A font vertical metrics reporting and line spacing adjustment tool
Source Repository: https://github.com/source-foundry/font-line
Issue Tracker and Reporting: https://github.com/source-foundry/font-line/issues
font-line is a libre, open source command line tool for OpenType vertical metrics reporting and command line based font line spacing modifications. It currently supports .ttf and .otf font builds.
font-line is built with Python and can be used on systems with Python 2.7+ and Python 3.3+ interpreters, including current releases of pypy and pypy3. You can verify your installed Python version on the command line with the command:
$ python --version
Use either of the following methods to install font-line on your system.
The latest font-line release is available through the Python Package Index and can be installed with pip:
$ pip install font-line
To upgrade to a new version of font-line after a pip install, use the command pip install --upgrade font-line.
The current repository version (which may be ahead of the PyPI release) can be installed by downloading the repository or cloning it with git:
git clone https://github.com/source-foundry/font-line.git
Navigate to the top level repository directory and enter the following command:
$ python setup.py install
Follow the same instructions to upgrade to a new version of the application if you elect to install with this approach.
font-line works via sub-commands to the font-line command line executable. The following sub-commands are available:
Usage of these sub-commands is described in detail below.
The following OpenType vertical metrics values and calculated values derived from these data are displayed with the report sub-command:
Enter one or more font path arguments to the command:
$ font-line report [fontpath 1] <fontpath ...>
Here is an example of the report generated with the Hack typeface file Hack-Regular.ttf using the command:
$ font-line report Hack-Regular.ttf
=== Hack-Regular.ttf === Version 2.020;DEV-03192016; SHA1: 638f033cc1b6a21597359278bee62cf7e96557ff --- Metrics --- [head] Units per Em: 2048 [head] yMax: 2001 [head] yMin: -573 [OS/2] TypoAscender: 1556 [OS/2] TypoDescender: -492 [OS/2] WinAscent: 1901 [OS/2] WinDescent: 483 [hhea] Ascent: 1901 [hhea] Descent: -483 [hhea] LineGap: 0 [OS/2] TypoLineGap: 410 --- Height Calculations by Table Values --- [OS/2] TypoAscender to TypoDescender: 2048 [OS/2] WinAscent to WinDescent: 2384 [hhea] Ascent to Descent: 2384 --- Delta Values --- WinAscent to TypoAscender: 345 Ascent to TypoAscender: 345 WinDescent to TypoDescender: -9 Descent to TypoDescender: -9 --- Ratios --- (Typo Asc + Desc + Linegap) / UPM: 1.2 (winAsc + winDesc) / UPM: 1.16 (hhea Asc + Desc) / UPM: 1.16
The report includes the font version string, a SHA-1 hash digest of the font file, and OpenType table metrics that are associated with line spacing in the font.
Unix/Linux/OS X users can write this report to a file with the > command line idiom:
$ font-line report TheFont.ttf > font-report.txt
You can modify font-report.txt to the file path of your choice.
font-line supports automated line spacing modifications to a user-defined percentage of the units per em metric. This value will be abbreviated as UPM below.
Enter the desired percentage of the UPM as the first argument to the command. This should be entered as an integer value. Then enter one or more font paths to which you would like to apply your font metrics changes.
$ font-line percent [percent change] [fontpath 1] <fontpath ...>
A common default value used by typeface designers is 20% UPM. To modify a font on the path TheFont.ttf to 20% of the UPM metric, you would enter the following command:
$ font-line percent 20 TheFont.ttf
Increase or decrease the integer value to increase or decrease your line spacing accordingly.
The original font file is preserved in an unmodified version and the modified file write takes place on a new path defined as [original filename]-linegap[percent].[ttf|otf]. The path to the file is reported to you in the standard output after the modification is completed. font-line does not modify the glyph set or hints applied to the font. See the Details section below for a description of the OpenType table modifications that occur when the application is used on a font file.
You can inspect the vertical metrics in the new font file with the report sub-command (see Usage above).
The interpretation and display of these multiple vertical metrics values is platform and application dependent. There is no broadly accepted “best” approach. As such, font-line attempts to preserve the original metrics design in the font when modifications are made with the percent sub-command.
font-line currently supports three commonly used vertical metrics approaches.
Vertical Metrics Approach 1:
Where metrics are defined as:
font-line calculates a delta value for the total expected height based upon the % UPM value defined on the command line. The difference between this value and the observed number of units that span the [OS/2] winAscent to winDescent values is divided by half and then added to (for increased line spacing) or subtracted from (for decreased line spacing) each of the three sets of Ascender/Descender values in the font. The [OS/2] TypoLinegap and [hhea] linegap values are not modified.
Vertical Metrics Approach 2
Where metrics are defined as:
font-line calculates a delta value for the total expected height based upon the % UPM value defined on the command line. The difference between this value and the observed number of units that span the [OS/2] winAscent to winDescent values is divided by half and then added to (for increased line spacing) or subtracted from (for decreased line spacing) the [OS/2] winAsc/winDesc and [hhea] Asc/Desc values. The [OS/2] TypoAsc/TypoDesc values are not modified and maintain a definition of size = UPM value. The [OS/2] TypoLinegap and [hhea] linegap values are not modified.
Vertical Metrics Approach 3
Where metrics are defined as:
Changes to the metrics values in the font are defined as:
Note that the internal leading modifications are split evenly across [hhea] Ascent & Descent values, and across [OS/2] WinAscent & WinDescent values. We add half of the new [OS/2] TypoLineGap value to the original [OS/2] TypoAscender or TypoDescender in order to define these new metrics properties. The [hhea] linegap value is always defined as zero.
The newly defined vertical metrics values can lead to clipping of glyph components if not properly defined. There are no tests in font-line to provide assurance that this does not occur. We assume that the user is versed in these issues before use of the application and leave this testing to the designer / user before the modified fonts are used in a production setting.
Please submit a new issue report on the project repository.
font-line is built with the fantastic fontTools Python library.
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
|File Name & Checksum SHA256 Checksum Help||Version||File Type||Upload Date|
|font_line-0.6.0-py2.py3-none-any.whl (14.7 kB) Copy SHA256 Checksum SHA256||2.7||Wheel||Apr 8, 2016|
|font-line-0.6.0.tar.gz (13.8 kB) Copy SHA256 Checksum SHA256||–||Source||Apr 8, 2016|