DOCSLIB.ORG

Interactive Keys to Enhance Gaze-Based Typing Experience

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Interactive Keys to Enhance Gaze-Based Typing Experience GazeTheKey: Interactive Keys to Integrate Word Predictions for Gaze-based Text Entry Korok Sengupta Raphael Menges Abstract Institute for Web Science Institute for Web Science In the conventional keyboard interfaces for eye typing, the and Technologies (WeST) and Technologies (WeST) functionalities of the virtual keys are static, i.e., user’s gaze University of Koblenz-Landau University of Koblenz-Landau at a particular key simply translates the associated letter Koblenz, Germany Koblenz, Germany [email protected] [email protected] as user’s input. In this work we argue the keys to be more dynamic and embed intelligent predictions to support gaze- based text entry. In this regard, we demonstrate a novel "GazeTheKey" interface where a key not only signifies the Chandan Kumar Steffen Staab input character, but also predict the relevant words that Institute for Web Science Institute for Web Science and Technologies (WeST) and Technologies (WeST) could be selected by user’s gaze utilizing a two-step dwell University of Koblenz-Landau University of Koblenz-Landau time. Koblenz, Germany Koblenz, Germany [email protected] Web and Internet Science Author Keywords Research Group, University of Gaze input; eye tracking; text entry; eye typing; dwell time; Southampton, UK visual feedback. [email protected] ACM Classification Keywords H.5.2 [Information interfaces and presentation]: User Inter- faces Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed Introduction for profit or commercial advantage and that copies bear this notice and the full citation Gaze-based text entry is a valuable mechanism for the on the first page. Copyrights for third-party components of this work must be honored. For all other uses, contact the Owner/Author. people with severe motor disabilities, who have no or lit- Copyright is held by the owner/author(s). tle control of muscles to operate the physical keyboard. IUI’17 Companion, March 13-16, 2017, Limassol, Cyprus. ACM 978-1-4503-4893-5/17/03. Usually, eye typing is accomplished by onscreen keyboard, DOI: http://dx.doi.org/10.1145/3030024.3038259 where the user selects the letters by looking at them for certain duration called dwell time [4]. Researchers have proposed alternate designs like Dasher [8], or dwell-free Fil- representation basically relies on the next word that the re- teryedping [7] to achieve high performance, which needs spective language model could predict based on the previ- extensive training and expertise for faster and accurate ously entered text by user [9]. Figure1 shows the represen- input. Therefore, to assist novice users, most of the com- tation sketch of the keys containing the letter and the as- mercial and popular gaze-based systems1 follow the con- sociated word suggestion at the bottom. The green framed vectional design of QUERTY key layout, associated with letters on the key are the ones that have been already en- text area and word predictions. In the context, word pre- tered by user. This is succeeded by the letter on the key, dictions becomes a significant aspect, since it can reduce framed in yellow. The red frame signifies the suggestive the number of keystrokes required to write the word and letters predicted based on previous letters. decrease user’s effort while typing. However, for eye typ- ing there is an additional cost of perceptual and cognitive While Figure1 presents the structure of word suggestion load, caused by shifting the focus from the keyboard layout on keys, Figure 2 displays the user interaction methodology to the suggested word list and the repeated scanning of the via different states of a key on eye gaze fixation. a) At first, list. Moreover, users are overloaded by the task of typing the key is in its standard mode to trigger the input of the and might overlook the suggestions from an external area single letter displayed on it. b) This is implemented via a as they are engaged in the visual search task of finding the dwell time that is visualized through an orange circle. When next key to enter the intended letter. Hence, there is a need the user’s gaze is upon the key, the circle grows from the to bring the predicted words within the visual search area of center of the key until the key’s area is completely filled. c) users. Furthermore, in the conventional design the word list The input of the displayed letter is triggered and a visual is typically limited to three or four words, due to the space feedback in appearance of a black pulse as feedback to limitation of eye controlled interfaces [2], e.g., large buttons the user. d) If a suggestion