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Presentation material for EPUB WG EGLS Taipei Meeting.
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EGLS Requirements EGLS_CG3 In-line Graphics
It should be possible for content providers to embed graphics in text with the intention that the graphics should be aligned, positioned, and sized well with the surrounding text even when the user or reading system selects any writing mode and any font
Rationale: People need something beyond characters or character variations commonly available in the present computing environment, which is typically based on Unicode or ISO/IEC 10646
EGLS_CG4 Font Embedding It should be possible for content providers to embed fonts
such as SVG Fonts and WOFF Fonts as part of EPUB documents
Rationale: Fonts for some characters or character variants might not be always available in any reading system
Solution for Font Embedding EGLS_CG4 Solution A
Use '@font-face' rule specified in CSS Fonts Level 3 to reference Web Fonts (WOFF Fonts, SVG Fonts, or OpenType) embedded within the same EPUB container file
EPUB 2.0 already supports the use of '@font-face' rule specified in CSS Level 2
Using WOFF Fonts is supported on most browsers and appropriate for general font embedding
Issues CSS Level 2 Revision 1 does not specify '@font-face' rule CSS Fonts Level 3 is currently in WD status and may not
become CR status in time for EPUB 3.0 WOFF File Format is currently in WD status and may not
become CR status in time for EPUB 3.0
Web Fonts Implementations WOFF Fonts are going to be supported everywhere
SVG Fonts are currently the only choice for iPhone and iPad
Web BrowserTrueTypeOpenType
EOT WOFF SVG
IE IE9 IE9
Safari WebKit Firefox Opera Chrome
Solution A for In-line Graphics EGLS_CG3 Solution A
Use HTML 'img' element to reference an SVG graphics file or SVG fragment in the same HTML file
This solution also satisfies EGLS_CG4 SVG is a vector graphic format and better than raster image
format like PNG in terms of scalability Using SVG graphics is supported on most browsers and
appropriate for describing small numbers of user defined characters or glyphs
CSS 2D Transforms can be used to rotate SVG graphics to better support mixed text layout
Issues It may be difficult to align SVG graphics with the baseline of
the surrounding text It may be difficult to change SVG graphics based on the font
family used for the surrounding text
SVG In-line Graphics SVG File Example
Use 'path' element todefine a character glyph
Use 'viewBox' attributeto use local coordinatesystem
The path describes aHiragana character " の "
HTML File Example Use 'img' element to
display SVG graphics Referencing an SVG file
from 'img' element isalready supported onmost browsers
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 1000"> <title>IPA Mincho</title> <path fill="black" d="M505 683 Q512 642 512 585 Q512 417 393 225 Q338 137 266 88 Q236 70 214 70 Q178 70 146 107 Q91 169 91 279 Q91 450 218 582 Q348 716 528 716 Q666 716 762 649 Q901 553 901 378 Q901 193 767 98 Q668 27 488 16 L482 41..../></svg>
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Solution A</title> </head>
<body> <div style="font-size:100px;"> なにぬね <img src="IPAMincho.svg" width="100" height="100"> </div> </body></html>
Solution B for In-line Graphics EGLS_CG3 Solution B
Use SVG 'font' element to define graphics as SVG Fonts and put that definition directly into HTML 'head' element. In the same HTML file, we can just specify the 'font-family' for the SVG Font to display the corresponding graphics.
This solution also satisfies EGLS_CG4. SVG Fonts behave just like normal fonts, and the text can be
aligned, selected, and searched very easily.
Issues SVG Fonts may not be supported on some browsers (IE and
Firefox). SVG Fonts don't support hinting and may not be rendered in
highest quality on some display conditions. SVG 1.1 supports both vertical and horizontal layout for SVG
Fonts, but SVG Tiny 1.2 only supports horizontal layout.
