.Render, tile, image);
}
}
else
{
pendingTiles.Enqueue(tile); // not yet cached
}
}
tiles = outdatedTiles; // enqueue outdated tiles at last
}
}
foreach (var tile in tiles)
{
pendingTiles.Enqueue(tile);
}
while (threadCount < Math.Min(pendingTiles.Count, maxDownloads))
{
Interlocked.Increment(ref threadCount);
ThreadPool.QueueUserWorkItem(o => LoadPendingTiles(dispatcher, tileSource, sourceName, animateOpacity));
}
}