is available by the prediction to tackle eye tracking accuracy. engine, the key now turns into suggestion mode e) Further gaze fixation by the user lets the area of the suggestion fill In this work, we move beyond the conventional design of the key starting from bottom and ending at the top. f) When text suggestions as few predicted words on the top of key- the key is filled after this second dwell time, the currently board layout, and propose a dynamic approach of embed- collected word is replaced by the given suggestion. All key ding the suggestions on the key, which would not only bring actions can be aborted by the user by looking at a different Figure 1: Suggestion per key is the relevant suggestions in the visual attention of users, it position on the screen. estimated with previous letters would also offer the possibility to include much more sug- entered by user, and letter gestions. Figure 3 shows the complete design of GTK keyboard in- associated with the key as input. In terface including above-mentioned functionality (detailed the image above the already GazeTheKey demonstration of GTK usage is available here2). The de- collected part of the word is framed The two major component of GazeTheKey (GTK) design sign includes the principles of eye-controlled interfaces [2] green, the letter on the key as (e.g., enlarged buttons and visual feedback to cope with eye yellow, and the suggestive part by is: how does the keys represent the word suggestions, and prediction engine red. how does the user interact with these suggestions. The 1https://github.com/OptiKey/OptiKey/wiki 2https://www.youtube.com/watch?v=-UDDTJHBPVA tracking accuracy), moreover, it follows the usability heuris- tics of Neilsen [6], keeping the design as close to conven- tional keyboard layout as possible with minor adjustment of key formation and addition of necessary keys for improving efficiency while typing. (a) Standard mode. In the shown example in Figure 3, user typed some letter of a word and the current state of all keys shows relevant suggestions that can be selected via additional dwell time over the key (as explained in Figure 2). One limitation of such a two-step dwell time input is that the user wouldn’t First dwell time. (b) be able to dwell on a letter consecutively to type the letter multiple times. Hence an extra repeat key has been added Figure 3: The new keyboard with characters predicting the next at the lower bottom of the environment. This key serves the possible word if character were chosen. The repeat key on the left purpose to trigger the input of the last selected letter. We bottom row repeats the previously typed in letter. have done some further optimization to minimize the visual search for users, i.e., space and backspace key is used to (c) Letter input. present further information about the currently edited word. ployed. The dictionary of the prediction engine is composed As shown in the example, the space button works as the of a random subset of 50.000 English sentences from the 5 confirmation of the typed word and therefore it is displayed Tatoeba database. The proposed design presents several on the bottom of key. A preview of the edited word (after word predictions as one suggestion per key is to be com- deletion by backspace) is displayed on the backspace key puted. Therefore, an asynchronous calculation has been (d) Suggestion mode. (essentially showing the usage of respected key). These set up to guarantee an interruption-free interaction, other- simple heuristics help the user to stay with the gaze on the wise the rendering may freeze after letter input for some same position without the need to check the intended action seconds and user’s gaze would have no effect on the inter- on the edited word. face. Implementation Evaluation (e) Second dwell time. The proposed keyboard has been developed as experi- We have conducted an initial small-scale study with SMI mental eyeGUI [5] element in C++. eyeGUI is a graphical REDn remote eye tracker to investigate how the proposed user interface framework for eye tracking driven applica- design is able to support the task of eye typing. Ten partici- tions. Rendering is handled by OpenGL function calls and pants (5 male, 5 female) contributed in our study, they were the FreeType23 library is used for font rasterization. For the aged between 21 and 30 years (mean 24.8, SD 2.347) and relevant word predictions, Presage4 library has been em- had no prior experience with eye controlled interfaces. We (f) Suggestion input. asked the participants to type 25 different sentences (in five 3http://www.freetype.org Figure 2: Key interactions. 4http://presage.sourceforge.net 5https://tatoeba.org/eng sessions), which were randomly chosen from the phrase 2. C. Kumar, R.
