internal static void EnsureSave(GifImage image, string filename, Stream dataStream)
{
if (!image.RawGuid.Equals(GifGuid))
{
return;
}
var animatedGif = false;
var dimensions = image.FrameDimensionsList;
if (dimensions.Select(guid => new GifFrameDimension(guid)).Contains(GifFrameDimension.Time))
{
animatedGif = image.GetFrameCount(GifFrameDimension.Time) > 1;
}
if (!animatedGif)
{
return;
}
try
{
Stream created = null;
long lastPos = 0;
if (dataStream != null)
{
lastPos = dataStream.Position;
dataStream.Position = 0;
}
try
{
if (dataStream == null)
{
created = dataStream = File.OpenRead(filename);
}
image._rawData = new byte[(int)dataStream.Length];
dataStream.Read(image._rawData, 0, (int)dataStream.Length);
}
finally
{
if (created != null)
{
created.Close();
}
else
{
// ReSharper disable once PossibleNullReferenceException
dataStream.Position = lastPos;
}
}
}
// possible exceptions for reading the filename
catch (UnauthorizedAccessException)
{
}
catch (DirectoryNotFoundException)
{
}
catch (IOException)
{
}
// possible exceptions for setting/getting the position inside dataStream
catch (NotSupportedException)
{
}
catch (ObjectDisposedException)
{
}
// possible exception when reading stuff into dataStream
catch (ArgumentException)
{
}
}
public static void Animate(GifImage image, EventHandler onFrameChangedHandler)
{
if (image == null)
{
return;
}
GifImageInfo imageInfo;
// See comment in the class header about locking the image ref.
lock (image)
{
// could we avoid creating an ImageInfo object if FrameCount == 1 ?
imageInfo = new GifImageInfo(image);
}
// If the image is already animating, stop animating it
StopAnimate(image, onFrameChangedHandler);
// Acquire a writer lock to modify the image info list. If the thread has a reader lock we need to upgrade
// it to a writer lock; acquiring a reader lock in this case would block the thread on itself.
// If the thread already has a writer lock its ref count will be incremented w/o placing the request in the
// writer queue. See ReaderWriterLock.AcquireWriterLock method in the MSDN.
var readerLockHeld = RwImgListLock.IsReaderLockHeld;
var lockDowngradeCookie = new LockCookie();
ThreadWriterLockWaitCount++;
try
{
if (readerLockHeld)
{
lockDowngradeCookie = RwImgListLock.UpgradeToWriterLock(Timeout.Infinite);
}
else
{
RwImgListLock.AcquireWriterLock(Timeout.Infinite);
}
}
finally
{
ThreadWriterLockWaitCount--;
}
try
{
if (imageInfo.Animated)
{
// Construct the image array
//
if (ImageInfoList == null)
{
ImageInfoList = new List <GifImageInfo>();
}
// Add the new image
//
imageInfo.FrameChangedHandler = onFrameChangedHandler;
ImageInfoList.Add(imageInfo);
// Construct a new timer thread if we haven't already
//
if (AnimationThread == null)
{
AnimationThread = new Thread(AnimateImages50Ms)
{
Name = typeof(ImageAnimator).Name,
IsBackground = true
};
AnimationThread.Start();
}
}
}
finally
{
if (readerLockHeld)
{
RwImgListLock.DowngradeFromWriterLock(ref lockDowngradeCookie);
}
else
{
RwImgListLock.ReleaseWriterLock();
}
}
}
