bugFree UCS Outline Fonts - Bugs: bug #52385, Overlapping Malayalam below-base...


bug #52385: Overlapping Malayalam below-base glyphs

Submitted by:  David Corbett <dscorbett>
Submitted on:  Fri 10 Nov 2017 03:25:26 AM UTC  
Category:  character range Severity:  3 - Normal
Item Group:  letter positioning poor Status:  Proceeding
Privacy:  Public Assigned to:  Steve White <Stevan_White>
Open/Closed:  Open Release:  development

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Fri 17 Nov 2017 11:55:15 AM UTC, comment #4:

Hi Nandakumar,

The problem here is that it is possible to type something, wrong or right, that results in a graphical mess of overlying glyphs, or worse, a typo hidden because one glyph lies on top of another.

It would be best if we can eliminate that. If someone types something wrong, they should see the incorrect typing clearly, so they can spot it and correct it.

This has something to do with the font technology being used. If a separate glyph is made for each possible combination, it is reasonable to limit those to combinatons that really occur. However, I'm minimizing the glyphs in the font (for several practical reasons), by using other technologies such as glyph replacement and positioning. But this increases the possibilities of problems like those mentioned above. It's a trade-off.


Steve White <Stevan_White>
Project AdministratorIn charge of this item.
Fri 17 Nov 2017 07:38:21 AM UTC, comment #3:

The first four combos in David's list are never used in practice. The last one is used while transcribing English words like 'Split'. But what was the fifth one?

Nandakumar Edamana <nandakumar>
Project Member
Fri 10 Nov 2017 04:44:32 PM UTC, comment #2:

This was worse than I thought. The easy bit was that an anchor was missing to place one of the vocalics.

Much uglier: need to block base-forms in inappropriate circumstances. But what's inappropriate? Also, I think you are generating these things in ways I don't compeltely understand, inasmuch as they are of various natures.

I made what I think is a fix in serif normal only. It's a mess. I'll have to copy it into four tables in each of the four fonts. This is what you would call "fragile". Please test this face. When we're satisfied, I'll copy it into the other faces.

Steve White <Stevan_White>
Project AdministratorIn charge of this item.
Fri 10 Nov 2017 11:07:22 AM UTC, comment #1:

Yeah. a subscript consonant is being formed even when it is followed by a further consonant in the conjunct that doesn't make sense. In this case, no subcript should be formed. They should appear in-line with candrakalas, so it's clear what is going on.

Steve White <Stevan_White>
Project AdministratorIn charge of this item.
Fri 10 Nov 2017 03:25:26 AM UTC, original submission:

Many combinations of Malayalam below-base glyphs overlap each other. Here is a small sample.


David Corbett <dscorbett>


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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-11-10 Stevan_White StatusConfirmed => Proceeding
    2017-11-10 Stevan_White StatusNone => Confirmed
        Assigned toNone => Stevan_White

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