/// <summary>
/// Worker thread procedure which implements the main animation loop.
/// NOTE: This is the ONLY code the worker thread executes, keeping it in one method helps better understand
/// any synchronization issues.
/// WARNING: Also, this is the only place where ImageInfo objects (not the contained image object) are modified,
/// so no access synchronization is required to modify them.
/// </summary>
private static void AnimateImages()
{
Debug.Assert(s_imageInfoList != null, "Null images list");
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
while (true)
{
Thread.Sleep(40);
// Because Thread.Sleep is not accurate, capture how much time has actually elapsed during the animation
long timeElapsed = stopwatch.ElapsedMilliseconds;
stopwatch.Restart();
// Acquire reader-lock to access imageInfoList, elements in the list can be modified w/o needing a writer-lock.
// Observe that we don't need to check if the thread is waiting or a writer lock here since the thread this
// method runs in never acquires a writer lock.
s_rwImgListLock.AcquireReaderLock(Timeout.Infinite);
try
{
for (int i = 0; i < s_imageInfoList.Count; i++)
{
ImageInfo imageInfo = s_imageInfoList[i];
if (imageInfo.Animated)
{
imageInfo.AdvanceAnimationBy(timeElapsed);
if (imageInfo.FrameDirty)
{
s_anyFrameDirty = true;
}
}
}
}
finally
{
s_rwImgListLock.ReleaseReaderLock();
}
}
}