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WebP with alpha on API 17

See original GitHub issue

I’m using compile 'com.facebook.fresco:webpsupport:0.10.0' to support transparent webp images on devices < 18 API (API 18 is when native support was added to framework).

But on some devices on API 17 (for example Huawei Ascend G700) I’m facing this weird bug: screenshot (for the reference, it should look like this). These webp images are from official google samples (WebP-lossy with alpha).

Is there some workaround about this?

Issue Analytics

State:
Created 7 years ago
Comments:6 (4 by maintainers)

Top GitHub Comments

1reaction

pavlo-zincommented, Jun 10, 2016

@massimocarli I reckon the problem is with decoding, as I’m getting the same bug with setWebpSupportEnabled(false).

0reactions

zjupurecommented, Jan 1, 2018

@massimocarli I have met this problem too. On some API <=17 devices, webp with alpha cannot be decoded normally. After some investigation, I found fresco use the wrong colorspace to decode webp in webp_bitmapfactory.cpp . The colorspace should be MODE_rgbA not MODE_RGBA, because in Android system, Bitmap pixel array are pre-multiplied by default. You can see in webp.cpp which account for decoding animated webp images, MODE_rgbA is using there, so webp frames with alpha can be displayed correctly.

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