The Problem to Solve

The recent proliferation of web browsers and computer networks has made it easy to display the same document on different computing platforms. However, inconsistencies in the way fonts are rendered across different computing platforms could cause the same document to be rendered differently for users of different computing platforms. More specifically, for a given font, the way in which metrics for various font features are interpreted, such as character height, width, leading and white space, can differ between computing platforms. These differences in interpretation could cause individual characters in a document to be rendered at different locations, which could ultimately cause the words in a document to be positioned differently between lines and pages on different computing platforms.

This inconsistent rendering could be a problem for people who are collaborating on a document. For example, if one collaborator points out an error on a specific line of a specific page, another collaborator viewing the same document on a different computing platform may have to first locate the error on a different line of a different page.

Hence, what is needed is a technique for providing consistent rendering for documents across different computer systems and computing platforms.

Apple's Solution

Some embodiments presented in Apple's patent application describe a system that typesets and renders a document in a platform-independent manner. During operation, the system first obtains the document, wherein the document includes text content and associated style information including one or more fonts. The system also generates platform-independent font metrics for the one or more fonts, wherein the platform-independent font metrics include information that could be used to determine the positions of individual characters in a rendering of the document. Next, the system uses the platform-independent font metrics to determine how the document is divided into line fragments and pages. Finally, the system uses the determined division while rendering the document, so that the division of the document into line fragments and pages is the same across different computing platforms.

In some embodiments, the system operates within a platform-independent word-processing application that operates within a web browser.

In some embodiments, the system operates within a web browser.

In some embodiments, while using the platform-independent font metrics to determine how the document is divided into line fragments and pages, the system determines the locations of individual characters within the line fragments in the rendering of the document.

In some embodiments, rendering the document involves performing a high-fidelity rendering, which uses the determined division of the document into line fragments and pages and renders individual characters at the determined locations within the line fragments.

In some embodiments, rendering the document involves performing a lower-fidelity rendering, which uses the determined division of the document into line fragments and pages. However, unlike the high-fidelity rendering, this lower-fidelity rendering does not use the determined locations for the individual characters, but instead allows the renderer to use platform-specific rendering mechanisms to determine the locations of the individual characters within the line fragments.

In some embodiments, rendering the document involves first generating code in a platform-independent markup language, which specifies the rendering for the document, and then executing the generated code to render the document.

In some embodiments, rendering the document involves rendering only a visible portion of the document.

Apple Describes a Platform Independent Word Processor for Browsers

Apple establishes their platform independent word processor methodically starting with the client system (106) which hosts a web browser (114). The browser could generally include any program that is capable of displaying web pages containing code specified in a platform-independent markup language.

In the embodiment illustrated in patent FIG. 1, the browser hosts a platform-independent word processor (116) which enables the user to edit a document. While displaying a document, the platform-independent word processor ensures that the document is divided into line fragments and pages in the same way across different computing platforms.

A Word Processor or Other Apps could be Cross Platform, Period

Apple states that although the present invention is primarily described in the context of a browser-based word processing system, the present invention could in fact be more generally applied to any system that renders textual information in a platform-independent manner and is not meant to be limited to word-processing systems or browser-based systems.

Flow Charts Associated with Apple's Browser-Based Application

Apple's patent FIG. 4 presents a flow chart illustrating how a browser-based application executes in accordance with an embodiment of the present invention; Apple's patent FIG. 5 presents a flow chart illustrating how the platform-independent font metrics are used to determine how a document will be divided into line fragments and pages.

Apple credits Christopher Rudolph, Boris Prokofiev and Mark Ambachtsheer as the inventors of patent application 20110119573, originally filed in Q4 2009.

Update

I'm adding a view point that I made earlier as a comment below for clarification. The "breakthrough" is that Apple will be introducing apps beyond Safari and iTunes that could run on PC's and maybe other platforms. Many PC users have wanted access to some of Apple's other iApps and this is a sign that Apple is considering it. In that light and context, it's certainly a breakthrough.

Microsoft had tablets out first and Sony had an MP3 player out first but it was Apple which made these devices the hits that they are today. I understand that some in the PC community can't stand Apple's breakthroughs but I thought by now that they'd be used to it. I guessed wrong. Also check out a comment presented below that came in from Ken who makes several outstanding points about Apple's breakthrough.

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