This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.

Bug 11397 - Additional compositing operations such as 'max-alpha' and 'min-alpha' would make it much easier to make soft brush and eraser tools in painting applications.
Summary: Additional compositing operations such as 'max-alpha' and 'min-alpha' would m...
Status: RESOLVED NEEDSINFO
Alias: None
Product: HTML WG
Classification: Unclassified
Component: LC1 HTML Canvas 2D Context (show other bugs)
Version: unspecified
Hardware: All All
: P3 enhancement
Target Milestone: ---
Assignee: Ian 'Hixie' Hickson
QA Contact: HTML WG Bugzilla archive list
URL: http://www.whatwg.org/specs/web-apps/...
Whiteboard: canvas RFE
Keywords:
Depends on:
Blocks:
 
Reported: 2010-11-24 17:08 UTC by contributor
Modified: 2012-02-29 22:41 UTC (History)
6 users (show)

See Also:

Attachments

Description contributor 2010-11-24 17:08:28 UTC 
Specification: http://www.whatwg.org/specs/web-apps/current-work/
Section: http://www.whatwg.org/specs/web-apps/current-work/complete.html#compositing

Comment:
Additional compositing operations such as 'max-alpha' and 'min-alpha' would
make it much easier to make soft brush and eraser tools in painting
applications.

Posted from: 87.114.199.5
Comment 1 L. David Baron (Mozilla) 2010-11-24 20:32:26 UTC 
Do you have documentation for (a) how they work and (b) whether major 2D graphics systems support them?
Comment 2 Richard Poole 2010-11-25 16:19:54 UTC 
I couldn't find any graphics library support for 'max-alpha' or 'min-alpha' unfortunately, but Cairo and Qt do support a broader set of compositing modes:

- http://cairographics.org/manual/cairo-cairo-t.html#cairo-operator-t
- http://doc.qt.nokia.com/4.7/qpainter.html#CompositionMode-enum
Comment 3 Ian 'Hixie' Hickson 2011-01-10 22:12:09 UTC 
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the tracker issue; or you may create a tracker issue yourself, if you are able to do so. For more details, see this document:
   http://dev.w3.org/html5/decision-policy/decision-policy.html

Status: Partially Accepted
Change Description: none yet
Rationale: This seems reasonable, if we could get definitions of the new composition operators, but we should probably wait until we have the existing composition operators defined and implemented consistently before adding more!
Comment 4 Michael[tm] Smith 2011-08-04 05:03:31 UTC 
mass-move component to LC1
Comment 5 Ian 'Hixie' Hickson 2012-02-29 20:43:55 UTC 
To add this, we need a precise description of what the operators are.

See also bug 9307.
Comment 6 Ian 'Hixie' Hickson 2012-02-29 22:41:13 UTC 
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the tracker issue; or you may create a tracker issue yourself, if you are able to do so. For more details, see this document:
   http://dev.w3.org/html5/decision-policy/decision-policy.html

Status: Did Not Understand Request
Change Description: no spec change
Rationale: see comment 5