FontBLF: Store Sizes, Styles, and Other Metrics #113432

Harley Acheson · 2023-10-09T00:14:49+02:00

Harley Acheson commented

2023-10-09 00:14:49 +02:00

When loading a font, gather metrics and other information that can help
use it more correctly. Default weight and slant, X-height, cap height,
locations for underline, strike-through, subscripts, etc. Family and
style flags, etc.

This PR, on its own, has no effects. It simply gathers and stores values that could be used to help us use the font in better and more typographically correct ways.

Some of this data could be obtained directly from the FT_Face at any time, but we are wanting to sometimes run with FontBLFs that are without faces all the time when not needed. Other data is taken from the font's OS/2 and Post tables, while other data is calculated. The data includes:

weight - the font's default weight (100-900)
width - condensed versus wide in a range, with 1 as normal
slant - in clockwise degrees
x-height - distance from baseline to lowercase mean line
cap height - distance from baseline to the top of capital letters
much, much more...

PR #112454 would use the data here to find the starting default weights, slant values, widths, etc. Because that PR sets absolute values, rather than make relative changes, it needs the starting position. For example, it allows changing the weight of any font to be in the range of 100-900 weight class, but how much is done depends on the starting weight of the font, which might be a non-variable light or heavy version. Similarly it allows setting any slant in positive or negative degrees, but it needs to know if the font already starts with a slant.

PR #110187 would need the data here to determine the starting vfont scale without needing to use FreeType directly itself. And it could later use the data to make the output more correct. For example, "small caps" is meant to be at x-height. Underline is best set at a location and thickness specified by the font designer. We might want to eventually set the initial scale based on cap height so that fonts have a more consistent size. We could even use the family and style and other data to allow working with a full family of fonts, not just the four font variations we accept now. We could allow setting of subscript and superscript since this data includes the information on how to construct those.

When loading a font, gather metrics and other information that can help use it more correctly. Default weight and slant, X-height, cap height, locations for underline, strike-through, subscripts, etc. Family and style flags, etc. --- This PR, on its own, has no effects. It simply gathers and stores values that _could_ be used to help us use the font in better and more typographically correct ways. Some of this data could be obtained directly from the FT_Face at any time, but we are wanting to sometimes run with FontBLFs that are without faces all the time when not needed. Other data is taken from the font's OS/2 and Post tables, while other data is calculated. The data includes: * weight - the font's default weight (100-900) * width - condensed versus wide in a range, with 1 as normal * slant - in clockwise degrees * x-height - distance from baseline to lowercase mean line * cap height - distance from baseline to the top of capital letters * much, much more... PR #112454 would use the data here to find the starting default weights, slant values, widths, etc. Because that PR sets absolute values, rather than make relative changes, it needs the starting position. For example, it allows changing the weight of any font to be in the range of 100-900 weight class, but how much is done depends on the starting weight of the font, which might be a non-variable light or heavy version. Similarly it allows setting any slant in positive or negative degrees, but it needs to know if the font already starts with a slant. PR #110187 would need the data here to determine the starting vfont scale without needing to use FreeType directly itself. And it could later use the data to make the output more correct. For example, "small caps" is meant to be at x-height. Underline is best set at a location and thickness specified by the font designer. We might want to eventually set the initial scale based on cap height so that fonts have a more consistent size. We could even use the family and style and other data to allow working with a full family of fonts, not just the four font variations we accept now. We could allow setting of subscript and superscript since this data includes the information on how to construct those.

Harley Acheson added 1 commit 2023-10-09 00:15:03 +02:00

293606fc54 FontBLF: Store Sizes, Styles, and Other Metrics

When loading a font, gather metrics and other information that can help
use it more correctly. Default weight and slant, X-height, cap height,
locations for underline, strike-through, subscripts, etc. Family and
style flags, etc.

Harley Acheson added this to the Core project 2023-10-09 00:15:12 +02:00

Harley Acheson added 2 commits 2023-10-12 01:43:07 +02:00

66dd07942e Merge branch 'main' of projects.blender.org:blender/blender into FontMetrics

buildbot/vexp-code-patch-coordinator Build done. Details

19865f4f62 Comment changes

Harley Acheson commented

2023-10-12 01:45:31 +02:00

@blender-bot build

Harley Acheson commented

2023-10-12 17:47:53 +02:00

Notes:

I think I should add one more metric, the proportion of width to height of lowercase "O". This gives a nice indication of horizontal "Proportion" that could be useful for font comparisons, classification, sorting, replacement. https://medium.com/@getflourish/the-anatomy-of-a-thousand-typefaces-f7b9088eed1

Since blf_font_metrics is made to work with just an FT_Face as input, and does not depend on FontBLF, make sure it is in a nice place that it could be used by thumbnail code. This way some information could be added to the thumbnail meta-data and shown on the hover tooltip.

Notes: I think I should add one more metric, the proportion of width to height of lowercase "O". This gives a nice indication of horizontal "Proportion" that could be useful for font comparisons, classification, sorting, replacement. https://medium.com/@getflourish/the-anatomy-of-a-thousand-typefaces-f7b9088eed1 Since `blf_font_metrics` is made to work with just an FT_Face as input, and does not depend on FontBLF, make sure it is in a nice place that it could be used by thumbnail code. This way some information could be added to the thumbnail meta-data and shown on the hover tooltip.

Harley Acheson added 3 commits 2023-10-12 21:47:32 +02:00

49c6471b91 Merge branch 'main' of projects.blender.org:blender/blender into FontMetrics

9637d98d4c Merge branch 'main' of projects.blender.org:blender/blender into FontMetrics

c3a5411208 o_proportion.

Harley Acheson commented

2023-10-12 23:37:21 +02:00

I want to work on a (simplified) variation of #112454 for inclusion before the Conference. Therefore I need this before the weekend.