//TODO (CR Sept 2010): same comment as with the ProgressGraphic stuff; the API is unclear
//as to what it is doing (return value) because it's trying to account for the async loading.
/// <summary>
/// Attempts to start loading the overlay data asynchronously, if not already loaded.
/// </summary>
/// <param name="progress">A value between 0 and 1 indicating the progress of the asynchronous loading operation.</param>
/// <param name="message">A string message detailing the progress of the asynchronous loading operation.</param>
/// <returns></returns>
public bool BeginLoad(out float progress, out string message)
{
// update the last access time
_largeObjectData.UpdateLastAccessTime();
// if the data is already available without blocking, return success immediately
//TODO (CR Sept 2010): because unloading the volume involves disposing it, if every operation that uses it
//isn't in the same lock (e.g. lock(_syncVolumeDataLock)) you could be getting a disposed/null volume here.
VolumeData volume = _volume;
if (volume != null)
{
message = SR.MessageFusionComplete;
progress = 1f;
return(true);
}
lock (_syncLoaderLock)
{
message = SR.MessageFusionInProgress;
progress = 0;
if (_volumeLoaderTask == null)
{
// if the data is available now, return success
volume = _volume;
if (volume != null)
{
message = SR.MessageFusionComplete;
progress = 1f;
return(true);
}
_volumeLoaderTask = new BackgroundTask(c => this.LoadVolume(c), false, null)
{
ThreadUICulture = Application.CurrentUICulture
};
_volumeLoaderTask.Run();
_volumeLoaderTask.Terminated += OnVolumeLoaderTaskTerminated;
}
else
{
if (_volumeLoaderTask.LastBackgroundTaskProgress != null)
{
message = _volumeLoaderTask.LastBackgroundTaskProgress.Progress.Message;
progress = _volumeLoaderTask.LastBackgroundTaskProgress.Progress.Percent / 100f;
}
}
}
return(false);
}
private void UnloadVolume()
{
// wait for synchronized access
lock (_syncVolumeDataLock)
{
// dump our data
if (_volume != null)
{
_volume.Dispose();
_volume = null;
}
// update our stats
_largeObjectData.BytesHeldCount = 0;
_largeObjectData.LargeObjectCount = 0;
// unregister with memory manager
MemoryManager.Remove(this);
}
this.OnUnloaded();
}
private VolumeData LoadVolume(IBackgroundTaskContext context)
{
// wait for synchronized access
lock (_syncVolumeDataLock)
{
// if the data is now available, return it immediately
// (i.e. we were blocked because we were already reading the data)
if (_volume != null)
{
return(_volume);
}
// load the volume data
if (context == null)
{
_volume = VolumeData.Create(_frames);
}
else
{
_volume = VolumeData.Create(_frames, (n, count) => context.ReportProgress(new BackgroundTaskProgress(n, count, SR.MessageFusionInProgress)));
}
// update our stats
_largeObjectData.BytesHeldCount = 2 * _volume.SizeInVoxels;
_largeObjectData.LargeObjectCount = 1;
_largeObjectData.UpdateLastAccessTime();
// regenerating the volume data is easy when the source frames are already in memory!
_largeObjectData.RegenerationCost = RegenerationCost.Low;
// register with memory manager
MemoryManager.Add(this);
return(_volume);
}
}
