CGColor - Determining the blended color from two UIViews that are on top of each other

Question

I am trying to obtain the resultant CGColor (or UIColor) that would be displayed as a result of two (or perhaps more) views that are sat on top of each other each with differing colours. Obviously the view(s) nearer the foreground have an alpha value of less than 1, allowing the colour of views behind to bleed through.

Essentially, I guess I'm trying to mimic exactly what the UIView compositing process does exactly when it prepares for the painting of a scene.

NB. I'd like to steer away from a manual programmatic blend algorithm as will likely not be the same as the Cocoa blend mechanism.

I have just found this... Can I mix two UIColor together? but thought there must be an iOS/Cocoa equivalent

Indeed it is. Happy with help in CGColor world if that makes it easier — GrowlingBadger, Mar 27 '15 at 07:58
I cobbled together some stuff that should help you resolve it and put it in an answer. Hope it helps. — clearlight, Mar 27 '15 at 08:12

score 1 · Accepted Answer · edited May 23 '17 at 10:24

1

Heres a tutorial-ish thing:

Blending Modes in iOS

And here is the Apple Documentation that covers blend modes. Should get you on the right track. The exact formulas are shown for each blend mode option.

Finally, see this answer:

How to get the color of a displayed pixel

edited May 23 '17 at 10:24

Community

1
1

answered Mar 27 '15 at 08:04

clearlight

12,255
11
57
75

CGColor - Determining the blended color from two UIViews that are on top of each other

1 Answers1