Add cache strategy feature

Hello there 👋

It seems that it’s not possible to control how animations are cached by Lottie.

I’m using multiple Lottie animations in my app. All of them are cached in memory and take a lot a memory involving OutOfMemory errors. Currently, we can’t control which animation are cache in memory or disable this feature completely.

I’ve seen a lottie_cacheStrategy attribute in LottieAnimationView code but it doesn’t seem to exist anymore 😢 . Why has it been removed?

Here’s a sample of a memory dump showing the excessive amount of memory used by Lottie:

[timbru31]

Unfortunately, URLs are still being cached and PR #1450 did not fix this. Let me quickly outline the problem. When the cacheKey is null, the cache function of the LottieCompositionFactory recognized and honors this case: https://github.com/airbnb/lottie-android/blob/ee942249214dd6bb1540b746ca0b678a6382b5ee/lottie/src/main/java/com/airbnb/lottie/LottieCompositionFactory.java#L459-L474

Therefore a new network fetch is initiated, as it should be: https://github.com/airbnb/lottie-android/blob/ee942249214dd6bb1540b746ca0b678a6382b5ee/lottie/src/main/java/com/airbnb/lottie/LottieCompositionFactory.java#L80-L88

However, the NetworkFetcher looks in it’s cache and returns the cached file, i.e., the end user still sees the wrong animation. IMHO the NetworkFetcher needs to be adjusted to honor the no cache flag, too: https://github.com/airbnb/lottie-android/blob/master/lottie/src/main/java/com/airbnb/lottie/network/NetworkFetcher.java#L42

[messi-wpy]

there is no such things ,anyway i can’t find it . and lottie_cacheStrategy and cacheStrategy , it should have been removed. but in LottieCompositionFactory.fromUrl it still have LottieCompositionCache,however,it can’t control the size of local cache in appContext.getCacheDir()