Scrambled character bitmaps from FontSample for Monaco 10 from BDF

[nbriggs]

With the latest revision to the BDF font reader/display font writer, doing

(FontSample (FONTCREATE 'MONACO 10 'MRR 0 'DISPLAY)
     0 NIL 'DISPLAY T)

produces a font sample with scrambled bitmaps. It looks as though the character positions from the bitmap are offset by about half a character width. The FontSample output is attached. You should be able to reproduce this with the Monaco-10.bdf that was attached to my previous issue.

[MattHeffron]

This appears to be due to there being 3 characters that have 0 width of the glyph and a 0 width bitmap. I modified the BDF file to make the glyph widths = 1, and then it worked.

I checked and one of my test BDF files had some 0 width glyphs, but non-0 width bitmap. These are not in char set 0, so I never looked at them with FontSample. I may not have time to investigate further until Monday.

[nbriggs]

Also interesting - looking at the warnings generated by FontForge from loading the Monaco.ttf file:

The following table(s) in the font have been ignored by FontForge
Ignoring 'Zapf glyph reference table
Ignoring 'fasc' font descriptor table
Ignoring "fond" 'FOND' and 'NFNT' family compatibility table
Ignoring 'hdmx' horizontal device metrics table
Ignoring 'meta' metadata table
Bad lookup table: format=4 (40/41), first=65535 last=65535 total glyphs in font=1678
The glyph named commaaccent is mapped to U+021A.
But its name indicates it should be mapped to U+0162.
The glyph named commaaccent is mapped to U+021B.
But its name indicates it should be mapped to U+0163.
The glyph named zerowidthjoiner is mapped to U+200D
But its name indicates it should be mapped to U+FEFF.
The glyph named Ghemiddlehookcyrillic is mapped to U+0496.
But its name indicates it should be mapped to U+0494.
The glyph named ghemiddlehookcyrillic is mapped to U+0497.
But its name indicates it should be mapped to U+0495.
The glyph named sixroman is mapped to U+2179.
But its name indicates it should be mapped to U+2175.
The glyph named uni 2094 is mapped to U+2071.
But its name indicates it should be mapped to U+2094.
The glyph named uni20C8 is mapped to U+20A0.
But its name indicates it should be mapped to U+20C8.

I don't know whether these will result in a BDF file that has things in the wrong place...

[MattHeffron]

The file cu12.bdf.gz includes characters with the glyph width of 0, but bitmap width non-0.
E.g., U+0300, U+0301, which map to XCCS 0301, 0302, the non-spacing Grave and Acute accent characters. These are correctly rendered in FontSample.

[MattHeffron]

I have a fix for this. At least, with the Monaco-10.bdf provided with issue #2107, it doesn't have the corruption shown.
I have included it in PR #2108 (and I have edited the description there).