Add command line argument to disable alpha removal

[fastlanebot]

Original issue by @vytis - Imported from fastlane/snapshot#20

It is a convenient feature when generating screenshots for app submission, but it is not needed when creating them for UI testing. At the moment I am always Ctrl+C'ing after the last screenshot is made...

[fastlanebot]

@KrauseFx commented

Does this take so long? It's just 10 seconds for ~50 screenshots maybe. Recently I changed it so the alpha gets removed after each set of screenshots (simulator change, language change)

Does this still bug you. I think adding a flag or option just to save some seconds on your continuous integration machine or your local computer might not be worth the trouble.

What are your thoughts?

[fastlanebot]

@vytis commented

Just checked on my setup - 1st gen retina MBP. One device (iPad) with 16 screenshots takes 12 seconds. At the moment our app supports 13 languages and 5 different devices (all iPhones + iPad). The screenshots dir is about 750mb... Didn't wait for it to finish, but I presume it will take quite some time.

I guess the main reason I'm thinking about these issues is because I'm using snapshot for UI testing, not for generating screenshots for iTunes Connect. I want to run the test suite as often as possible and any time shaved from it is very useful.

[fastlanebot]

@KrauseFx commented

Makes sense.

[fastlanebot]

@KrauseFx commented

Here we go: fastlane-old/snapshot@cae96a2

Just add skip_alpha_removal to your Snapfile

Let me know if that works as expected.

[fastlanebot]

@vytis commented

Yes works perfect!