[image-picker][ios] Fix Animated GIF support #20034
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Co-authored-by: Expo Bot <34669131+expo-bot@users.noreply.github.com>
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Co-authored-by: Tomasz Sapeta <tomasz.sapeta@swmansion.com>
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# Why I was talking to @hirbod who discovered that animated gifs aren't working on iOS in contrast to [what docs say](https://docs.expo.dev/versions/latest/sdk/imagepicker/#imagepickerlaunchimagelibraryasyncoptions): > Animated GIFs support If the selected image is an animated GIF, the result image will be an animated GIF too if and only if quality is set to undefined and allowsEditing is set to false. Otherwise compression and/or cropper will pick the first frame of the GIF and return it as the result (on Android the result will be a PNG, on iOS — GIF). What's more, I tracked it down that they probably never worked before (what I mentioned in #18138 description), because the initial Objective-C implementation was wrong (SDK 44 and earlier). Further Swift PRs (#15977, #18135, #18138) only refactored the already-bad Obj-C implementation. # How Found a way to do it properly with the `CoreGraphics` framework: - For non-compressed images, it is enough to passthrough the raw data - For images with `quality` set or being cropped, we need to recreate the GIF: 1. Get source image metadata 2. Create a destination buffer 3. Copy image frames, crop / compress each frame if needed 4. Save destination image data Also updated the docs accordingly. # Test Plan NCL on iOS Simulator, animated gif, all combinations of: - Quality: `undefined`, `1.0`, `!=1.0` - `allowsEditing`: `true`, `false` Also output from my test app (_the built-in iOS crop preview is buggy 🤷_): https://user-images.githubusercontent.com/278340/201655161-c09a8f2e-e51e-4ba3-bb5b-b953050d3f2c.mov # Discussion topics ❓ Two things: - It was undocumented, that on Android (at least SDK 47), quality MUST be set to `1.0` for animated gifs to work. Docs were saying something opposite, that it must be `undefined` (docs were wrong). My PR fixes that description. Please review my wording there. - On iOS, until now it wasn't working anyway. Even though I made it work for all qualities, it behaves the same for quality set to `1.0` or `undefined`. This is in contrast to JPEG, where quality defaults to `0.2`. Should we: 1. also compress the GIFs by default - when quality is not set, as we do for JPEG 2. keep them untouched as they're now on iOS - IMO this is better, because compression sometimes acts weirdly and they're larger than uncompressed If 1) then I need to adjust this PR to use default quality when `nil`. If 2) then the Android part needs a fix and so the docs accordingly. Co-authored-by: Expo Bot <34669131+expo-bot@users.noreply.github.com> Co-authored-by: Tomasz Sapeta <tomasz.sapeta@swmansion.com>
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Why
I was talking to @hirbod who discovered that animated gifs aren't working on iOS in contrast to what docs say:
What's more, I tracked it down that they probably never worked before (what I mentioned in #18138 description), because the initial Objective-C implementation was wrong (SDK 44 and earlier). Further Swift PRs (#15977, #18135, #18138) only refactored the already-bad Obj-C implementation.
How
Found a way to do it properly with the
CoreGraphicsframework:qualityset or being cropped, we need to recreate the GIF:Also updated the docs accordingly.
Test Plan
NCL on iOS Simulator, animated gif, all combinations of:
undefined,1.0,!=1.0allowsEditing:true,falseAlso output from my test app (the built-in iOS crop preview is buggy 🤷):
Screen.Recording.2022-11-14.at.13.00.23.mov
Discussion topics ❓
Two things:
It was undocumented, that on Android (at least SDK 47), quality MUST be set to
1.0for animated gifs to work. Docs were saying something opposite, that it must beundefined(docs were wrong). My PR fixes that description. Please review my wording there.On iOS, until now it wasn't working anyway. Even though I made it work for all qualities, it behaves the same for quality set to
1.0orundefined. This is in contrast to JPEG, where quality defaults to0.2. Should we:If 1) then I need to adjust this PR to use default quality when
nil.If 2) then the Android part needs a fix and so the docs accordingly.