SVG Fonts In-line Graphics HTML File Example
Use SVG 'glyph'element to definea character glyph
Use HTML 'span'element to specifythe font family nameof the SVG Font
The use of CSS'@font-face' rule isnot required
Any glyphs withoutcode points can bedefined
<html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Solution B</title> <svg xmlns="http://www.w3.org/2000/svg" width="100" height="100"> <defs> <font horiz-origin-x="0" horiz-adv-x="1000" id="IPAMincho"> <font-face font-family="IPAMincho" units-per-em="1000" ascent="880" descent="120"/> <glyph unicode="の " glyph-name ="の " vert-origin-y="786" vert-adv-y="870" d="M505 683 Q512 642 512 585…"/> </font> </defs> </svg> </head>
<body> <div style="font-size:100px;">なにぬね <span style="font-family:IPAMincho;">の </span> </div> </body></html>
Rendering Quality SVG Fonts Example by John Daggett
people.mozilla.org/~jdaggett/tests/svgfonttest.html
Rendered by Safari on Mac OS X
Effect of Hinting Meiryo Fonts Example by John Daggett
Rendered by Firefox on Windows XP, Windows 7, and Mac OS X, respectively
Appendix
Web Fonts Overview Web Fonts Specification
Introduced in CSS Level 2www.w3.org/TR/2008/REC-CSS2-20080411
Enhanced in CSS Fonts Level 3www.w3.org/TR/2009/WD-css3-fonts-20090618
Major Features Supports downloadable fonts, local fonts, and system fonts Font properties ('font-family', 'font-weight', 'font-stretch',
'font-style', 'font-variant', 'font-size', 'font-size-adjust', 'font') Font reference rules (@font-face, 'src', 'unicode-range') Font matching algorithm
Web Fonts Examples Multi Weights Example
One rule for each weight Use 'local' to use local
fonts if available Use 'url' to reference
downloadable fonts
Composite Font Example One rule for each language
specific font subset file Use "-" to specify range Use "?" for any digit value Download smaller subset
file if the text contains onlyLatin characters
@font-face { font-family: Helvetica; src: local(Helvetica), url(fonts/Helvetica.ttf);}
@font-face { font-family: Helvetica; font-weight: bold; src: local("Helvetica Bold"), url(fonts/HelveticaBold.ttf);}
@font-face { font-family: DroidSans; src: url(DroidSansJp.woff); unicode-range: U+3000-9FFF, U+FF??;}
@font-face { font-family: DroidSans; src: url(DroidSans.woff); unicode-range: U+000-5FF, U+1E00-1FFF, U+2000-2300;}
New in CSS Fonts Level 3 Renewed Font Format List
"truetype", "truetype-aat" : TrueType Font (.ttf) "opentype": OpenType Font (.ttf, .otf) "embedded-opentype": Embedded OpenType Font (.eot) "woff": WOFF Font (.woff) "svg": SVG Font (.svg)
OpenType Features Support Kerning ('font-kerning') and ligatures ('font-variant-ligatures') Subscript and superscript ('character-transform') Alternates and swashes ('font-variant-alternates') Capitalization ('font-variant-caps') Numerical formatting ('font-variant-numeric')
Same-origin Restriction Cross-Origin Resource Sharing (CORS) should be supported as well
WOFF Font Format WOFF Font Specification
WOFF File Format 1.0www.w3.org/TR/2010/WD-WOFF-20100727
WOFF stands for Web Open Font Format
Progress WebFonts Working Group launched in March 2010 W3C Submission from Microsoft, Mozilla, and Opera in April Already implemented on Firefox 3.6, Google Chrome 5, and
IE9 Platform Preview 3
Major Features A GZIP compressed repackaging of TrueType/OpenType fonts Added XML based extended metadata block No DRM (WOFF fonts may not be reused as system fonts) Same-origin restriction as well as CORS is supported
Handling Variations East Asian Text
The editor's draft of CSS Fonts Level 3 introduced 'font-variant-east-asian' property
Supports OpenType Feature Tags (hojo-kanji, jis78, jis83, jis90, jis04, nlckanji, simplified, traditional, fwid, pwid)
OpenType UVS Subtable should be supported as well?
