Image get from cache only

[rmarau]

New feature: Adds the possibility to show the image only if it is cached - skips the network download.

Bug fix: When an image is not valid (the codec fails), the errorWidget was not replacing the placeholder.

Also Fixes a deprecation warning from dart2.

[JohannesKaufmann]

@renefloor I think that this is a neat feature. My use case would be:

• user is on mobile data
• show the high resolution image if it is in the cache
• if it's not found show a low resolution image

That way the user can enjoy a high resolution image while on wifi & does not download a high resolution image while away from home.

The most simple solution for me would be to switch urls based on the connectivity but that would mean that while away from home all images would be downloaded again in low resolution even if the high resolution images are still in the cache.

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Another option would be a function (for example bool isCached(String url)) that exposes wether the image was found in the cache.

[Daaaab]

Was about to post this feature, yet I've found this. It would be very useful since I'm using Firebase storage, as my backend, and I don't want to download all images every single time, to stay in my transfer limits.