[XeTeX] New feature planned for xetex

[Jonathan Kew]

On 18/2/16 14:02, Jiang Jiang wrote:
> Hi Jonathan,
> I suppose not everyone have a chance to build and try this yet. By any
> chance you can provide a PDF test case demonstrating the feature? Then
> perhaps more people can comment.

Here's an example in Urdu script. There are 3 pages, all containing the 
exact same text.

Page 1 has \XeTeXinterwordspaceshaping = 0, so this is what existing 
xetex would produce.

Page 2 has \XeTeXinterwordspaceshaping = 1, which allows the font to 
kern across the inter-word spaces; in some cases this makes the space 
width substantially negative, so that adjacent words actually "overlap" 
to some degree. This avoids the large visual "gaps" that sometimes occur 
on page 1, depending on the shapes of the adjacent words.

Page 3 has \XeTeXinterwordspaceshaping = 2, so we get the exact same 
line-breaks as page 2, but with some (relatively subtle, mostly) 
improvements to the actual shaping at word boundaries.

Hope this helps to illustrate why this feature is important (in certain 
specialized cases).

JK

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