9740 2010-05-15 10:16:03 +0000 arcTo() -> should be "Adds a point to the current [subpath]..." 2010-10-05 12:59:07 +0000 1 1 1 Unclassified HTML WG pre-LC1 HTML Canvas 2D Context (editor: Ian Hickson) unspecified Other other CLOSED FIXED http://www.whatwg.org/specs/web-apps/current-work/#complex-shapes-(paths) P3 normal LC 1 contributor ian chrilith ian mike public-html-admin public-html-wg-issue-tracking public-html-bugzilla oldest_to_newest 35711 0 contributor 2010-05-15 10:16:03 +0000 Section: http://www.whatwg.org/specs/web-apps/current-work/complete.html#complex-shapes-(paths) Comment: arcTo() -> should be "Adds a point to the current [subpath]..." Posted from: 82.231.169.179 35712 1 chrilith 2010-05-15 10:24:49 +0000 Also, the explanation doesn't seem correct. In fact the two points (in current implementations) seem more like control points. And effective points are the ones at intersections between tangents an the circle. -- Adds two control points defining, using last point of previous subpath, 2 tangents to the circle defined by arguments. Resulting subpath is an arc starting at intersection point with the first tangent and ending at intersection point with the second tangent. -- Illustrated by the following example where the black disc is the previous subpath and gray ones control points. context.fillStyle = "gray"; context.beginPath(); context.translate(125, 25); context.moveTo(20,18); context.arcTo(40, 20, 10, 100, 100); context.lineTo(100, 100); context.stroke(); context.beginPath(); context.arc(40, 20, 4, 0, 2 * Math.PI, 1); context.arc(10, 100, 4, 0, 2 * Math.PI, 1); context.fill(); context.beginPath(); context.fillStyle = "black"; context.arc(20, 18, 4, 0, 2 * Math.PI, 1); context.fill(); 37815 2 contributor 2010-08-24 23:51:41 +0000 Checked in as WHATWG revision r5343. Check-in comment: correct some of the informative prose http://html5.org/tools/web-apps-tracker?from=5342&to=5343 37816 3 ian 2010-08-24 23:58:11 +0000 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: Accepted Change Description: see diff given below Rationale: I've changed the description to be less wrong. It's not especially useful, because I don't say how the control points work, but frankly there's a bunch of edge cases and it's pretty complicated, and I'm not sure how to define it helpfully. 37817 4 contributor 2010-08-24 23:58:37 +0000 Checked in as WHATWG revision r5344. Check-in comment: remove bad description of arcTo() http://html5.org/tools/web-apps-tracker?from=5343&to=5344 37825 5 chrilith 2010-08-25 07:24:03 +0000 Seems better. Also the full explanation later on the page may help to understand the principle.