Load more

Recommended publications
  • Performance Analysis of Text-Oriented Printing Using Postscript
    Rochester Institute of Technology RIT Scholar Works Theses 1988 Performance analysis of text-oriented printing using PostScript Thomas Kowalczyk Follow this and additional works at: https://scholarworks.rit.edu/theses Recommended Citation Kowalczyk, Thomas, "Performance analysis of text-oriented printing using PostScript" (1988). Thesis. Rochester Institute of Technology. Accessed from This Thesis is brought to you for free and open access by RIT Scholar Works. It has been accepted for inclusion in Theses by an authorized administrator of RIT Scholar Works. For more information, please contact [email protected]. Rochester Institute ofTechnology School ofComputer Science and Technology Perfonnance Analysis of Text-Oriented Printing Using POSTSCRIPT® by Thomas L. Kowalczyk A thesis, submitted to The Faculty ofthe School ofComputer Science and Technology, in partial fulfillment ofthe requirements for the degree of Master ofScience in Computer Science Approved by: Guy Johnson Professor and Chairman of Applied Computer Studies Dr. Vishwas G. Abhyankar instructor Frank R.Hubbell instructor October 10, 1988 Thesis Title: Performance Analysis of Text-Oriented Printing Using POSTSCRIPT® I, Thomas L. Kowalczyk, hereby grant permission to the Wallace Memorial Libra.ry, of R.I.T., to reproduce my thesis in whole or in part under the following conditions: 1. I am contacted each time a reproduction is made. I can be reached at the fol1mving address: 82 Brush Hollow Road Rochester, New York 14626 Phone # (716) 225-8569 2. Any reproduction will not be for commercial use orprofit. Date: October 10,1988 i Pennission Statement Apple, Appletalk, LaserWriter, and Macintosh are registered trademarks of Apple Computer, Inc. Fluent Laser Fonts and Galileo Roman are trademarks of CasadyWare Inc.
    [Show full text]
  • Institutionen För Datavetenskap Department of Computer and Information Science
    Institutionen för datavetenskap Department of Computer and Information Science Final thesis GPU accelerated rendering of vector based maps on iOS by Jonas Bromö and Alexander Qvick Faxå LIU-IDA/LITH-EX-A--14/023--SE 2014-05-30 Linköpings universitet Linköpings universitet SE-581 83 Linköping, Sweden 581 83 Linköping Linköpings universitet Institutionen för datavetenskap Final thesis GPU accelerated rendering of vector based maps on iOS by Jonas Bromö and Alexander Qvick Faxå LIU-IDA/LITH-EX-A--14/023--SE 2014-05-30 Supervisor: Anders Fröberg (IDA), Thibault Durand (IT-Bolaget Per & Per AB) Examiner: Erik Berglund Abstract Digital maps can be represented as either raster (bitmap images) or vector data. Vector maps are often preferable as they can be stored more efficiently and rendered irrespective of screen resolution. Vector map rendering on demand can be a computationally intensive task and has to be implemented in an efficient manner to ensure good performance and a satisfied end-user, especially on mobile devices with limited computational resources. This thesis discusses different ways of utilizing the on-chip GPU to improve the vector map rendering performance of an existing iOS app. It describes an implementation that uses OpenGL ES 2.0 to achieve the same end-result as the old CPU-based implementation using the same underlying map infras- tructure. By using the OpenGL based map renderer as well as implementing other performance optimizations, the authors were able to achieve an almost fivefold increase in rendering performance on an iPad Air. i Glossary AGG Anti-Grain Geometry. Open source graphics library with a software renderer that supports Anti-Aliasing and Subpixel Accuracy.
    [Show full text]
  • Adobe Type 1 Font Format Adobe Systems Incorporated
    Type 1 Specifications 6/21/90 final front.legal.doc Adobe Type 1 Font Format Adobe Systems Incorporated Addison-Wesley Publishing Company, Inc. Reading, Massachusetts • Menlo Park, California • New York Don Mills, Ontario • Wokingham, England • Amsterdam Bonn • Sydney • Singapore • Tokyo • Madrid • San Juan Library of Congress Cataloging-in-Publication Data Adobe type 1 font format / Adobe Systems Incorporated. p. cm Includes index ISBN 0-201-57044-0 1. PostScript (Computer program language) 2. Adobe Type 1 font (Computer program) I. Adobe Systems. QA76.73.P67A36 1990 686.2’2544536—dc20 90-42516 Copyright © 1990 Adobe Systems Incorporated. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Adobe Systems Incorporated and Addison-Wesley, Inc. Printed in the United States of America. Published simultaneously in Canada. The information in this book is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by Adobe Systems Incorporated. Adobe Systems Incorporated assumes no responsibility or liability for any errors or inaccuracies that may appear in this book. The software described in this book is furnished under license and may only be used or copied in accordance with the terms of such license. Please remember that existing font software programs that you may desire to access as a result of information described in this book may be protected under copyright law. The unauthorized use or modification of any existing font software program could be a violation of the rights of the author.
