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Re: [groff] Now online: gropdf / grops previewer


From: G. Branden Robinson
Subject: Re: [groff] Now online: gropdf / grops previewer
Date: Sun, 22 Apr 2018 19:34:20 -0400
User-agent: NeoMutt/20170113 (1.7.2)

At 2018-04-23T09:04:25+1000, John Gardner wrote:
> Well, here it is:
> 
> https://rawgit.com/Alhadis/Roff.js/web-demo/index.html
> 
> Some modifications were needed for web-delivery, and performance still
> isn't optimal, but it works. You'll need a relatively recent browser to use
> it (anything released within the last year should do).
> 
> Few things to note before you try it:

This looks fantastic!  Thank you for doing this work!

I'd love to see what the source looks like, but when I alter the URL, I
get a bunch of 404s.

>    - *Some fonts may look different.* Browsers handle font-rendering, which
>    means the base 35 PDF fonts won't be visible in the renderer unless they've
>    also been installed in your system's usual fonts directory.

I found a possible Unicode handling problem.  In the attached ditroff
output, note that the angle brackets around the email address in the
"AUTHORS" section are rendered as different glyphs altogether.

>    - *There's an issue with zooming.* This is what I'm stuck on, and when
>    Branden offered help with matrix calculations, I decided the best way of
>    explaining was with a working demo.
> 
>    If you zoom in using the *100%* menu, you'll notice you can't scroll
>    left or upwards. That's because the page contents extend past the top-left
>    corner of the browser window, and we all know you can't scroll past the
>    window's origin corner.

I see what you mean.  I don't think there's a matrix math problem here.
If I had to guess, you are doing a coordinate transform from document
coordinates to canvas (and/or browser window) coordinates, and clamping
the wrong pair.

For instance, if I zoom a document to 150%, there is obviously document
content off-screen to the left.  So the x coordinate is negative in the
browser window, but of course it is still positive in the document's
coordinate frame.

I know nothing about JavaScript frameworks (apart from the existence of
this "canvas" thing, which is a fairly generic term for a drawing window
anyway).

Anyway, if I can get my hands on the source, maybe we can put our heads
together on the problem.

Great work!

-- 
Regards,
Branden

Attachment: pic2graph.1.ditroff
Description: Text document

Attachment: signature.asc
Description: PGP signature


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