Box Drawing & Block Elements Unicode Blocks

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PJMiller
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Box Drawing & Block Elements Unicode Blocks

Postby PJMiller » Tue Jan 19, 2016 8:27 pm

In order for my font 'Kelvinch' to be compliant with WGL4 (http://en.wikipedia.org/wiki/Windows_Glyph_List_4) it needs some of the Block Elements ($2580 to $259F) unicode block and some of the Box Drawing ($2500 to $257F) unicode block.

My first observation is that Kelinch is a proportional font so rendering a table with these characters it is likely that the right hand sides of any box which contains text will not line up.

Secondly I have a question :- Is the 'Win Ascent' line of one character also the 'Win Descent' line of the character above? If not then there will be a gap. Experiments I have carried out show that any part of a character which appears over the 'Win Ascent' line is not rendered by any of the software I have tried it on. The same goes for the 'Win Descent' line, any part of a character which is below the 'Win Descent' line is not reproduced.

So am I right in thinking that the Box Drawing characters have to go vertically from the 'Win Ascent' line to the 'Win Descent' line and horizontally the Left Side Bearing and the Right Side Bearing must be zero or -1 (unless the glyph does not extend to that side of the character, for example the vertical line $2503)?

Bhikkhu Pesala
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Re: Box Drawing & Block Elements Unicode Blocks

Postby Bhikkhu Pesala » Tue Jan 19, 2016 9:21 pm

Yes, you will have problems producing tables with text. I am not sure why anyone needs to do this nowadays using line draw characters.

Yes also to the WinAscent/Descent issue.

Test your font in the Font Test Window (F5) Here's a quick test with the Vertical Bar |

Block Glyphs.png
Block Glyphs.png (14.08 KiB) Viewed 2256 times
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PJMiller
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Re: Box Drawing & Block Elements Unicode Blocks

Postby PJMiller » Tue Jan 19, 2016 11:38 pm

Bhikkhu Pesala wrote:I am not sure why anyone needs to do this nowadays using line draw characters.


They are not necessary, not in these days of desktop publishing where any word processor worthy of the name can lay out tables correcly without these characters.

I'm just being cynical here, if these characters are present I can claim that Kelvinch is WGL4 compliant, it already has most of the characters, the only things missing were the Box Drawing characters, the Block Elements, a couple of archaic currency symbols which are no longer used and a pair of math symbols which I was going to put in anyway.

The Box Drawing characters are very simple to do.

Usually I would fill the blocks but in this instance I am just going to do the minimum necessary to be WGL4 compliant. But they are going to be done right!

Alfred
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Re: Box Drawing & Block Elements Unicode Blocks

Postby Alfred » Wed Jan 20, 2016 9:58 pm

PJMiller wrote:So am I right in thinking that the Box Drawing characters have to go vertically from the 'Win Ascent' line to the 'Win Descent' line and horizontally the Left Side Bearing and the Right Side Bearing must be zero or -1 (unless the glyph does not extend to that side of the character, for example the vertical line $2503)?

In Quivira, where WinAscent is 1900 and WinDescent is -510 funits, glyphs such as 'shade' at codepoint $2592 go from 2000 to -800 funits.

Quivira_shade.png
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PJMiller
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Re: Box Drawing & Block Elements Unicode Blocks

Postby PJMiller » Fri Jan 22, 2016 10:47 pm

I thought that the way it was supposed to work was that the glyph rendering stopped at the Win Ascent line and the Win Descent line but this appears not to be the case.

My earlier experiments were done at large point sizes.

Further experimentation revealed that the rendering extends beyond the Win Ascent and Win Descent lines but it is variable. At large point sizes there is very little overspill but as the point size goes down a variable amount of the glyph beyond the line is displayed. But it is unpredictable and the biggest overspill didn't occur at the smallest point size. The ratio of overspill to point size is not a continuous linear function.

Anyway I now have some shading characters which work well at many point sizes. At some point sizes there are some discontinuities but I suspect nobody is ever going to use these characters for continuous shading anyway.

Whilst the FC font test window is active the font is temporarily installed in Windows and so a word processor doument which had large areas of shading characters and box drawing characters was prepared and every time the test window was activated the test document was re-formatted into the temporary font, then the point size could be adjusted and the whole process repeated.

After many iterations I got something which worked well enough.

PJMiller
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Re: Box Drawing & Block Elements Unicode Blocks

Postby PJMiller » Sat Jun 04, 2016 11:26 pm

Thankyou for your kind words.

It was started in January 2015 and finished (unless somebody finds more errors) in April 2016.

If you are interested the story of its creation is in the fontlog file.

Bhikkhu Pesala let me have the Geometric Shapes, Arrows, Dingbats Miscellaneous Symbols and a few other glyphs from his Pali Font.


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