    [Show full text]
  • Higher Quality 2D Text Rendering
    Journal of Computer Graphics Techniques Vol. 2, No. 1, 2013 Higher Quality 2D Text Rendering http://jcgt.org Higher Quality 2D Text Rendering Nicolas P. Rougier INRIA No hinting Native hinting Auto hinting Vertical hinting Figure 1. When displaying text on low-resolution devices (DPI < 150), one typically has to decide if one wants to respect the pixel grid (e.g., Cleartype technology / Microsoft / native hinting) for crisp rendering or, to privilege glyph shapes (Quartz technology / Apple / no hinting) at the cost of blurring. There is, however, a third way that may combine the best of the two technologies (vertical hinting). Abstract Even though text is pervasive in most 3D applications, there is surprisingly no native sup- port for text rendering in OpenGL. To cope with this absence, Mark Kilgard introduced the use of texture fonts [Kilgard 1997]. This technique is well known and widely used and en- sures both good performances and a decent quality in most situations. However, the quality may degrade strongly in orthographic mode (screen space) due to pixelation effects at large sizes and to legibility problems at small sizes due to incorrect hinting and positioning of glyphs. In this paper, we consider font-texture rendering to develop methods to ensure the highest quality in orthographic mode. The method used allows for both the accurate render- ing and positioning of any glyph on the screen. While the method is compatible with complex shaping and/or layout (e.g., the Arabic alphabet), these specific cases are not studied in this article. 50 Journal of Computer Graphics Techniques Vol.
    [Show full text]
  • Classification of Digital Typefaces Using Spectral Signatures
    Pattern Recognition, Vol. 25, No. 8, pp. 869 876, 1992 0031 3203/92 $5.00+.00 Printed in Great Britain Pergamon Press Ltd © 1992 Pattern Recognition Society CLASSIFICATION OF DIGITAL TYPEFACES USING SPECTRAL SIGNATURES ROBERT A. MORRIS Department of Mathematics and Computer Science, University of Massachusetts at Boston, Boston, MA 02125-3393, U.S.A. (Received 18 April 1991; in revisedform 20 November 199 l; receivedfor publication 11 December 1991) Abstract--Mean Fourier amplitudes through a bank of bandpass filters provide a feature vector with which typefaces can be identified using a piecewise quadratic classifier. Fourier amplitudes Typefaceclassification Quadratic classifier Digital type Digital fonts I. INTRODUCTION grapher. These professionals have various informal classification schemes for their choices--some tradi- In this paper we describe the results of classification tional and widely used, others personal and unarticu- experiments we have performed on text images in lated. Attempts at such classifications and character- various digital fonts. The feature vectors in the study izations by these professionals and those who design are derived from data in the Fourier amplitude spectra the letterforms are the subject of substantial critical of the images. These experiments have several purposes: writing, especially of individual typeface designs, ~4'5) (a) to establish statistical verification of certain predic- but there have been only the simplest statistical studies tions made by image processing theory; (b) to provide of
    [Show full text]
  • Variable Fonts in Chrome Webengines Hackfest, Igalia, a Coruña
    Variable Fonts in Chrome Webengines Hackfest, Igalia, A Coruña Behdad Esfahbod [email protected] Dominik Röttsches [email protected] Demos ● Responsive Web Typography ● Font Playground ● Underware’s HOI Variable Fonts in CSS Level 4 Fonts font-weight, font-stretch, font-style before font-weight, font-stretch, font-style variable Ranges in @font-face @font-face { font-family: Roboto; font-weight: 700; /* or: 400, 600, 900,... */ font-style: normal; /* or: italic, oblique */ font-stretch: condensed; /* or: expanded, ultra-expanded */ } Ranges in @font-face @font-face { font-family: Roboto; font-weight: 400 700; font-style: 10deg 20deg; font-stretch: 50% 200%; } New Font Style Matching Algorithm ● https://drafts.csswg.org/css-fonts-4/#font-style-matching ● Previously, for a font request: ○ Match font-stretch, font-style, font-weight by traversing keyword values, find closest keyword ● New definition: Search for numerically nearest value ○ As defined by @font-face and ○ Within the range that the variable font allows font-optical-sizing font-variation-settings ● Similar to font-feature-settings ● Sequence of 4 character axis name plus font-variation-settings: ‘wght’ 700, ‘UPWD’ 200; Variable Fonts in Blink New CSS Font Matching Algorithm ● Implements font-stretch, font-style, font-weight matching based on numbers, not based on keywords ● FontTraits replaced with FontSelectionRequest ○ Now storing three FontSelectionValues (numerical values for stretch, style weight) ● FontSelectionCapabilities are storing what the @font-face definition provides
    [Show full text]
  • Locale Database
