- From: Jon Knowles via GitHub <sysbot+gh@w3.org>
- Date: Fri, 14 Feb 2020 19:56:25 +0000
- To: public-texttracks@w3.org
jonknowles has just created a new issue for https://github.com/w3c/webvtt:
== Clarification of correct line position for vertical-rl and vertical-lr cues ==
I have a question about the specification for line position for vertical text cues. For cues with either a vertical:rl or vertical:lr property, the spec seems to state that the line position is relative to the direction of growth:
> The line offsets the cue box from the top, the right or left of the video viewport as defined by the writing direction, the snap-to-lines flag, or the lines occupied by any other showing tracks.
https://www.w3.org/TR/webvtt1/#webvtt-cue-line
However, it doesn't seem to explicitly state which side is at line 0% and which side is at line 100% for each growth direction.
The videojs/vtt.js project implements the line position as a percentage from the left side for vertical:rl and a percentage from the right side for vertical:lr, so the following cues are placed so:
```
00:00:06.000 --> 00:00:08.000 line:10% vertical:rl
text
________________________________
| t |
| e |
| x |
| t |
|________________________________|
00:00:06.000 --> 00:00:08.000 line:90% vertical:rl
text
________________________________
| t |
| e |
| x |
| t |
|________________________________|
```
To me, this seems the opposite of a common-sense interpretation, since 'rl' ('vertical growing left'), seems to imply that we start on the right at line position 0 and grow leftward toward line position 100. In my mind, the position of these two cues should be reversed, with line:10% on the right side of the screen and line:90% on the left side of the screen.
Is there something I am missing in the spec that lays this out explicitly? Is the videojs/vtt.js implementation of this positioning correct?
Please view or discuss this issue at https://github.com/w3c/webvtt/issues/481 using your GitHub account
Received on Friday, 14 February 2020 19:56:27 UTC