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diff --git a/doc/src/emb-fonts.qdoc b/doc/src/emb-fonts.qdoc new file mode 100644 index 0000000..3ed23c3 --- /dev/null +++ b/doc/src/emb-fonts.qdoc @@ -0,0 +1,201 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Qt Software Information (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at qt-sales@nokia.com. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \page qt-embedded-fonts.html + + \title Qt for Embedded Linux Fonts + \ingroup qt-embedded-linux + + \l {Qt for Embedded Linux} uses the + \l{http://freetype.sourceforge.net/freetype2/index.html}{FreeType 2} + font engine to produce font output. The formats supported depends on + the locally installed version of the FreeType library. In addition, + \l{Qt for Embedded Linux} supports the Qt Prerendered Font formats (\l QPF and \l QPF2): + light-weight non-scalable font formats specific to \l {Qt for Embedded Linux}. + QPF2 is the native format of \l{Qt for Embedded Linux}. QPF is the legacy + format used by Qt/Embedded 2.x and 3.x. Several of the formats may be rendered + using anti-aliasing for improved readability. + + When \l{Qt for Embedded Linux} applications run, they look for fonts in + Qt's \c lib/fonts/ directory. \l {Qt for Embedded Linux} will automatically detect + prerendered fonts and TrueType fonts. For compatibility, it will also read the + legacy \c lib/fonts/fontdir file. + + Support for other font formats can be added, contact + \l{mailto:qt-info@nokia.com}{qt-info@nokia.com} for more + information. + + \tableofcontents + + \table 100% + \row + \o + \bold {Optimization} + + The \l FreeType, \l QPF2 and \l QPF formats are features that can be + disabled using the + \l{Fine-Tuning Features in Qt}{feature definition system}, + reducing the size of Qt and saving resources. + + Note that at least one font format must be defined. + + See the \l {Fine-Tuning Features in Qt} documentation for + details. + + \o + \inlineimage qt-embedded-fontfeatures.png + \endtable + + All supported fonts use the Unicode character encoding. Most fonts + available today do, but they usually don't contain \e all the + Unicode characters. A complete 16-point Unicode font uses over 1 + MB of memory. + + \target FreeType + \section1 FreeType Formats + + The \l {http://freetype.sourceforge.net/freetype2/index.html}{FreeType 2} + library (and therefore \l{Qt for Embedded Linux}) can support the following font formats: + + \list + \o TrueType (TTF) + \o PostScript Type1 (PFA/PFB) + \o Bitmap Distribution Format (BDF) + \o CID-keyed Type1 + \o Compact Font Format (CFF) + \o OpenType fonts + \o SFNT-based bitmap fonts + \o Portable Compiled Format (PCF) + \o Microsoft Windows Font File Format (Windows FNT) + \o Portable Font Resource (PFR) + \o Type 42 (limited support) + \endlist + + It is possible to add modules to the \l + {http://freetype.sourceforge.net/freetype2/index.html}{FreeType 2} + font engine to support other types of font files. For more + information, see the font engine's own website: \l + http://freetype.sourceforge.net/freetype2/index.html. + + Glyphs rendered using FreeType are shared efficiently between applications, + reducing memory requirements and speeding up text rendering. + + \omit + \l {Qt for Embedded Linux} will by default use the system FreeType library if it exists. + Otherwise it will use a copy of the FreeType library in Qt, which by default only + supports TrueType fonts to reduce footprint. + \endomit + + \target QPF2 + \section1 Qt Prerendered Font (QPF2) + + The Qt Prerendered Font (QPF2) is an architecture-independent, + light-weight and non-scalable font format specific to \l{Qt for Embedded Linux}. + + Nokia provides the cross-platform \c makeqpf tool, included in the + \c tools directory of both \l {Qt} and \l{Qt for Embedded Linux}, which allows + generation of QPF2 files from system fonts. + + QPF2 supports anti-aliasing and complex writing systems, using information + from the corresponding TrueType font, if present on the system. The format + is designed to be mapped directly to memory. The same format is used to + share glyphs from non-prerendered fonts between applications. + + \target QPF + \section1 Legacy Qt Prerendered Font (QPF) + + Nokia provides support for the legacy QPF format for compatibility + reasons. QPF is based on the internal font engine data structure of Qt/Embedded + versions 2 and 3. + + Note that the file name describes the font, for example \c helvetica_120_50.qpf + is 12 point Helvetica while \c helvetica_120_50i.qpf is 12 point Helvetica \e italic. + + \omit + \section1 Memory Requirements + + Taking advantage of the way the QPF format is structured, Qt for + Embedded Linux memory-maps the data rather than reading and parsing it. + This reduces RAM consumption even further. + + Scalable fonts use a larger amount of memory per font, but + these fonts provide a memory saving if many different sizes of each + font are needed. + \endomit + + \section1 The Legacy \c fontdir File + + For compatibility reasons \l{Qt for Embedded Linux} supports the \c fontdir + file, if present. The file defines additional fonts available to the + application, and has the following format: + + \snippet doc/src/snippets/code/doc_src_emb-fonts.qdoc 0 + + \table 100% + \header \o Field \o Description + \row \o \bold name + \o The name of the font format, e.g.,\c Helvetica, \c Times, etc. + \row \o \bold file + \o The name of the file containing the font, e.g., \c + helvR0810.bdf, \c verdana.ttf, etc. + \row \o \bold renderer + \o Specifies the font engine that should be used to render the + font, currently only the FreeType font engine (\c FT) is + supported. + \row \o \bold italic + \o Specifies whether the font is italic or not; the accepted + values are \c y or \c n. + \row \o \bold weight + \o Specifies the font's weight: \c 50 is normal, \c 75 is bold, + etc. + \row \o \bold size + \o Specifies the font size, i.e., point size * 10. For example, a + value of 120 means 12pt. A value of 0 means that the font is + scalable. + \row \o \bold flags + \o The following flag is supported: + \list + \o \c s: smooth (anti-aliased) + \endlist + All other flags are ignored. + \endtable +*/ |