- From: <bugzilla@jessica.w3.org>
- Date: Tue, 15 Feb 2011 17:57:33 +0000
- To: public-html@w3.org
http://www.w3.org/Bugs/Public/show_bug.cgi?id=12089
Summary: Under 4.8.11.1.2, Transformations, the specification
reads: The transformations must be performed in
reverse order. For instance, if a scale transformation
that doubles the width is applied, followed by a
rotation transformation that rotates drawing opera
Product: HTML WG
Version: unspecified
Platform: Other
URL: http://www.whatwg.org/specs/web-apps/current-work/#tra
nsformations
OS/Version: other
Status: NEW
Severity: normal
Priority: P3
Component: HTML Canvas 2D Context (editor: Ian Hickson)
AssignedTo: ian@hixie.ch
ReportedBy: contributor@whatwg.org
QAContact: public-html-bugzilla@w3.org
CC: mike@w3.org, public-html-wg-issue-tracking@w3.org,
public-html@w3.org
Specification:
http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html
Section:
http://www.whatwg.org/specs/web-apps/current-work/complete.html#transformations
Comment:
Under 4.8.11.1.2, Transformations, the specification reads: The
transformations must be performed in reverse order. For instance, if a scale
transformation that doubles the width is applied, followed by a rotation
transformation that rotates drawing operations by a quarter turn, and a
rectangle twice as wide as it is tall is then drawn on the canvas, the actual
result will be a square. ... This is incorrect. Rotation and scaling are
commutative. When a rectangle is rotated a quarter turn by changing the
coordinate space, the x-axis is vertical, and scaling up the x direction will
not compress the rectangle into a square. Instead, it will make it 4x as tall
as it is wide, just as it does if you scale first, then rotate.
Posted from: 67.116.239.5
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Received on Tuesday, 15 February 2011 17:57:35 UTC