UI: Improved Initial Vfont Sizes #109228

Harley Acheson · 2023-06-22T05:47:49+02:00

Harley Acheson commented

2023-06-22 05:47:49 +02:00

Better consistency between initial text object sizes by using Cap
height instead of maximum bounding box height.

Text objects can obviously be scaled to any size. But the initial sizes, when the text is first added, create a lot of variation in the visual size of different fonts. With Blender 4.0 it might be a nice time to improve this.

This problem occurs now because we base the initial scale on the maximum top and bottom of all the glyphs in the font, which is not a normal metric for this use. If you start with two identically-designed fonts that just have coverage of lower Latin and then add extra characters outside of that range to one then it will be shown as smaller in Blender. This is because it is more likely to contain characters, like symbols, that might extend further above or below the other characters. This will increase the maximal vertical range and result in a smaller scale.

The most normal metric to keep different fonts at nearly the same size is to use Cap height, or the height of a capital letter above the baseline. Specifically it is the height of flat capitals (like H or I), rather than rounded (O) or pointed (A). So the informal definition is the height of a capital H.

This PR refactors the scale calculations to use Cap height. But then scales the result so that our default font is the same height as it is today. This also means that most sane fonts - that have capitals that take up the space between baseline and top of the em-square are also that same height.

Following shows an assortment of fonts at initial sizes in current code:

The following shows the same fonts with this PR.:

You should notice that the second image has improved consistency. It is not perfect though, as that is impossible, because font designers are free to make glyphs of any size within their design sizes. But you should notice that for most of the "normal" fonts the tops of the "f" are perfectly aligned.

This PR first checks to see if the font itself actually defines a "cap height" metric within it. If not, this falls back to measuring the height of an "H". And if the font does not contain an "H" then it uses 70% of design height.

Note that with this code change VFontData->em_height would always be exactly 1.0f. As in the font is 1em high and then scaled by VFontData->scale. This em_height was never needed but sometimes had a non-one value because of the current wonky calculations. So this PR removes it, simplifying some other calculations.

Better consistency between initial text object sizes by using Cap height instead of maximum bounding box height. --- Text objects can obviously be scaled to any size. But the initial sizes, when the text is first added, create a lot of variation in the visual size of different fonts. With Blender 4.0 it might be a nice time to improve this. This problem occurs now because we base the initial scale on the maximum top and bottom of all the glyphs in the font, which is not a normal metric for this use. If you start with two identically-designed fonts that just have coverage of lower Latin and then add extra characters outside of that range to one then it will be shown as _smaller_ in Blender. This is because it is more likely to contain characters, like symbols, that might extend further above or below the other characters. This will increase the maximal vertical range and result in a smaller scale. The most normal metric to keep different fonts at nearly the same size is to use Cap height, or the height of a capital letter above the baseline. Specifically it is the height of flat capitals (like H or I), rather than rounded (O) or pointed (A). So the informal definition is the height of a capital H. This PR refactors the scale calculations to use Cap height. But then scales the result so that our default font is the same height as it is today. This also means that most sane fonts - that have capitals that take up the space between baseline and top of the em-square are also that same height. Following shows an assortment of fonts at initial sizes in current code: ![image](/attachments/519bba81-859e-458d-8705-bb0333a686bc) The following shows the same fonts with this PR.: ![image](/attachments/ebc6a60d-354e-474b-9d50-c32e9867aa36) You should notice that the second image has improved consistency. It is not perfect though, as that is impossible, because font designers are free to make glyphs of any size within their design sizes. But you should notice that for most of the "normal" fonts the tops of the "f" are perfectly aligned. This PR first checks to see if the font itself actually defines a "cap height" metric within it. If not, this falls back to measuring the height of an "H". And if the font does not contain an "H" then it uses 70% of design height. Note that with this code change VFontData->em_height would always be exactly 1.0f. As in the font is 1em high and then scaled by VFontData->scale. This em_height was never needed but sometimes had a non-one value because of the current wonky calculations. So this PR removes it, simplifying some other calculations.

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Harley Acheson added this to the User Interface project 2023-06-22 05:48:45 +02:00

Harley Acheson requested review from Hans Goudey 2023-06-22 17:12:45 +02:00

Hans Goudey approved these changes 2023-06-23 13:55:53 +02:00

Hans Goudey left a comment

I don't know too much about this area, but the description makes sense, and the code change looks reasonable to me. 4.0 does seem like a nice time to change this.

Harley Acheson requested review from Campbell Barton 2023-06-24 00:49:34 +02:00

Harley Acheson commented

2023-06-24 00:55:22 +02:00

@ideasman42 - What do you think of this?

On the one hand it would be nice to finally clean this up. Users could (generally) replace one normal font with one of similar design and have them be the same height.

On the other hand we end up with small font size differences for files made prior to 4.0. Is it worth the hassle or is 4.0 the first and best chance to do this? Not sure.

@ideasman42 - What do you think of this? On the one hand it would be nice to finally clean this up. Users could (generally) replace one normal font with one of similar design and have them be the same height. On the other hand we end up with small font size differences for files made prior to 4.0. Is it worth the hassle or is 4.0 the first and best chance to do this? Not sure.

Harley Acheson force-pushed vfontsize from d67265957c to 70d810682f

2023-07-14 01:48:17 +02:00

Compare

Hans Goudey commented

2023-07-14 14:48:17 +02:00

How complex would it be to add versioning that scales the text height by the difference in the new behavior? Then the different results in 4.0 argument wouldn't apply. That breaking change does make me a bit hesitant about this too actually.

Harley Acheson commented

2023-07-20 23:25:30 +02:00

Actually I also don't like having this change of behavior between versions for so little gain.

Harley Acheson closed this pull request

2023-07-20 23:25:32 +02:00

Pull request closed

Please reopen this pull request to perform a merge.

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UI: Improved Initial Vfont Sizes #109228

Pull request closed