private static bool GetCachedImage(string cacheKey, out ImageSource image)
{
image = null;
var buffer = Cache.Get(cacheKey) as byte[];
if (buffer != null)
{
try
{
using (var memoryStream = new MemoryStream(buffer))
{
image = ImageLoader.FromStream(memoryStream);
}
DateTime expiration = DateTime.MinValue;
if (buffer.Length >= 16 && Encoding.ASCII.GetString(buffer, buffer.Length - 16, 8) == "EXPIRES:")
{
expiration = new DateTime(BitConverter.ToInt64(buffer, buffer.Length - 8), DateTimeKind.Utc);
}
return(expiration > DateTime.UtcNow);
}
catch (Exception ex)
{
Debug.WriteLine("{0}: {1}", cacheKey, ex.Message);
}
}
return(false);
}
private static ImageSource DownloadImage(Uri uri, string cacheKey)
{
ImageSource image = null;
try
{
var request = WebRequest.CreateHttp(uri);
if (HttpUserAgent != null)
{
request.UserAgent = HttpUserAgent;
}
using (var response = (HttpWebResponse)request.GetResponse())
{
if (response.Headers["X-VE-Tile-Info"] != "no-tile") // set by Bing Maps
{
using (var responseStream = response.GetResponseStream())
using (var memoryStream = new MemoryStream())
{
responseStream.CopyTo(memoryStream);
memoryStream.Seek(0, SeekOrigin.Begin);
image = ImageLoader.FromStream(memoryStream);
if (cacheKey != null)
{
SetCachedImage(cacheKey, memoryStream, GetExpiration(response.Headers));
}
}
}
}
}
catch (WebException ex)
{
Debug.WriteLine("{0}: {1}: {2}", uri, ex.Status, ex.Message);
}
catch (Exception ex)
{
Debug.WriteLine("{0}: {1}", uri, ex.Message);
}
return(image);
}
private static ImageSource LoadImage(string path)
{
ImageSource image = null;
if (File.Exists(path))
{
try
{
using (var fileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
{
image = ImageLoader.FromStream(fileStream);
}
}
catch (Exception ex)
{
Debug.WriteLine("{0}: {1}", path, ex.Message);
}
}
return(image);
}
