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authorLars Knoll <lars.knoll@nokia.com>2009-03-23 09:18:55 (GMT)
committerSimon Hausmann <simon.hausmann@nokia.com>2009-03-23 09:18:55 (GMT)
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Long live Qt 4.5!
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+/****************************************************************************
+**
+** 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
+*/