doc/src/platforms/emb-fonts.qdoc
changeset 7 f7bc934e204c
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+++ b/doc/src/platforms/emb-fonts.qdoc	Wed Mar 31 11:06:36 2010 +0300
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+/****************************************************************************
+**
+** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (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 Technology Preview License Agreement accompanying
+** this package.
+**
+** 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
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+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@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. To make a suggestion,
+    please create a task in our bug tracker at \l
+    {http://bugreports.qt.nokia.com}{http://bugreports.qt.nokia.com}.
+
+    \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 \l 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
+*/