Image validation

[roryqueue]

NOT READ TO MERGE but progress on #289 ... there doesn't seem to be a great package out there to get height and width etc. for png, gif, and jpeg images without bringing in a big dependency e.g. ImageMagick, so I wrote a lot of it by hand after reading through the code of several packages on Awesome-Elixir. Still needs test coverage, parameter tweaking, error handling, and edge case coverage, but let me know if I'm off track and any steering is needed.

[joshsmith]

Any idea what the performance implications are here?

[roryqueue]

Not really, but that's something I can test.

[joshsmith]

You can use benchfella.

[roryqueue]

sounds good, will do, thanks for the tip!

[roryqueue]

Apologies for the delay, I've been traveling in Morocco and the rocky internet situation I had made it tough to progress. Really feel for those devs in countries with weak infrastructure. Anyways, here are the results:

## ImageBench
benchmark name         iterations   average time
get_gif_still_stats         50000   55.53 µs/op
get_png_normal_stats        20000   84.29 µs/op
get_gif_moving_stats        20000   101.25 µs/op
get_jpeg_normal_stats        5000   359.24 µs/op
get_png_large_stats          5000   378.44 µs/op
get_jpeg_large_stats         1000   2445.87 µs/op

In summary, I'd somewhat unscientifically say it should add single digit milliseconds to a POST in a ~99th percentile scenario.

Work here: https://github.com/roryqueue/code-corps-image-bench . Please let me know if you see a flaw in this measurement methodology. I basically just copied over the incremental code that will run but I certainly may have missed something.

[joshsmith]

@roryqueue looks really good!

We'll also want to consider bringing this in ASAP and working through how, precisely, to do it for Ember:

stavro/arc#125
https://github.com/stavro/arc/wiki/Direct-to-S3-Uploads

[roryqueue]

Gotcha, yeah that sounds good to me. Been digging through the linked for a bit. Am I off track to think we would actually want to use something like this: https://github.com/benefitcloud/ember-uploader#uploading-to-s3 to upload the image, translating the code in this PR to the Ember app in its entirety, and then just send the s3 image path to the Phoenix app?

[roryqueue]

Oh we'd probably have to sign the upload with a request to Phoenix before the Ember -> S3 step as well, right?

[joshsmith]

@roryqueue sorry I fell off the wagon on this one. I'm not quite positive, to be honest. Would love some deeper research into it to know for sure.

[roryqueue]

On vaca now with limited computer access, but I can look into this next week if needed!

[joshsmith]

@roryqueue absolutely! Enjoy the vacation.

[joshsmith]

Closing this because we switched to Cloudinary from using arc and arc_ecto altogether. Thanks for work @roryqueue and sorry for having to close.