    International Language Environments Guide Part No: 817–2521–11 November 2010 Copyright © 2005, 2010, Oracle and/or its affiliates. All rights reserved. This software and related documentation are provided under a license agreement containing restrictions on use and disclosure and are protected by intellectual property laws. Except as expressly permitted in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast, modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for interoperability, is prohibited. The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing. If this is software or related software documentation that is delivered to the U.S. Government or anyone licensing it on behalf of the U.S. Government, the following notice is applicable: U.S. GOVERNMENT RIGHTS Programs, software, databases, and related documentation and technical data delivered to U.S. Government customers are “commercial computer software” or “commercial technical data” pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. As such, the use, duplication, disclosure, modification, and adaptation shall be subject to the restrictions and license terms setforth in the applicable Government contract, and, to the extent applicable by the terms of the Government contract, the additional rights set forth in FAR 52.227-19, Commercial Computer Software License (December 2007). Oracle America, Inc., 500 Oracle Parkway, Redwood City, CA 94065.
    [Show full text]
  • Font Hinting Techniques and the Importance of Applying These Techniques for High-Quality Display of Fonts on the Output Device Screen
    Faculty of Technical Sciences - Graphic Engineering and Design Preliminary report UDK: 655.24:655.262 Font hinting techniques and the importance of applying these techniques for high-quality display of fonts on the output device screen Banjanin Bojan1, Nedeljkovic Uroš1 1University of Novi Sad, Faculty of Technical Sciences, Department of Graphic engineering and design, Trg Dositeja Obradovica 6, 21000 Novi Sad, Serbia, Corresponding author: Banjanin Bojan Email: [email protected] Abstract: In the era of contemporary and rapid way of life and with advancing digital technology, the display of electronic content on different types of portable devices becomes a part of everyday life. Whether it is on the screen of a Tab- let PC, mobile phone or e-book reader, the font needs to be designed in such a way that the displayed message is received and understood as easy and efficiently as possible. When it comes to digital font, intended for display on screen, it is necessary to take into account the properties of the output device and font size to be used. Since the text is intended for display on small screens (especially in case of portable devices), the used font should be adapted to such conditions, namely, it should be designed so as to be readable and legible even at small sizes and at different resolutions of the device. The integral part of contemporary outline fonts are additional instructions on how rasterizer is to render letters at lower resolutions and lower font sizes. These instructions are known as hints, or hint mechanisms, and the process of defining these instructions is called hinting.
    [Show full text]
  • Learning a Stroke-Based Representation for Fonts
    Volume 0 (1981), Number 0 pp. 1–13 COMPUTER GRAPHICS forum Learning A Stroke-Based Representation for Fonts Elena Balashova1, Amit H. Bermano1, Vladimir G. Kim2, Stephen DiVerdi2, Aaron Hertzmann2, Thomas Funkhouser1 1Princeton University 2Adobe Research Examples: Consistency: Manifold Learning: Retrieval: ] Completion: Interpolation: Figure 1: We learn style variations from existing typeface collections by representing them using a consistent parameterization, and projecting onto a low dimensional manifold. We start with a set of glyph examples that are not consistently parameterized, and use our fitting method to produce a part-based template parametrization consistent across same glyphs. We project the parametrization features into a low dimensional manifold and thus produce a missing-data-aware generative model. The resulting manifold can be used for exploratory applications to understand collections of fonts: topology-aware font retrieval, completion, and interpolation. Abstract Designing fonts and typefaces is a difficult process for both beginner and expert typographers. Existing workflows require the designer to create every glyph, while adhering to many loosely defined design suggestions to achieve an aesthetically appealing and coherent character set. This process can be significantly simplified by exploiting the similar structure character glyphs present across different fonts and the shared stylistic elements within the same font. To capture these correlations we propose learning a stroke-based font representation from a collection of existing typefaces. To enable this, we develop a stroke-based geometric model for glyphs, a fitting procedure to re-parametrize arbitrary fonts to our representation. We demonstrate the effectiveness of our model through a manifold learning technique that estimates a low- dimensional font space.
