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/****************************************************************************
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**
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** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
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** All rights reserved.
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** Contact: Nokia Corporation (qt-info@nokia.com)
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**
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** This file is part of the documentation of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** No Commercial Usage
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** This file contains pre-release code and may not be distributed.
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** You may use this file in accordance with the terms and conditions
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** contained in the Technology Preview License Agreement accompanying
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** this package.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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/*!
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\page qt-embedded-fonts.html
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\title Qt for Embedded Linux Fonts
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\ingroup qt-embedded-linux
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\l {Qt for Embedded Linux} uses the
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\l{http://freetype.sourceforge.net/freetype2/index.html}{FreeType 2}
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font engine to produce font output. The formats supported depends on
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the locally installed version of the FreeType library. In addition,
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\l{Qt for Embedded Linux} supports the Qt Prerendered Font formats (\l QPF and \l QPF2):
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light-weight non-scalable font formats specific to \l {Qt for Embedded Linux}.
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QPF2 is the native format of \l{Qt for Embedded Linux}. QPF is the legacy
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format used by Qt/Embedded 2.x and 3.x. Several of the formats may be rendered
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using anti-aliasing for improved readability.
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When \l{Qt for Embedded Linux} applications run, they look for fonts in
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Qt's \c lib/fonts/ directory. \l {Qt for Embedded Linux} will automatically detect
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prerendered fonts and TrueType fonts. For compatibility, it will also read the
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legacy \c lib/fonts/fontdir file.
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Support for other font formats can be added, contact
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\l{mailto:qt-info@nokia.com}{qt-info@nokia.com} for more
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information.
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\tableofcontents
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\table 100%
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\row
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\o
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\bold {Optimization}
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The \l FreeType, \l QPF2 and \l QPF formats are features that can be
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disabled using the
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\l{Fine-Tuning Features in Qt}{feature definition system},
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reducing the size of Qt and saving resources.
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Note that at least one font format must be defined.
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See the \l {Fine-Tuning Features in Qt} documentation for
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details.
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\o
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\inlineimage qt-embedded-fontfeatures.png
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\endtable
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All supported fonts use the Unicode character encoding. Most fonts
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available today do, but they usually don't contain \e all the
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Unicode characters. A complete 16-point Unicode font uses over 1
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MB of memory.
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\target FreeType
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\section1 FreeType Formats
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The \l {http://freetype.sourceforge.net/freetype2/index.html}{FreeType 2}
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library (and therefore \l{Qt for Embedded Linux}) can support the following font formats:
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\list
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\o TrueType (TTF)
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\o PostScript Type1 (PFA/PFB)
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\o Bitmap Distribution Format (BDF)
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\o CID-keyed Type1
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\o Compact Font Format (CFF)
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\o OpenType fonts
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\o SFNT-based bitmap fonts
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\o Portable Compiled Format (PCF)
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\o Microsoft Windows Font File Format (Windows FNT)
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\o Portable Font Resource (PFR)
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\o Type 42 (limited support)
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\endlist
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It is possible to add modules to the \l
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{http://freetype.sourceforge.net/freetype2/index.html}{FreeType 2}
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font engine to support other types of font files. For more
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information, see the font engine's own website: \l
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http://freetype.sourceforge.net/freetype2/index.html.
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Glyphs rendered using FreeType are shared efficiently between applications,
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reducing memory requirements and speeding up text rendering.
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\omit
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\l {Qt for Embedded Linux} will by default use the system FreeType library if it exists.
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Otherwise it will use a copy of the FreeType library in Qt, which by default only
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supports TrueType fonts to reduce footprint.
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\endomit
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\target QPF2
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\section1 Qt Prerendered Font (QPF2)
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The Qt Prerendered Font (QPF2) is an architecture-independent,
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light-weight and non-scalable font format specific to \l{Qt for Embedded Linux}.
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Nokia provides the cross-platform \l makeqpf tool, included in the
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\c tools directory of both \l {Qt} and \l{Qt for Embedded Linux}, which allows
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generation of QPF2 files from system fonts.
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QPF2 supports anti-aliasing and complex writing systems, using information
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from the corresponding TrueType font, if present on the system. The format
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is designed to be mapped directly to memory. The same format is used to
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share glyphs from non-prerendered fonts between applications.
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\target QPF
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\section1 Legacy Qt Prerendered Font (QPF)
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Nokia provides support for the legacy QPF format for compatibility
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reasons. QPF is based on the internal font engine data structure of Qt/Embedded
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versions 2 and 3.
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Note that the file name describes the font, for example \c helvetica_120_50.qpf
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is 12 point Helvetica while \c helvetica_120_50i.qpf is 12 point Helvetica \e italic.
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\omit
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\section1 Memory Requirements
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Taking advantage of the way the QPF format is structured, Qt for
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Embedded Linux memory-maps the data rather than reading and parsing it.
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This reduces RAM consumption even further.
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Scalable fonts use a larger amount of memory per font, but
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these fonts provide a memory saving if many different sizes of each
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font are needed.
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\endomit
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\section1 The Legacy \c fontdir File
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For compatibility reasons \l{Qt for Embedded Linux} supports the \c fontdir
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file, if present. The file defines additional fonts available to the
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application, and has the following format:
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\snippet doc/src/snippets/code/doc_src_emb-fonts.qdoc 0
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\table 100%
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\header \o Field \o Description
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\row \o \bold name
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\o The name of the font format, e.g.,\c Helvetica, \c Times, etc.
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\row \o \bold file
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\o The name of the file containing the font, e.g., \c
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helvR0810.bdf, \c verdana.ttf, etc.
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\row \o \bold renderer
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\o Specifies the font engine that should be used to render the
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font, currently only the FreeType font engine (\c FT) is
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supported.
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\row \o \bold italic
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\o Specifies whether the font is italic or not; the accepted
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values are \c y or \c n.
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\row \o \bold weight
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\o Specifies the font's weight: \c 50 is normal, \c 75 is bold,
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etc.
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\row \o \bold size
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\o Specifies the font size, i.e., point size * 10. For example, a
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value of 120 means 12pt. A value of 0 means that the font is
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scalable.
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\row \o \bold flags
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\o The following flag is supported:
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\list
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\o \c s: smooth (anti-aliased)
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\endlist
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All other flags are ignored.
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\endtable
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*/
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