/// <summary>
/// Checks the existence of the identified asset as an async method.
/// </summary>
/// <param name="id">The asset identifier.</param>
/// <returns>Implementors should return true if a stream can be created.</returns>
protected override async Task <bool> CheckExistsAsync(string id)
{
return(await Task.Factory.StartNew(() =>
{
if (id == null)
{
throw new ArgumentNullException(nameof(id));
}
// If it is an absolute path (e.g. C:\SomeDir\AnAssetFile.ext) directly check its presence
if (Path.IsPathRooted(id))
{
return File.Exists(id);
}
// Path seems relative. First see if the file exists at the current working directory
if (File.Exists(id))
{
return true;
}
foreach (var baseDir in _baseDirs)
{
string path = Path.Combine(baseDir, id);
if (File.Exists(path))
{
return true;
}
}
return false;
}));
}
/// <summary>
/// Create an async stream for the asset identified by id.
/// </summary>
/// <param name="id">The asset identifier.</param>
/// <returns>Implementors should return null if the asset cannot be retrieved. Otherwise returns a file stream to the asset.</returns>
protected override async Task <Stream> GetStreamAsync(string id)
{
return(await Task <Stream> .Factory.StartNew(() =>
{
if (id == null)
{
throw new ArgumentNullException(nameof(id));
}
// If it is an absolute path (e.g. C:\SomeDir\AnAssetFile.ext) open it directly
if (Path.IsPathRooted(id))
{
return new FileStream(id, FileMode.Open);
}
// Path seems relative. First see if the file exists at the current working directory
if (File.Exists(id))
{
return new FileStream(id, FileMode.Open);
}
// At last, look at the specified base directories
foreach (var baseDir in _baseDirs)
{
string path = Path.Combine(baseDir, id);
if (File.Exists(path))
{
return new FileStream(path, FileMode.Open);
}
}
return null;
}));
}