Modified transparency to go through a range of values instead of being an on/off switch

[carlo-ev]

'made _transparent a decimal so that opacity can be a decreasing range from 1 to options.opacity'

Fixes #311

I changed the _transparent from boolean to a decimal, the idea is that the opacity start at 1 and each click on the toolbar reduces the value by 0.1 until it the value of this.options.opacity, when it does the opacity is reset back to 1.

@sashadev-sky
Please let me know if this isn't the functionality of this feature to change it up.
Thanks.

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[jywarren]

Oh, this is very cool! Would you be able to share a gif of this working? Thank you!!!

[jywarren]

Hopefully after we get #680 working, we can rebase this and test it out live in GitPod!

[carlo-ev]

Sorry for the late response, right now the opacity starts in 1 and does -0.1 every click until it hits options.opacity and then goes back around.

[sashadev-sky]

This is great thank you! Sorry for the late review. You have the basic idea, the only issue here is what to do about the toolbar icon. It used to toggle between 2 icons depending on this._transparent. We need to add some sort of way to deal with the icon and make it dynamic to show interactivity - and also so the user can see what the current opacity state of the image is