[ttml2] shear calculations and origin of coordinate system (#1199)

cconcolato has just created a new issue for https://github.com/w3c/ttml2:

== shear calculations and origin of coordinate system ==
TTML2 specifies how to perform [shear calculations](https://www.w3.org/TR/ttml2/#semantics-style-procedures-shear), in which it gives the transformation matrix to apply. However, it does not specify the origin of the coordinate system. This was discussed in the TTWG [here](https://www.w3.org/2020/02/13-tt-minutes.html#x04). If we cannot agree on spec text for the positioning of the origin, I'd suggest at least adding a note indicating: 
a) differences if any in the origin selection between shear, lineShear and fontShear; 
b) properties that may affect it (e.g. writingMode, textAlign/multiRowAlign, textCombine, ...)
c) that it may have consequences on layout and that there may be differences between implementations

Please view or discuss this issue at https://github.com/w3c/ttml2/issues/1199 using your GitHub account

Received on Thursday, 13 February 2020 17:32:38 UTC