Posts in Category "Building Fonts"

A Tale of Three (OpenType) Features

In an effort to make sure that the infrastructure to support UTR #50 (Unicode Vertical Text Layout) will be in place—sooner rather than later—I spent a significant part of last week working with key people within Adobe, and at Microsoft and W3C, to put together a proposal for a new OpenType feature, to be tagged ‘vrtr’, for supporting this soon-to-be published standard. Below is full description that we came up with, and which was submitted for inclusion in the OpenType Specification and in OFF (ISO/IEC 14496-22 or Open Font Format):

Tag: ‘vrtr’

Friendly name: Vertical Alternates For Rotation

Registered by: Adobe/Microsoft/W3C

Function: Transforms default glyphs into glyphs that are appropriate for sideways presentation in vertical writing mode. While the glyphs for most characters in East Asian writing systems remain upright when set in vertical writing mode, glyphs for other characters—such as those of other scripts or for particular Western-style punctuation—are expected to be presented sideways in vertical writing.

Example: As a first example, the glyphs for FULLWIDTH LESS-THAN SIGN (U+FF1C; “<”) and FULLWIDTH GREATER-THAN SIGN (U+FF1E; “>”) in a font with a non-square em-box are transformed into glyphs whose aspect ratio differs from the default glyphs, which are properly sized for sideways presentation in vertical writing mode. As a second example, the glyph for LEFT SQUARE BRACKET (U+005B, “[“) in a brush-script font that exhibits slightly rising horizontal strokes may use an obtuse angle for its upper-left corner when in horizontal writing mode, but an alternate glyph with an acute angle for that corner is supplied for vertical writing mode.

Recommended implementation: The font includes versions of the glyphs covered by this feature that, when rotated 90 degrees clockwise by the layout engine for sideways presentation in vertical writing, differ in some visual way from rotated versions of the default glyphs, such as by shifting or shape. The vrtr feature maps the default glyphs to the corresponding to-be-rotated glyphs (GSUB lookup type 1).

Application interface: For GIDs found in the vrtr coverage table, the layout engine passes GIDs to the feature, then gets back new GIDs.

UI suggestion: This feature should be active by default for sideways runs in vertical writing mode.

Script/language sensitivity: Applies to any script when set in vertical writing mode.

Feature interaction: The vrtr and vert features are intended to be used in conjunction: vrtr for glyphs intended to be presented sideways in vertical writing, and vert for glyphs to be presented upright. Since they must never be activated simultaneously for a given glyph, there should be no interaction between the two features. These features are intended for layout engines that graphically rotate glyphs for sideways runs in vertical writing mode, such as those conforming to UTR#50. (Layout engines that instead depend on the font to supply pre-rotated glyphs for all sideways glyphs should use the vrt2 feature in lieu of vrtr and vert.) Because vrt2 supplies pre-rotated glyphs, the vrtr feature should never be used with vrt2, but may be used in addition to any other feature.

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Some initial Adobe-Japan1-6 versus UTR #50 thoughts…

UTC (Unicode Technical Committee) Meeting #136 took place last week, and one of the significant outcomes was that UTR (Unicode Technical Report) #50 was advanced from Draft to Approved status. Congratulations to Koji ISHII (石井宏治), its editor, and also to Eric Muller, who took the initiative to start this project and served as its first editor.
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The Adobe-Identity-0 ROS & Heuristics

I have advocated the use of the special-purpose and language-neutral Adobe-Identity-0 ROS over the past few years, and have developed several CID-keyed fonts that take advantage of this ROS, but keep in mind that its use can act like a double-edge sword.

On one hand, it provides font developers with great flexibility, in terms of the glyph complement of a font. In other words, font developers need not be restricted to one of our public CJK ROSes, such as Adobe-Japan1-6, or a subset thereof. Kazuraki is an example of a Japanese font whose glyph set requirements didn’t fit Adobe-Japan1-6, so the Adobe-Identity-0 ROS was used.

On the other hand, font developers need to develop all of the necessary resources, such as the UTF-32 CMap Resource that is used as the basis of the ‘cmap‘ table, which maps Unicode code points to glyphs in the font, along with any GSUB features. In addition, and because the Adobe-Identity-0 ROS is language-neutral in that its designation does not specify or suggest a primary language, some applications may incorrectly assign a primary language to such fonts. This, of course, is due to heuristics (発見的教授法 in Japanese), or more specifically, their failure.
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Font Development Via Unicode

Unicode has become the de facto way in which to represent text in digital form, and for good reason: its character set covers the vast majority of the world’s scripts. Other benefits of Unicode include the following:

  • That it is under active and continuous development, meaning that with each new version, more scripts are being supported, and additional characters for existing scripts are being standardized.
  • That it is aligned and kept in sync with ISO/IEC 10646 (available at no charge), which is quite a feat.

