Infogrid Pacific-The Science of Information


Introduction and Overview

Typography in the Browser - An Experimental Feature

Browser Warning

The IGP:Typography in the Browser application extension for IGP:Digital Publisher works with Firefox 4.* only.


Firefox 4 is currently the only browser that supports Open Type Font features, including font kerning. This does not affect other features in IGP:Digital Publisher which will still work on a wide range of standards compliant browsers. Therefore other participants such as editors, proofers and digital format compositors can work with their current preferred browser as long as they do not use it with IGP:Typography in the Browser.

IGP:Typography in the Browser will appear to functionally work with other standards compliant browsers such as Google Chrome, Safari and Opera, but because many of the font properties are Mozilla Firefox 4 specific attributes unsupported by other browsers, the outcome will be unpredictable.

The application DOES NOT CHECK FOR BROWSER version or try to apply any restrictions. It is your responsibility to understand the browser version requirements and limitations of this experimental application features.

IGP:Typography in the Browser is a product where "The Browser is the Application" rather than just a front-end for server processes.

Reason for Experimental Status

The Firefox 4 support of Open Type Font features is custom to Mozilla Firefox pending the ratification of the CSS-3 Fonts Module, which could be more than a year away. Therefore the TIB application interface and behaviour will change because the third-party dependencies will change. Infogrid Pacific makes no warranty on the future of this application interface, but the component files generated will remain in place and useful.

This module only works with standard compliant Open Type Fonts. The reliability or predictability of the application with True Type Fonts or other fonts is not applicable, and is not tested as it is irrelevant. Do not raise any issues about using this application with older fonts. They are irrelevant and will be ignored. It is your responsibility to understand the status and properties of your fonts.

Rendering mismatches

IGP:Typography in the Browser (TIB) attempts to present a WYSIWIG (What You See Is What You Get) view of the document layout as it would be rendered to the final print PDF in much the same way as a DTP application.

There are a number of problems that must be addressed to allow the WYSIWIG goal to be achieved. Firstly the TIB software does not have any control of, or access to, the PDF or Browser layout engines. The PDF is optimized for print, the browser optimized for on-screen web content display.

It is virtually impossible to match two layout engines from different sources, and even more difficult when they render to two different surfaces with different resolutions. The engines are going to do things differently.

Hyphenation. Both the hyphenation feature in the browser and the PrinceXML PDF rendering engine use the same TeX hyphenation algorithm. However the browser version does not limit the number of consecutive hyphenated lines and due to microspacing differences may hyphenate at different points.

Widows and Orphans. There is no way to currently display various and different widow and orphan settings.

While the browser engine does have sub-pixel rendering, this does not alter the fact that the layout is on a 96dpi integer layout screen surface, vs. a floating-point independently rendered surface for EPS/PDF.

The official internet resolution is 96dpi (not 72dpi) and is supported by all browsers. Firefox came into alignment with all other browsers in this matter in Version 4. The standard states that all physical units must be converted to 96dpi. Therefore a point (1/72in) becomes 1.33 pixels (96/72). A 12 point font is 16px. 

Firefox supports all OTF properties that an OTF font has. The most important of these is font kerning, which can significantly affect the flow of text when hypenation is applied.

To match the two rendering engines calibration adjustments to fine-tune the primary layout metrics differences must be made. These are the font size, galley width, word spacing and letter spacing. 

Please carefully read the Calibrating TIB document carefully to understand how it all works and to get the maximum productivity and value from the application extension. 
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