/// <devdoc>
/// Removes an image from the image manager so it is no longer animated.
/// </devdoc>
public static void StopAnimate(Image image, EventHandler onFrameChangedHandler)
{
// Make sure we have a list of images
if (image == null || imageInfoList == null)
{
return;
}
// Acquire a writer lock to modify the image info list - See comments on Animate() about this locking.
bool readerLockHeld = rwImgListLock.IsReaderLockHeld;
LockCookie lockDowngradeCookie = new LockCookie();
threadWriterLockWaitCount++;
try {
if (readerLockHeld)
{
lockDowngradeCookie = rwImgListLock.UpgradeToWriterLock(Timeout.Infinite);
}
else
{
rwImgListLock.AcquireWriterLock(Timeout.Infinite);
}
}
finally {
threadWriterLockWaitCount--;
Debug.Assert(threadWriterLockWaitCount >= 0, "threadWriterLockWaitCount less than zero.");
}
try {
// Find the corresponding reference and remove it
for (int i = 0; i < imageInfoList.Count; i++)
{
ImageInfoExpender imageInfo = imageInfoList[i];
if (image == imageInfo.Image)
{
if ((onFrameChangedHandler == imageInfo.FrameChangedHandler) || (onFrameChangedHandler != null && onFrameChangedHandler.Equals(imageInfo.FrameChangedHandler)))
{
imageInfoList.Remove(imageInfo);
}
break;
}
}
}
finally {
if (readerLockHeld)
{
rwImgListLock.DowngradeFromWriterLock(ref lockDowngradeCookie);
}
else
{
rwImgListLock.ReleaseWriterLock();
}
}
}
static void AnimateImages50ms()
{
Debug.Assert(imageInfoList != null, "Null images list");
while (Dispose)
{
// Acquire reader-lock to access imageInfoList, elemens 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.
rwImgListLock.AcquireReaderLock(Timeout.Infinite);
try {
for (int i = 0; i < imageInfoList.Count; i++)
{
ImageInfoExpender imageInfo = imageInfoList[i];
imageInfo.FrameTimer += 5;
if (imageInfo.FrameTimer >= imageInfo.FrameDelay(imageInfo.Frame))
{
imageInfo.FrameTimer = 0;
if (imageInfo.Frame + 1 < imageInfo.FrameCount)
{
imageInfo.Frame++;
}
else
{
imageInfo.Frame = 0;
}
if (imageInfo.FrameDirty)
{
anyFrameDirty = true;
}
}
}
}
finally {
rwImgListLock.ReleaseReaderLock();
}
Thread.Sleep(50);
}
animationThread = null;
}
///// <devdoc>
///// Advances the frame in all images currently being animated. The new frame is drawn the next time the image is rendered.
///// </devdoc>
//public static void UpdateFrames() {
// if (!anyFrameDirty || imageInfoList == null) {
// return;
// }
// if (threadWriterLockWaitCount > 0) {
// // Cannot acquire reader lock at this time, frames update will be missed.
// return;
// }
// rwImgListLock.AcquireReaderLock(Timeout.Infinite);
// try {
// foreach (GifImageInfo imageInfo in imageInfoList) {
// // See comment in the class header about locking the image ref.
// lock (imageInfo.Image) {
// imageInfo.UpdateFrame();
// }
// }
// anyFrameDirty = false;
// }
// finally {
// rwImgListLock.ReleaseReaderLock();
// }
//}
/// <devdoc>
/// Adds an image to the image manager. If the image does not support animation this method does nothing.
/// This method creates the image list and spawns the animation thread the first time it is called.
/// </devdoc>
public static void Animate(Image image, EventHandler onFrameChangedHandler)
{
if (image == null)
{
return;
}
ImageInfoExpender imageInfo = null;
// 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 ImageInfoExpender(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.
bool readerLockHeld = rwImgListLock.IsReaderLockHeld;
LockCookie lockDowngradeCookie = new LockCookie();
threadWriterLockWaitCount++;
try {
if (readerLockHeld)
{
lockDowngradeCookie = rwImgListLock.UpgradeToWriterLock(Timeout.Infinite);
}
else
{
rwImgListLock.AcquireWriterLock(Timeout.Infinite);
}
}
finally {
threadWriterLockWaitCount--;
Debug.Assert(threadWriterLockWaitCount >= 0, "threadWriterLockWaitCount less than zero.");
}
try {
if (imageInfo.Animated)
{
// Construct the image array
//
if (imageInfoList == null)
{
imageInfoList = new List <ImageInfoExpender>();
}
// 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(new ThreadStart(AnimateImages50ms));
animationThread.Name = typeof(ImageAnimator).Name;
animationThread.IsBackground = true;
animationThread.Start();
}
}
}
finally {
if (readerLockHeld)
{
rwImgListLock.DowngradeFromWriterLock(ref lockDowngradeCookie);
}
else
{
rwImgListLock.ReleaseWriterLock();
}
}
}
