| 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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| 4 | ** All rights reserved.
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| 5 | ** Contact: Nokia Corporation ([email protected])
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| 6 | **
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| 7 | ** This file is part of the documentation of the Qt Toolkit.
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| 8 | **
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| 9 | ** $QT_BEGIN_LICENSE:FDL$
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| 10 | ** Commercial Usage
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| 11 | ** Licensees holding valid Qt Commercial licenses may use this file in
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| 12 | ** accordance with the Qt Commercial License Agreement provided with the
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| 13 | ** Software or, alternatively, in accordance with the terms contained in a
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| 14 | ** written agreement between you and Nokia.
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| 15 | **
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| 16 | ** GNU Free Documentation License
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| 17 | ** Alternatively, this file may be used under the terms of the GNU Free
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| 18 | ** Documentation License version 1.3 as published by the Free Software
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| 20 | ** file.
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| 22 | ** If you have questions regarding the use of this file, please contact
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| 23 | ** Nokia at [email protected].
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| 24 | ** $QT_END_LICENSE$
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| 26 | ****************************************************************************/
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| 27 |
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| 28 | /*!
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| 29 | \page qt4-scribe.html
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| 30 | \title The Scribe Classes
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| 31 |
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| 32 | \contentspage {What's New in Qt 4}{Home}
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| 33 | \previouspage The Arthur Paint System
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| 34 | \nextpage The Qt 4 Main Window Classes
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| 35 |
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| 36 | \keyword Scribe
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| 37 |
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| 38 | Scribe introduces a set of text layout classes to Qt 4. These classes
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| 39 | replace the old rich text engine found in Qt 3, and provide new features
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| 40 | for processing and laying out both plain and rich text.
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| 41 |
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| 42 | \tableofcontents
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| 43 |
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| 44 | For more details about how to use the Scribe classes, see the
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| 45 | \l{richtext.html}{Rich Text Processing} document.
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| 46 |
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| 47 | \section1 Overview of Scribe
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| 48 |
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| 49 | Support for text rendering and layout in Qt 4 has been redesigned
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| 50 | around a system that allows textual content to be represented in a more
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| 51 | flexible way than was possible with Qt 3. Qt 4 also provides a more
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| 52 | convenient programming interface for editing documents. These
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| 53 | improvements are made available through a reimplementation of the
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| 54 | existing text rendering engine, and the introduction of several new
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| 55 | classes.
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| 56 |
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| 57 | The following sections provide a brief overview of the main concepts
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| 58 | behind Scribe.
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| 59 |
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| 60 | \section2 The Document Interface
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| 61 |
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| 62 | Text documents are represented by the QTextDocument class, rather
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| 63 | than by QString objects. Each QTextDocument object contains
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| 64 | information about the document's internal representation, its
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| 65 | structure, and keeps track of modifications to provide undo/redo
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| 66 | facilities.
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| 67 | This approach allows features such as layout management to be
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| 68 | delegated to specialized classes, but also provides a focus for the
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| 69 | framework.
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| 70 |
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| 71 | Documents are either converted from external sources or created from
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| 72 | scratch using Qt. The creation process can done by an editor widget,
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| 73 | such as QTextEdit, or by explicit calls to the Scribe API.
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| 74 |
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| 75 | Text documents can be accessed in two complementary ways: as a linear
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| 76 | buffer for editors to use, and as an object hierarchy that is useful to
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| 77 | layout engines.
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| 78 | In the hierarchical document model, objects generally correspond to
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| 79 | visual elements such as frames, tables, and lists. At a lower level,
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| 80 | these elements describe properties such as the text style and alignment.
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| 81 | The linear representation of the document is used for editing and
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| 82 | manipulation of the document's contents.
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| 83 |
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| 84 | \section2 Document Structure
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| 85 |
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| 86 | Each document contains a root frame into which all other structural
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| 87 | elements are placed. This frame contains other structural elements,
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| 88 | including tables, text blocks, and other frames; these can be nested to
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| 89 | an arbitrary depth.
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| 90 |
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| 91 | Frames provide logical separation between parts of the document, but
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| 92 | also have properties that determine how they will appear when rendered.
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| 93 | A table is a specialized type of frame that consists of a number of
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| 94 | cells, arranged into rows and columns, each of which can contain
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