    [Show full text]
  • Adobe Type 1 Font Format Adobe Systems Incorporated
    Type 1 Specifications 6/21/90 final front.legal.doc Adobe Type 1 Font Format Adobe Systems Incorporated Addison-Wesley Publishing Company, Inc. Reading, Massachusetts x Menlo Park, California x New York Don Mills, Ontario x Wokingham, England x Amsterdam Bonn x Sydney x Singapore x Tokyo x Madrid x San Juan Library of Congress Cataloging-in-Publication Data Adobe type 1 font format / Adobe Systems Incorporated. p. cm Includes index ISBN 0-201-57044-0 1. PostScript (Computer program language) 2. Adobe Type 1 font (Computer program) I. Adobe Systems. QA76.73.P67A36 1990 686.2’2544536—dc20 90-42516 Copyright © 1990 Adobe Systems Incorporated. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Adobe Systems Incorporated and Addison-Wesley, Inc. Printed in the United States of America. Published simultaneously in Canada. The information in this book is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by Adobe Systems Incorporated. Adobe Systems Incorporated assumes no responsibility or liability for any errors or inaccuracies that may appear in this book. The software described in this book is furnished under license and may only be used or copied in accordance with the terms of such license. Please remember that existing font software programs that you may desire to access as a result of information described in this book may be protected under copyright law.
    [Show full text]
  • Pixelating Vector Line Art
    Pixelating Vector Line Art Tiffany C. Inglis (Advisor: Craig S. Kaplan) University of Waterloo Abstract Rasterization is a widely studied problem that forms part of the foundation of computer graphics. Numerous algorithms have been Pixel artists rasterize vector paths by hand to minimize artifacts at developed in the past few decades, with an emphasis of improving low resolutions and emphasize the aesthetics of visible pixels. We efficiency. All these rasterization algorithms assume pixels to be describe Superpixelator, an algorithm that automates this process small enough to produce a continuous signal that can be processed by rasterizing vector line art in a low-resolution pixel art style. Our seamlessly by the human visual system. However, the assumption method successfully eliminates most rasterization artifacts in order that pixels are infinitesimal is not true and often we encounter lim- to draw smoother curves, and an optimization-based approach is itations on the pixel level. In typography, for example, fonts are used to preserve various path properties. A user study compares frequently rendered as pixel-thin paths. Na¨ıvely applying rasteri- our algorithm to commercial software and human subjects for its zation to font outlines will introduce various artifacts, drastically ability to rasterize effectively at low resolutions. A professional reducing readability (compare the text renderings in Figure2). pixel artist reports our results as on par with hand-drawn pixel art. Pixel art is another area in which pixel placement is extremely im- 1 Problem and Motivation portant and current rasterization algorithms cannot replace human effort adequately (see the image comparison in Figure2). Pixel art Digital images are represented in one of two ways: as raster graph- is a style of digital art created and edited on the pixel level.
    [Show full text]
  • The Xft Font Library: Architecture and Users Guide
    The Xft Font Library: Architecture and Users Guide Keith Packard XFree86 Core Team, SuSE Inc. [email protected] Abstract file access and rasterization, a new library was needed to perform this task on the client side of the wire. As the Render extension was designed to support anti-aliased The X Render Extension provides a new glyph rendering graphics, this new library needed to provide support for architecture based on client-side glyph and font manage- high-quality anti-aliased glyph rasterization. ment. While this resolves many tough technical issues relating to the extension design, it places the burden of The FreeType project[TT00] has developed a complete rasterizing, configuring and customizing font usage on font rasterization engine for most outline font formats every X client. along with standard X PCF bitmap fonts. The Render extension takes glyph images and presents them on the The Xft library was written to provide X applications screen. All that was needed was a thin layer of glue a convenient interface to the FreeType font rasterizer code to fit between FreeType and the Render extension and the Render extension. As FreeType provides for no to enable applications to present high-quality text on the configuration or customization, Xft also performs this screen. task. Xft provides new font naming conventions, so- phisticated font matching and selection mechanisms and For X servers not supporting the Render extension, the sufficient abstrations to permit common applications to library should provide access to “core” fonts (fonts ac- benefit from Render extension based text output while cessed through the original core X protocol).
    [Show full text]