Bug 140646 - Support "plus-darker" in mix-blend mode
Summary: Support "plus-darker" in mix-blend mode
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: CSS (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Dean Jackson
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2015-01-19 16:33 PST by Dean Jackson
Modified: 2015-01-20 08:04 PST (History)
0 users

See Also:

Attachments
Patch (1.18 MB, patch)
2015-01-19 17:45 PST, Dean Jackson 		simon.fraser: review+
Details | Formatted Diff | Diff
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Description Dean Jackson 2015-01-19 16:33:00 PST 
Support for "plus-darker" in mix-blend-mode. Here is the email I sent to public-fx.

https://lists.w3.org/Archives/Public/public-fx/2015JanMar/0021.html

Our designers at Apple often request a blending operation that is not supported in the CSS Compositing and Blending specification: plus-darker. You can find many examples and discussion of this mode if you Bing on the Google.

We’d like to add this mode to Level 2.

Details are here: http://en.wikipedia.org/wiki/Blend_modes#Addition

The math is pretty simple:

R = min(0, (1 - D) + (1 - S))

(We should maybe consider adding plus-lighter as well, and subtractive modes based on designer feedback)
Comment 1 Dean Jackson 2015-01-19 16:33:12 PST 
rdar://problem/19523370
Comment 2 Dean Jackson 2015-01-19 17:45:27 PST 
Created attachment 244946 [details]
Patch
Comment 3 Dean Jackson 2015-01-20 08:04:06 PST 
Committed r178710: <http://trac.webkit.org/changeset/178710>