With regard to font development, Unicode is considered the default encoding for OpenType, which refers to the ‘cmap‘ table. The most common ‘cmap’ subtables are Formats 4 (BMP-only UTF-16) and 12 (UTF-32). The latter is used only when mappings outside of the BMP (Basic Multilingual Plane), meaning from one or more of the 16 Supplementary Planes, are used.
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「CSS Orientation Test OpenType Fonts」について

[This Japanese version of the May 31, 2013 article entitled CSS Orientation Test OpenType Fonts is courtesy of Hitomi Kudo (工藤仁美).]

五月三十一日にアドビの新しいオープンソースプロジェクトで、「CSS Orientation Test OpenType Fonts」をリリースしたのでお知らせします。このオープンソースプロジェクトは、Unicodeの次期UTR #50(「Unicode Vertical Text Layout」)のエディタである石井宏治氏のリクエストをもとに開発された、二つのOpenType/CFFフォントを含みます。これらフォントの目的は、フォント開発者がより簡単にグリフの方向に関するテストを行えるよう考慮したものです。
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CSS Orientation Test OpenType Fonts

I am pleased to announce that the new CSS Orientation Test OpenType Fonts open source project was launched on Adobe’s open-source portal, Open@Adobe, today. This open source project consists of two OpenType/CFF fonts that were developed at the request of Koji Ishii (石井宏治), the editor of Unicode’s forthcoming UTR #50 (Unicode Vertical Text Layout). The purpose of these fonts is for developers to be able to more easily test whether glyph orientation in their implementation is correct or not.
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OpenType ‘cmap’ Table Ramblings

OpenType fonts are ‘sfnt’ (scalable font) resources that are comprised of several well-defined tables. One of these tables, which is the topic of today’s article, is the ‘cmap‘ (character map) table. The ‘cmap’ table, put simply, maps characters codes to Glyph IDs (GIDs) that refer to glyphs in the ‘glyf‘ or ‘CFF‘ (Compact Font Format) table, depending on the “flavor” of the OpenType font. What is important about the ‘cmap’ table is that it makes the glyphs usable. Without the ability to map from character codes, which are used by virtually all applications and OSes, the glyphs in a font are useless, and cannot be readily accessed or used.
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Gothic/Myungjo or Dotum/Batang?

The prototypical Serif and Sans Serif typeface style distinction in Korean has traditionally used the names Myeongjo (명조체/明朝體 myeongjoche) and Gothic (고딕체/고딕體 godikche), respectively. But, in 1993, the Republic of Korea (South Korea) Ministry of Culture, in an attempt to standardize typographic terms, recommended the use of Batang (바탕 batang) and Dotum (돋움 dotum) as the proper names for these two typeface styles.

At the time the Ministry of Culture recommendation was made, which was a period when printing was the most common use of fonts, Batang was meant for body text, and Dotum was for display or emphasis purposes. Mobile devices have provided a new use for Dotum, because its lack of serifs provided superior readability on mobile devices with smaller screens that necessitated smaller point sizes, and the original rationale for these new names seems to no longer apply.

From what I can tell, Korean type foundries have not embraced the Batang and Dotum names, and have actually resisted their use. What probably didn’t help was the fact that Microsoft released TrueType fonts with these exact names, with no additional qualifiers: Batang and Dotum. In other words, it seems that Microsoft’s use of these names polluted their chance at more widespread use, because they were treated as typeface names, not typeface style names.

In closing this brief article, I am curious about what our blog readership thinks about this particular issue. I welcome any and all comments.

Adobe Blank: Another Adobe-Identity-0 Implementation

As I wrote nearly a year ago, the Adobe-Identity-0 ROS is useful for building special-purpose fonts, especially CJK ones whose glyph coverage does not match one of our public ROSes. Our latest Adobe-Identity-0 ROS font is the open-source Adobe Blank, whose purposes and implementation details are described on our sister blog, Typblography.

Standardized Variants—Part 3

I will close this particular topic by detailing how to support these proposed standardized variants in OpenType/CFF fonts.

For fonts that are currently IVS-enabled, such as those that include Format 14 ‘cmap’ subtables with Adobe-Japan1 or Hanyo-Denshi IVSes, it is important to note that the proposed standardized variants can co-exist with them, at least in terms of being specified in the font. For the former, I created an Adobe-Japan1_sequences.txt file that includes all registered Adobe-Japan1 IVSes, along with 89 of the 1,002 proposed standardized variants. The 89 standardized variants are at the end of the file. AFDKO tools, such as makeotf and spot, already support these standardized variants. When building OpenType/CFF fonts using the makeotf tool, this file is specified as the argument of the “-ci” command-line option.
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Standardized Variants—Part 2

To continue from the December 26, 2012 article, I should first point out that there is a relationship between these 1,002 proposed standardized variants and IVSes (Ideographic Variation Sequences). Standardized variants are standardized, hence their name. IVSes, on the other hand, are registered via a process that is described in UTS #37 and administered by the IVD Registrar (which happens to me at the moment).
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Standardized Variants—Part 1