Example of Variations JIS78 Forms (jis78) ■ Traditional Forms (traditional)
Proportionally Spaced Variants (pwid)
SVG Fonts Overview SVG Fonts Specification
Introduced in SVG 1.0www.w3.org/TR/2001/REC-SVG-20010904
Reduced the features in SVG Tiny 1.2www.w3.org/TR/2008/REC-SVGTiny12-20081222
Mandatory feature in SVG 1.1/2.0 (required for ACID3)
Major Features Embedded within HTML/SVG documents or saved as a
separate SVG file (GZIP compressed .svgz file is supported) Define font with 'font' ('horiz-origin-x', 'horiz-adv-x') and 'font-
face' elements ('font-family', 'font-weight', etc.) Define each glyph with 'glyph' element ('unicode', 'glyph-
name', 'd', 'arabic-form', 'lang', 'horiz-adv-x') Hinted outline fonts is not supported
SVG Fonts Examples Inline Font Example
One 'glyph' for each glyph 'd' value contains path data
defining the glyph outline 'unicode' value can be a
character or string (to defineligatures, for example)
External Font Example Font definition can be moved
to local or downloadable files Use 'font-face-uri' to point
to external SVG Font files Need to directly reference
'font' element (by using afragment identifier)
<defs> <font horiz-adv-x="500"> <font-face font-family="Vera" units-per-em="1000"/> <glyph unicode="S" glyph-name="S" d="…"> <glyph unicode="V" glyph-name="V" d="…"> <glyph unicode="G" glyph-name="G" d="…"> <missing-glyph d="…"> </font></defs><text font-family="Vera" font-size="100">SVG</text>
<defs><font> <font-face font-family="Vera"> <font-face-src> <font-face-uri xlink:href="Vera.svg#f"/> </font-face-src> </font-face></font></defs><text font-family="Vera" font-size="100">SVG</text>
New in SVG Tiny 1.2 No Arbitrary SVG
Specify glyph outline only by using path data (with 'd' attribute)
'glyph' element in SVG 1.0/1.1 can contain arbitrary SVG graphic elements)
No Vertical Orientation Unsupported 'font' element attributes: 'horiz-origin-y',
'vert-origin-x', 'vert-origin-y', 'vert-adv-y' Unsupported 'font-face' element attributes: 'v-ideographic', 'v-
alphabetic', 'v-mathematical', 'v-hanging' Unsupported 'glyph' element attributes: 'orientation',
'vert-origin-x', 'vert-origin-y', 'vert-adv-y'
No External Font Descriptors 'definition-src' element is not supported in SVG Tiny 1.2 and
SVG 1.1 2nd Edition
Extending Existing Fonts Extended Font Example
Add @font-face rule foreach user defined character
Use 'unicode-range' tospecify the code point
Default 'unicode-range'value is U+0-10FFFF
Rules defined later takeprecedence
Referencing from HTML Just use the extended font Referencing user defined
characters is easy as log asthe code point is assigned
@font-face { font-family: Helvetica; src: local(Arial);}
@font-face { font-family: Helvetica; src: url(HelveticaEx01.svg#f); unicode-range: U+E758;}
@font-face { font-family: Helvetica; src: url(HelveticaEx02.svg#f); unicode-range: U+E759;}
body { font-family: Helvetica; }
<html> <body> <p>SVG</p> </body></html>
Glyphs without Code Points SVG Glyph Example
Use unique identifier instead of a character asthe value of 'unicode'
SVG user agent recognizesthe specific sequence ofcharacters and replace itwith user defied glyph
Referencing from HTML Use 'image' element to
display a glyph image You can directly embed
an SVG fragment into theHTML5 document
<defs> <font horiz-adv-x="500"> <font-face font-family="Vera" units-per-em="1000"/> <glyph unicode="&edanashi;" glyph-name="edanashi" d="…"> <missing-glyph d="…"> </font></defs><text font-family="Vera" font-size="100">&edanashi;</text>
body { font-family: Vera; }
<html> <body> <p>Edanashi in HTML: <img src="edanashi.svg#f/> </p> <svg> <text>Edanashi in SVG: &edanashi;</text> </svg> </body></html>
