1129854 - SVG markers not oriented correctly for degenerate beziers

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[Paul LeBeau]

Attachment: markers_degenerate_CP.svg

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
Build ID: 20150122214805

Steps to reproduce:

When the control point vector of a bezier is zero length, the orientation of a marker at that point is being rendered incorrect.  Blink is defaulting to the "slope cannot be determined" behaviour which results in an orientation of 0.

The slope at such a vertex is still determinable, so this degenerate case should be handled correctly.

<svg>
  <defs>
    <marker id="Triangle"
      refX="0" refY="12" markerUnits="userSpaceOnUse"
      markerWidth="24" markerHeight="24" orient="auto">
      <path d="M 0 0 L 24 12 L 0 24 z" />
    </marker>
  </defs>

  <!-- CP vectors are zero.  Orientation should still work. -->

  <path d="M 50,125 C 50,125, 100,25, 100,25" stroke-width="10" stroke="red"
    marker-end="url(#Triangle)" />

  <path d="M 150,125 C 200,25, 200,25, 200,25" stroke-width="10" stroke="red"
    marker-end="url(#Triangle)" />

</svg>





Actual results:

Marker rendered at 0 degrees


Expected results:

Marker rendered at the same orientation as the line

Comment 1

[Robert Longson [:longsonr]]

Attachment: markers_degenerate_CP.svg

Comment 2

[Paul LeBeau]

Forgive the Blink reference.  C&P error.  I reported the same bug in Chrome.

Comment 3

[Robert Longson [:longsonr]]

Attachment: degenerate.txt

Comment 4

[Robert Longson [:longsonr]]

Attachment: simplify code

Comment 5

[Robert Longson [:longsonr]]

Attachment: without random turbulence change this time

Comment 6

[Jonathan Watt [:jwatt]]

Comment on attachment 8564614 [details] [diff] [review]
without random turbulence change this time

Had meant to r+ this.

Comment 7

[Robert Longson [:longsonr]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=0bdbcd2cddb1

Comment 8

[Robert Longson [:longsonr]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/04527ab4352c

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/04527ab4352c