Acrylic brushes change the values I provide

When using an acrylic brush, there is math applied to the color value, tint value, and luminosity value that change these values to make the acrylic work more like rs4 acrylic - this conversion changes our desired results, and means designers literally cannot achieve their designs - the values they hand off to code do not get reproduced by the brush. not only that, because there are value caps in place, certain values are not achievable at all.

This conversion logic is not desired by designers, and is almost entirely unknown so it cannot be worked around by many. This needs to be an option to opt in or opt out option, or a new version produced that does not have this conversion built in so expected results can be achieved.

The conversion is not documented, and is currently ignored by MS! Lets fix this to make design achievable and the brush simpler!

Bug Report

Describe the bug

There is “auto-magic” logic built into the current Acrylic brush (that was put in place to replicate the RS4 acrylic visual appearance at the time), that now conflicts with the contrast ratios needed in order to pass WCAG 2.1 accessibility requirements.

This logic affects the color of the luminosity blend mode and the tint color properties and sets them automatically based on the tint color of the brush.

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Attempt to set the TintLuminosityOpacity to below #202020 and observe that it will lock at that value instead, regardless of what you put it’s hex color value to.

Expected behavior

If TintLuminosityOpacity property is set, then all automatic RS4 logic will be be ignored, and the values specified by the user will be set in the brush 1:1.

Screenshots

Version Info

NuGet package version:

Windows 10 version	Saw the problem?
Insider Build (xxxxx)	19493
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	yes
Mobile	yes
Xbox	yes
Surface Hub	yes
IoT	yes

[kikisaints]

@chingucoding that looks correct to me. That you for summarizing.

[chingucoding]

Yes the only case where we want to change stuff is when luminosity opacity is actively set.

Yes this whole maths is a bit complicated. So summary:

The Luminosity layer should behave the following:

• Luminosity not specified: Leave as is
• Luminosity specified: Use tint color, tint opacity and luminosity opacity all unmodified

The other layers are already correct as they are. Is this correct @SpencerHurd and @kikisaints ?