[ttml1] lineHeight "computed" vs "specified" inheritance

palemieux has just created a new issue for 
https://github.com/w3c/ttml1:

== lineHeight "computed" vs "specified" inheritance ==
Section 8.4.4.2(6)(b) specifies that `lineHeight` is set to its 
initial value of `"normal"` on `<region>`.

Section 8.4.4.2(6)(c) specifies that `<body>` will inherit the 
_computed value_ of `lineHeight` from its parent `<region>`.

The computed value of `lineHeight` on `<region>` is, say, 125% of the 
computed value of `fontSize` on `<region>`, so `1.25/15rh`.

So the computed values of `lineHeight` and `fontSize` on `<body>` are 
`1.25/15rh` and `4/15rh`, respectively.

These computed values are then propagated down by inheritance to the 
`<p>`, where "Hello" and "Bye" will overlap since the font size is 
significantly larger than the line height.

Is this the intended outcome and correct interpretation, or 
alternatively should initial values only be applied to elements to 
which the styles applies or does "normal" have special inheritance 
rules?

```
<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/ns/ttml" 
xmlns:tts="http://www.w3.org/ns/ttml#styling">
    <head>
        <layout>
            <region xml:id="bottom" tts:origin="10% 10%" 
tts:extent="80% 80%" />
        </layout>
    </head>
    <body tts:fontSize="4c">
        <div>
            <p region="bottom" begin="00:00:10.000" 
end="00:00:20.000">Hello<br/>Bye</p>
        </div>
    </body>
</tt>
```

NOTE: `1 rh` equals the computed height of root container.

Please view or discuss this issue at 
https://github.com/w3c/ttml1/issues/220 using your GitHub account

Received on Saturday, 12 November 2016 22:18:23 UTC