Image.asset determines scale of asset based on whether path contains 3.0x

@tvolkert

Actual behavior: whenever a path to a file contains "3.0x" it will be displayed as a xxhdpi (3x) high resolution image
Expected behavior: must pay close attention to what the app developer specified in pubspec.yaml. Not doing so may compromise introducing other kinds of variants in the future.

Sample pubspec.yaml

. . .
  assets:
    - assets/3.0x/ic_accessibility_black_36dp.png 
    - assets/3.0x/yetAnotherFolder/hackyAsset.png

When loading such images with

new Image.asset('assets/3.0x/yetAnotherFolder/hackyAsset.png'),

or

 new Image.asset('assets/3.0x/ic_accessibility_black_36dp.png'),

expected behavior: They should behave like mdpi (1x) images
actual behavior: They behave like xxhdpi (3x) hi-res image

There are 2 pitfalls here. The obvious one is that path assets/3.0x/yetAnotherFolder doesn't comply with the specs that the main file sits on <folder> and the variant sits on <folder>/3.0x. The second is that the intention of the app developer may have been putting a mdpi (1x) file on assets/3.0x/ic_accessibility_black_36dp.png .

I like how smart it is, but a) this is clashing with what AssetManifest.json says. And b) I'm afraid that one day other types of variants (say screen size, localization...) will make pre-existing apps break because they'll start treating its main variant assets as non-main variants. In any case I can't be sure if this is a feature or a bug. I'd like to help document it properly if it's the former or fix it if it's the latter.

@tvolkert @Hixie @HansMuller

Inspecting pubspec.yaml for flutter gallery I got a bit more confused:

flutter:
  uses-material-design: true
  assets:
    - lib/gallery/example_code.dart
    - packages/flutter_gallery_assets/white_logo/logo.png
    - packages/flutter_gallery_assets/white_logo/1.5x/logo.png
    - packages/flutter_gallery_assets/white_logo/2.5x/logo.png
    - packages/flutter_gallery_assets/white_logo/3.0x/logo.png
    - packages/flutter_gallery_assets/white_logo/4.0x/logo.png
    - packages/flutter_gallery_assets/videos/butterfly.mp4
    - packages/flutter_gallery_assets/animated_flutter_lgtm.gif
. . .

I would expect this

flutter:
  uses-material-design: true
  assets:
    - lib/gallery/example_code.dart
    - packages/flutter_gallery_assets/white_logo/logo.png
    - packages/flutter_gallery_assets/videos/butterfly.mp4
    - packages/flutter_gallery_assets/animated_flutter_lgtm.gif
. . .

@HansMuller

Yeah me too. @HansMuller do the variants need to be explicitly listed?

I'm terribly bad at regular expressions or else I'd already have changed it in image_resolution.dart. Anyway, the new unit tests included in above commit should be a good conversation started to get everybody on the same page on this problem.

Also removed puzzling lines from gallery's pubspec, I built app and it's still working.

@fmatosqg

@fmatosqg you are correct about the white_logo gallery asset variants. Sorry about that, my fault.

@HansMuller

@HansMuller as long as we're in the business of problem solving (not blame assigning) that's just a hiccup :)

I'm still not confident I understand all the intentions behind asset image ratios but I tried to enforce my own understanding of it with unit tests and a small fix on #17322. I'd suggest reading the comments before the code, I hope the clarification is clear enough (no pun intended)

Make image resolution more strict, clean gallery pubspec.yaml (flutte…

Code review - write more tests and revert to previous public api (flu…

Make image resolution more strict, clean gallery pubspec.yaml (#17241) (

It looks like this was closed by #17322 - feel free to re-open if there's more to do here.

That's right, #17322 completely covers this issue.

cafa097 Revert "Roll src/third_party/dart ba8baa46b452..fbd0c8a46813 …

flutter-team-archive/engine@2d42c74...d7ad50c

cafa097 Revert "Roll src/third_party/dart ba8baa46b452..fbd0c8a46813 …

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

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Image.asset determines scale of asset based on whether path contains 3.0x #17241

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Image.asset determines scale of asset based on whether path contains 3.0x #17241

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fmatosqg commented on May 3, 2018

tvolkert commented on May 3, 2018

fmatosqg commented on May 4, 2018

HansMuller commented on May 4, 2018

fmatosqg commented on May 5, 2018

tvolkert commented on May 29, 2018

fmatosqg commented on May 29, 2018

github-actions commented on Sep 3, 2021

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