Determine parameters for rendering a TextTrackCue

• Component: Media
• Status: RESOLVED FIXED

[Victor Carbune]

This bug represents inner substeps 10.1, 10.4 - 10.9 of section 3.5 of WebVTT rendering rules:
http://dev.w3.org/html5/webvtt/#webvtt-cue-text-rendering-rules

"10. For each text track cue cue in cues that has not yet had corresponding CSS boxes added to output, in text track cue order, run the following substeps:
10.1 Let nodes be the list of WebVTT Node Objects obtained by applying the WebVTT cue text parsing rules to the cue's text track cue text.
[...]"

[Victor Carbune]

Created attachment 132011 [details]
Preliminary patch

Implemented the computational steps described in the spec. The patch could be submitted stand-alone - as it is - or in the same time with the first implemented rendering case that is blocked by it.

[WebKit Review Bot]

Comment on attachment 132011 [details]
Preliminary patch

Attachment 132011 [details] did not pass chromium-ews (chromium-xvfb):
Output: http://queues.webkit.org/results/11954572

[Eric Carlson]

Comment on attachment 132011 [details]
Preliminary patch

View in context: https://bugs.webkit.org/attachment.cgi?id=132011&action=review

This is close, but it needs some clean-up and tests.

> Source/WebCore/html/track/TextTrackCue.cpp:128
> +    m_displayWritingModeMap[Horizontal] = CSSValueHorizontalTb;
> +    m_displayWritingModeMap[VerticalGrowingLeft] = CSSValueVerticalLr;
> +    m_displayWritingModeMap[VerticalGrowingRight] = CSSValueVerticalRl;

Nit: it would be good to have a comment here about why these are correct defaults.

> Source/WebCore/html/track/TextTrackCue.cpp:438
> +    int maximumSize;

This will remain uninitialized if none of the conditions below evaluate to true. Even if this can't logically happen, the compiler will complain.

> Source/WebCore/html/track/TextTrackCue.cpp:456
> +    m_displaySize = m_cueSize < maximumSize ? m_cueSize : maximumSize;

std::min() ?

> Source/WebCore/html/track/TextTrackCue.cpp:460
> +    // width be 'sizeâvw' and height be 'auto'. Otherwise, let width be 'auto'
> +    // and height be 'sizeâvh'. (These are CSS values used by the next section

Nit: "sizeâvw" and "sizeâvh" ?

> Source/WebCore/html/track/TextTrackCue.cpp:504
> +    // 10.10 Let left be 'x-positionâvw' and top be 'y-positionâvh'.

Nit: copy pasta here as well

> Source/WebCore/html/track/TextTrackCue.h:161
> +    int m_displayWritingModeMap[3];

WritingDirection is a private enum, so I think we should add a sentinel terminal value and use it here instead of hard coding the size of this array.

[Victor Carbune]

Submitted as part of https://bugs.webkit.org/show_bug.cgi?id=79750
Changeset 114640 (http://trac.webkit.org/changeset/114640)