One problem that has been plaguing CJK Compatibility Ideographs is the fact that they are adversely affected by normalization. Regardless of which of the four normalization forms is applied—NFC, NFD, NFKC, or NFKD—they are converted to their canonical equivalents, which are CJK Unified Ideographs. This is a problem, particularly for Japan, because 75 kanji in JIS X 0213:2004 kanji map to CJK Compatibility Ideograph code points. Furthermore, 57 of these 75 kanji correspond to Jinmei-yō Kanji (人名用漢字), meaning that they are used for personal names. The bottom-line problem with CJK Compatibility Ideographs is that any application of normalization, by any process, will permanently remove any distinctions between a CJK Compatibility Ideograph and its canonical equivalent. Not all processes are under one’s direct control, meaning that it is impossible to guarantee that normalization will not be applied. My opinion is that it is prudent to assume that normalization will be applied, and that preemption is the best solution.
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Old Hangul—Redux

In the December 4, 2012 Old Hangul article I mentioned that the ‘ccmp’ GSUB feature that is referenced in Microsoft’s Developing OpenType Fonts for Korean Hangul Script document is not necessary. Jaemin Chung kindly pointed out to me that environments that do not yet support Unicode Version 5.2 still require the ‘ccmp‘ (Glyph Composition/Decomposition) GSUB feature to be present, otherwise proper shaping will not happen.

The main purpose of this short article is to provide a revised Perl script, named mkoldhangul-ccmp.pl, that adds a complete ‘ccmp’ GSUB feature definition for environments that do not yet support Unicode Version 5.2 (or greater). The sample glyph-map.txt datafile that maps the Unicode-based glyph names to CIDs is unchanged.

Old Hangul

Okay. It is time to put some “K” into CJK…

Seriously, much of the content of this blog has been focused on Chinese and Japanese issues. This article will provide some much-deserved Korean content.

I spent the last few days coming to grips with Old Hangul (옛한글 yethangeul), specifically how to implement proper shaping using the three registered OpenType GSUB features, ‘ljmo‘ (Leading Jamo Forms), ‘vjmo‘ (Vowel Jamo Forms), and ‘tjmo‘ (Trailing Jamo Forms).
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Turning CID-Keyed Fonts Into OpenType Fonts Using AFDKO

日本語/English

10月10日水曜日、香港で開催されたATypI Hong Kong 2012にてAFDKOワークショプをおこないました。とても専門的な内容にもかかわらず、多くの方にご参加いただきありがとうございました。

3時間のワークショプの前半2時間は、Ken Lundeによる「Manipulating CID-Keyed Fonts Using AFDKO Tools」が行われ、後半1時間「Turning CID-Keyed Fonts Into OpenType Fonts Using AFDKO」を私が担当しました。
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Combining 3 Tools Into 1: glyph-list.pl

For those who make use of the extract-cids.pl, extract-gids.pl, or extract-names.pl tools, all of which are AFDKO tx tool filters and are included in AFDKO, and whose purpose is to list the glyphs in the specified font resource, I’d like to introduce a new tool, named glyph-list.pl, which combines their functionality, thus making font development simpler.
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Kazuraki: Under The Hood

I had the opportunity this morning to present at ATypI Hong Kong 2012 about Kazuraki, specifically the details about its OpenType implementation. Hence, the title of the presentation is Kazuraki: Under The Hood. The purpose of this article is simply to make the presentation available.

Manipulating CID-Keyed Fonts Using AFDKO Tools

Yesterday—meaning Wednesday, October 10th, 2012, Hong Kong Time (UTC+8)—I had the honor and privilege to present the first two hours of a three-hour ATypI Hong Kong 2012 workshop entitled Manipulating CID-Keyed Fonts Using AFDKO Tools. When I did a rough count, there were nearly 30 people in attendance. I’d like to use this opportunity to thank those who were able to attend, which meant that they made the effort to travel to this conference, and also chose to attend this workshop in lieu of attending presentations from the Typography & Reading and Typography & Culture tracks, or other concurrent workshops. I’d also like to provide to those who attended, and to those who were not able to attend, the presentation that I used to drive these two hours, which includes material that can be studied and referenced.

In addition to installing the latest-and-greatest version of AFDKO, the workshop attendees were also provide with the actual sample font data that I used to demonstrate the various workflows and techniques.

My hope is that these materials are useful to those who attended this workshop, and to those who were not able to do so. Enjoy!

Speaking of enjoy, that is what I plan to do for the remaining four days of this five-day conference. ☺

AFDKO Workflow Diagrams

One of the most useful bits of feedback that I received from my portion of the June 25, 2012 AFDKO Workshop was that I include workflow diagrams that visually explain how various tools and control files work together. While preparing to present the same material at ATypI Hong Kong 2012 on the afternoon of October 10, 2012, I spent last Friday and this week creating additional presentation slides that include such workflow diagrams.
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Details About The New AFDKO Version…

As I wrote earlier today on our sibling blog, Typblography, a new version of AFDKO was release earlier this month. I want to use this opportunity to point out some of the changes and enhancements that affect font developers who work with CID-keyed fonts. The details are buried in the detailed Release Notes that Read Roberts prepared.
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