1663380 - SVG textPath startOffset - curved text is not positioned correctly in Firefox

Status: NEW

(Core :: SVG, defect)

Description

[Karl Dubost💡 :karlcow]

As reported on https://webcompat.com/issues/57434

In Firefox my curved text (SVG text on circular path) is rotated slightly counterclockwise from the expected position. Seems okay when viewed in Chrome or Edge. Problem only seems to happen if word-spacing / letter-spacing attributes are specified. It looks like a FF bug to me.

<svg width="600" height="300">
  <defs>
    <path id="arc" d="M 100 300 A 200 200 0  0 1 500 300"></path>
  </defs>
  <text>
    <textPath text-anchor="middle" style="font-size: 30; letter-spacing: 24; word-spacing:18" href="#arc" startOffset="50%">ABCDE ABCDE</textPath>
  </text>
  <line x1="0" y1="224" x2="600" y2="224" style="stroke:black; strokeWidth:0.5"></line>
</svg>

Setting the to startOffset="52%" (Firefox) gets the equivalent position for startOffset="50%" (Chrome)

Comment 1

[Robert Longson [:longsonr]]

Attachment: reporter's testcase

Comment 2

[Robert Longson [:longsonr]]

Attachment: reporter's testcase with valid units