/// <summary>
/// Asynchronously gets a tile image from the Bing maps REST service.
/// </summary>
/// <param name="requestInformation">The tile information which is to handle the request and receive the
/// image.</param>
/// <param name="centerCoordinate">The geo-coordinate which should serve as the image center.</param>
/// <param name="zoomLevel">The desired image zoom level.</param>
/// <param name="viewType">The desired image view type.</param>
void GetImageFromServer(TileInformation requestInformation, GeoCoordinate centerCoordinate, int zoomLevel,
BingMapsViewType viewType)
{
// Build the request URI according to the parameters
string requestUri = string.Format(
"http://dev.virtualearth.net/REST/V1/Imagery/Map/{4}/{0},{1}/{2}?mapSize={5},{6}&key={3}",
centerCoordinate.Latitude, centerCoordinate.Longitude, zoomLevel, BingMapKey, viewType,
(int)tileDimensions.X, (int)tileDimensions.Y);
// Launch the request
requestInformation.RequestImageAync(new Uri(requestUri, UriKind.Absolute));
pendingRequestCount++;
}
/// <summary>
/// Place images received from the REST service in the proper place in the active tile cube, and save them to
/// the cache.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void TileServerRequestCompleted(object sender, OpenReadCompletedEventArgs e)
{
pendingRequestCount--;
TileInformation requestInformation = (TileInformation)e.UserState;
// Do not handle the event if the request was cancelled
if (requestInformation.IsRequestCancelled)
{
requestInformation.MarkImageRequestCancelled();
if (pendingRequestCount == 0)
{
MoveToNextPhase();
}
return;
}
bool imageAvailable = e.Error == null ? true : false;
// Clean the old image, if any
requestInformation.Dispose(true);
try
{
if (imageAvailable == true)
{
SetTileImage(e, requestInformation);
}
}
catch (Exception)
{
imageAvailable = false;
}
if (imageAvailable == false)
{
requestInformation.Image = unavailableImage;
}
requestInformation.MarkImageRequestCompleted();
// If all asynchronous calls returned, we can move to the next phase
if (pendingRequestCount == 0)
{
MoveToNextPhase();
}
}
/// <summary>
/// Cancels all currently ongoing tile image requests, and disposes of all current tile images.
/// </summary>
private void CancelActiveRequestsAndResetImages()
{
for (int xIndex = 0; xIndex < ActiveTilePlaneSize; xIndex++)
{
for (int yIndex = 0; yIndex < ActiveTilePlaneSize; yIndex++)
{
TileInformation cellInformation = activeTilePlane[xIndex, yIndex];
if (cellInformation != null)
{
cellInformation.Dispose();
}
}
}
}
/// <summary>
/// Initializes the active tile plane by requesting images centered at the specified geo-coordinate.
/// </summary>
/// <param name="centerCoordinate">The geo-coordinate which will serve as the center of the
/// middle tile.</param>
private void GetActivePlaneImages(GeoCoordinate centerCoordinate)
{
Vector2 centerPixelXY = TileSystem.LatLongToPixelXY(centerCoordinate, zoomLevel);
int planeCenterIndex = PlaneCenterIndex;
for (int xIndex = 0; xIndex < ActiveTilePlaneSize; xIndex++)
{
int xDelta = xIndex - planeCenterIndex;
for (int yIndex = 0; yIndex < ActiveTilePlaneSize; yIndex++)
{
int yDelta = yIndex - planeCenterIndex;
TileInformation cellInformation = activeTilePlane[xIndex, yIndex];
// Initialize or clean the active tile cube cell
if (cellInformation == null)
{
cellInformation = new TileInformation(TileServerRequestCompleted);
activeTilePlane[xIndex, yIndex] = cellInformation;
}
else
{
cellInformation.Dispose();
}
// Calculate the center geo-coordinate for the current tile
Vector2 tileCenterPixelXY = centerPixelXY + tileDimensions * new Vector2(xDelta, yDelta);
GeoCoordinate tileCenterGeoCoordinate;
try
{
tileCenterGeoCoordinate = TileSystem.PixelXYToLatLong(tileCenterPixelXY, zoomLevel);
GetImageFromServer(cellInformation, tileCenterGeoCoordinate, zoomLevel, ViewType);
}
catch (ArgumentOutOfRangeException)
{
cellInformation.Image = unavailableImage;
}
}
}
}
/// <summary>
/// Sets the image from the image stream contained in the supplied asynchronous as the image for the tile
/// represented by the supplied tile information. The image stream will be closed.
/// </summary>
/// <param name="e">Asynchronous read result which contains the image stream and is free of errors.</param>
/// <param name="tileInformation">Tile information where the image is to be set.</param>
private void SetTileImage(OpenReadCompletedEventArgs e, TileInformation tileInformation)
{
// Read the image from the stream
Texture2D image = Texture2D.FromStream(SpriteBatch.GraphicsDevice, e.Result);
e.Result.Seek(0, SeekOrigin.Begin);
int imageByteCount = (int)e.Result.Length;
byte[] imageBuffer = tileInformation.AsyncImageBuffer;
// Resize the image buffer if it is too small
if (imageByteCount > imageBuffer.Length)
{
Array.Resize <byte>(ref imageBuffer, imageByteCount);
}
e.Result.Read(imageBuffer, 0, imageByteCount);
e.Result.Close();
tileInformation.Image = image;
}