// Returns the task if we started the task or the task is already started.
private Future<?> startTaskIfNeeded(int index, int which) {
if (index < mActiveStart || index >= mActiveEnd) return null;
ImageEntry entry = mImageCache.get(getVersion(index));
if (entry == null) return null;
if (which == BIT_SCREEN_NAIL && entry.screenNailTask != null) {
return entry.screenNailTask;
} else if (which == BIT_FULL_IMAGE && entry.fullImageTask != null) {
return entry.fullImageTask;
}
MediaItem item = mData[index % DATA_CACHE_SIZE];
Utils.assertTrue(item != null);
if (which == BIT_SCREEN_NAIL && (entry.requestedBits & BIT_SCREEN_NAIL) == 0) {
entry.requestedBits |= BIT_SCREEN_NAIL;
entry.screenNailTask =
mThreadPool.submit(
new ScreenNailJob(item), new ScreenNailListener(item.getDataVersion()));
// request screen nail
return entry.screenNailTask;
}
if (which == BIT_FULL_IMAGE
&& (entry.requestedBits & BIT_FULL_IMAGE) == 0
&& (item.getSupportedOperations() & MediaItem.SUPPORT_FULL_IMAGE) != 0) {
entry.requestedBits |= BIT_FULL_IMAGE;
entry.fullImageTask =
mThreadPool.submit(
item.requestLargeImage(), new FullImageListener(item.getDataVersion()));
// request full image
return entry.fullImageTask;
}
return null;
}
private void updateImageRequests() {
if (!mIsActive) return;
int currentIndex = mCurrentIndex;
MediaItem item = mData[currentIndex % DATA_CACHE_SIZE];
if (item == null || item.getPath() != mItemPath) {
// current item mismatch - don't request image
return;
}
// 1. Find the most wanted request and start it (if not already started).
Future<?> task = null;
for (int i = 0; i < sImageFetchSeq.length; i++) {
int offset = sImageFetchSeq[i].indexOffset;
int bit = sImageFetchSeq[i].imageBit;
task = startTaskIfNeeded(currentIndex + offset, bit);
if (task != null) break;
}
// 2. Cancel everything else.
for (ImageEntry entry : mImageCache.values()) {
if (entry.screenNailTask != null && entry.screenNailTask != task) {
entry.screenNailTask.cancel();
entry.screenNailTask = null;
entry.requestedBits &= ~BIT_SCREEN_NAIL;
}
if (entry.fullImageTask != null && entry.fullImageTask != task) {
entry.fullImageTask.cancel();
entry.fullImageTask = null;
entry.requestedBits &= ~BIT_FULL_IMAGE;
}
}
}
private void updateImageCache() {
HashSet<Long> toBeRemoved = new HashSet<Long>(mImageCache.keySet());
for (int i = mActiveStart; i < mActiveEnd; ++i) {
MediaItem item = mData[i % DATA_CACHE_SIZE];
long version = item == null ? MediaObject.INVALID_DATA_VERSION : item.getDataVersion();
if (version == MediaObject.INVALID_DATA_VERSION) continue;
ImageEntry entry = mImageCache.get(version);
toBeRemoved.remove(version);
if (entry != null) {
if (Math.abs(i - mCurrentIndex) > 1) {
if (entry.fullImageTask != null) {
entry.fullImageTask.cancel();
entry.fullImageTask = null;
}
entry.fullImage = null;
entry.requestedBits &= ~BIT_FULL_IMAGE;
}
} else {
entry = new ImageEntry();
entry.rotation = item.getFullImageRotation();
mImageCache.put(version, entry);
}
}
// Clear the data and requests for ImageEntries outside the new window.
for (Long version : toBeRemoved) {
ImageEntry entry = mImageCache.remove(version);
if (entry.fullImageTask != null) entry.fullImageTask.cancel();
if (entry.screenNailTask != null) entry.screenNailTask.cancel();
}
}