512217 - canvas arcTo() implementation is incorrect

Status: RESOLVED DUPLICATE of bug 471281

(Core :: Graphics: Canvas2D, defect)

Description

[Klaus Förster]

User-Agent:       Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2

According to the Canvas specification, the current implementation of arcTo(x1, y1, x2, y2, radius) in Firefox 3.5 is incorrect.

The specification states: "The method must connect the point (x0, y0) to the start tangent point by a straight line, adding the start tangent point to the subpath, and then must connect the start tangent point to the end tangent point by The Arc, adding the end tangent point to the subpath."

Given this text, the arc should end at the end tangent point t2 and not reach further to x2/y2.

SpecLink: http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-arcto

Reproducible: Always

Steps to Reproduce:
1. Open URL demonstrating the problem 
2. the right image shows correct rendering
3. the left image shows actual rendering
Actual Results:  
The arc in the left image ended at point x2/y2

Expected Results:  
The arc in the left image should end at point t2

Comment 1

[Justin Dolske [:Dolske]]

WFM on OS X trunk. Left and right are identical, line ends at t2.

Comment 2

[John P Baker]

Bug 471281 ?