Gather font metrics for FreeType fonts #76
Labels
P-linux
Any Linux OS capable of running Servo
Comments
|
Most of the metrics are there, but x-height and leading are still missing. |
|
Is this what is causing the issues shown here? Note the "mb" spacing in numbers and "me" and "mi" and "re" in several places. |
|
This looks like missing/wrong kerning or glyph advance information. Can you show a screenshot of firefox rendering the same page with the same font? |
|
Also, it should be finding an italicized font face for this test. Might be a separate bug. |
dhedlund
added a commit
to dhedlund/servo
that referenced
this issue
Dec 8, 2013
bors-servo
pushed a commit
that referenced
this issue
Dec 9, 2013
Fixes #76. Implemented the only font metric remaining to resolve issue #76 for the Linux platform. There are still some variations between Linux and OS X font metrics. Looking at values for the "Times New Roman" font, the following metrics differed by over 10%: `leading`, `x_height` and `max_advance`. It was not obvious if this would create any major difference in rendering, or whether the discrepancies would be handled in platform specific ways during the rendering process. Only `x_height` is being used by existing code. The `leading` property under Linux is still an order of magnitude off from the OS X version, but they are computed with similar calculations. Issue #1355 has been opened to further investigate the discrepancies. #### Platform comparison of font metrics for "Times New Roman" between Linux and OS X: **Au** is the raw metric values stored in the `FontMetrics` struct. **% of em** is how large that value is relative to the raw `em_size` of the font as a percentage. Linux reports the pt size differently than OS X, but this is probably because the linux platform uses hard-coded points-per-inch value (hard-coded in `src/components/util/geometry.rs`), whereas OS X uses the points-per-inch value provided by the font library. +-----------------------------------+ +-----------------------------------+ | Linux (@14.25pt, 1.33em) | | OS X (@19.35pt, 1.0em) | +------------------+------+---------+ +------------------+------+---------+ | property | Au | % of em | | property | Au | % of em | +------------------+------+---------+ +------------------+------+---------+ | underline_size | 55 | 4.82 | | underline_size | 60 | 5.17 | | underline_offset | -151 | -13.25 | | underline_offset | -120 | -10.34 | | strikeout_size | 56 | 4.91 | | strikeout_size | 0 | 0.00 | | strikeout_offset | 295 | 25.88 | | strikeout_offset | 0 | 0.00 | | leading | 541 | 47.45 | | leading | 60 | 5.17 | | x_height | 1015 | 89.04 | | x_height | 660 | 56.85 | | em_size | 1140 | 100.00 | | em_size | 1161 | 100.00 | | ascent | 1015 | 89.04 | | ascent | 893 | 76.92 | | descent | 246 | 21.58 | | descent | 203 | 17.48 | | max_advance | 1199 | 105.18 | | max_advance | 2820 | 242.89 | +------------------+------+---------+ +------------------+------+---------+ +-----------------------------------+ +-----------------------------------+ | Linux (@24pt, 1.33em) | | OS X (@32.683333pt, 1.0em) | +------------------+------+---------+ +------------------+------+---------+ | property | Au | % of em | | property | Au | % of em | +------------------+------+---------+ +------------------+------+---------+ | underline_size | 93 | 4.84 | | underline_size | 120 | 6.12 | | underline_offset | -255 | -13.28 | | underline_offset | -240 | -12.24 | | strikeout_size | 95 | 4.95 | | strikeout_size | 0 | 0.00 | | strikeout_offset | 496 | 25.83 | | strikeout_offset | 0 | 0.00 | | leading | 912 | 47.50 | | leading | 60 | 3.06 | | x_height | 1710 | 89.06 | | x_height | 1080 | 55.10 | | em_size | 1920 | 100.00 | | em_size | 1960 | 100.00 | | ascent | 1710 | 89.06 | | ascent | 1544 | 78.77 | | descent | 415 | 21.61 | | descent | 365 | 18.62 | | max_advance | 2020 | 105.21 | | max_advance | 4740 | 241.84 | +------------------+------+---------+ +------------------+------+---------+ +-----------------------------------+ +-----------------------------------+ | Linux (@45pt, 1.33em) | | OS X (@60.833333pt, 1.0em) | +------------------+------+---------+ +------------------+------+---------+ | property | Au | % of em | | property | Au | % of em | +------------------+------+---------+ +------------------+------+---------+ | underline_size | 175 | 4.86 | | underline_size | 180 | 4.93 | | underline_offset | -479 | -13.31 | | underline_offset | -480 | -13.15 | | strikeout_size | 179 | 4.97 | | strikeout_size | 0 | 0.00 | | strikeout_offset | 931 | 25.86 | | strikeout_offset | 0 | 0.00 | | leading | 1709 | 47.47 | | leading | 180 | 4.93 | | x_height | 3208 | 89.11 | | x_height | 2040 | 55.89 | | em_size | 3600 | 100.00 | | em_size | 3650 | 100.00 | | ascent | 3208 | 89.11 | | ascent | 2925 | 80.14 | | descent | 778 | 21.61 | | descent | 690 | 18.90 | | max_advance | 3788 | 105.22 | | max_advance | 8880 | 243.29 | +------------------+------+---------+ +------------------+------+---------+ +-----------------------------------+ +-----------------------------------+ | Linux (@30.75pt, 1.33em) | | OS X (@41.9pt, 1.0em) | +------------------+------+---------+ +------------------+------+---------+ | property | Au | % of em | | property | Au | % of em | +------------------+------+---------+ +------------------+------+---------+ | underline_size | 120 | 4.88 | | underline_size | 120 | 4.77 | | underline_offset | -327 | -13.29 | | underline_offset | -360 | -14.32 | | strikeout_size | 122 | 4.95 | | strikeout_size | 0 | 0.00 | | strikeout_offset | 636 | 25.85 | | strikeout_offset | 0 | 0.00 | | leading | 1168 | 47.47 | | leading | 120 | 4.77 | | x_height | 2192 | 89.11 | | x_height | 1440 | 57.27 | | em_size | 2460 | 100.00 | | em_size | 2514 | 100.00 | | ascent | 2192 | 89.11 | | ascent | 1991 | 79.20 | | descent | 532 | 21.63 | | descent | 487 | 19.37 | | max_advance | 2588 | 105.20 | | max_advance | 6120 | 243.44 | +------------------+------+---------+ +------------------+------+---------+
therealglazou
pushed a commit
to therealglazou/servo
that referenced
this issue
Feb 20, 2014
glennw
added a commit
to glennw/servo
that referenced
this issue
Jan 16, 2017
Unify clip rects and clip regions into a single "combined clip region" structure, and clip inset box shadows to rounded rectangle corners.
jdm
pushed a commit
to jdm/servo
that referenced
this issue
Mar 6, 2021
Increase default JS heap size (from 8MB -> 32 MB) for testing large pages.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
In order to do line-height and baseline calculations properly, inline layout needs access to font metrics. I have implemented basic metrics gathering for Mac (through the CoreText
CTFont*APIs). The same needs to be done for FreeType. I've stubbed out the implementation for now to return zero metrics.The text was updated successfully, but these errors were encountered: