File: richtext-common-tasks.html

package info (click to toggle)
qt4-x11 4%3A4.8.2%2Bdfsg-11
  • links: PTS, VCS
  • area: main
  • in suites: wheezy
  • size: 701,696 kB
  • sloc: cpp: 2,686,179; ansic: 375,485; python: 25,859; sh: 19,349; xml: 17,091; perl: 14,765; yacc: 5,383; asm: 5,038; makefile: 1,259; lex: 555; ruby: 526; objc: 347; cs: 112; pascal: 112; php: 54; sed: 34
file content (122 lines) | stat: -rw-r--r-- 10,624 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en_US" lang="en_US">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<!-- richtext.qdoc -->
  <title>Qt 4.8: Common Rich Text Editing Tasks</title>
  <link rel="stylesheet" type="text/css" href="style/offline.css" />
</head>
<body>
<div class="header" id="qtdocheader">
  <div class="content"> 
    <a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
  </div>
  <div class="breadcrumb toolblock">
    <ul>
      <li class="first"><a href="index.html">Home</a></li>
      <!--  Breadcrumbs go here -->
<li>Common Rich Text Editing Tasks</li>
    </ul>
  </div>
</div>
<div class="content mainContent">
  <link rel="prev" href="richtext-layouts.html" />
  <link rel="next" href="richtext-advanced-processing.html" />
<p class="naviNextPrevious headerNavi">
<a class="prevPage" href="richtext-layouts.html">Document Layouts</a>
<a class="nextPage" href="richtext-advanced-processing.html">Advanced Rich Text Processing</a>
</p><p/>
<div class="toc">
<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#using-qtextedit">Using QTextEdit</a></li>
<li class="level1"><a href="#selecting-text">Selecting Text</a></li>
<li class="level1"><a href="#finding-text">Finding Text</a></li>
<li class="level1"><a href="#printing-documents">Printing Documents</a></li>
</ul>
</div>
<h1 class="title">Common Rich Text Editing Tasks</h1>
<span class="subtitle"></span>
<!-- $$$richtext-common-tasks.html-description -->
<div class="descr"> <a name="details"></a>
<p>There are a number of tasks that are often performed by developers when editing and processing text documents using Qt. These include the use of display widgets such as <a href="qtextbrowser.html">QTextBrowser</a> and <a href="qtextedit.html">QTextEdit</a>, creation of documents with <a href="qtextdocument.html">QTextDocument</a>, editing using a <a href="qtextcursor.html">QTextCursor</a>, and exporting the document structure. This document outlines some of the more common ways of using the rich text classes to perform these tasks, showing convenient patterns that can be reused in your own applications.</p>
<a name="using-qtextedit"></a>
<h2>Using QTextEdit</h2>
<p>A text editor widget can be constructed and used to display HTML in the following way:</p>
<pre class="cpp"> <span class="type"><a href="qtextedit.html">QTextEdit</a></span> <span class="operator">*</span>editor <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qtextedit.html">QTextEdit</a></span>(parent);
 editor<span class="operator">-</span><span class="operator">&gt;</span>setHtml(aStringContainingHTMLtext);
 editor<span class="operator">-</span><span class="operator">&gt;</span>show();</pre>
<p>By default, the text editor contains a document with a root frame, inside which is an empty text block. This document can be obtained so that it can be modified directly by the application:</p>
<pre class="cpp"> <span class="type"><a href="qtextdocument.html">QTextDocument</a></span> <span class="operator">*</span>document <span class="operator">=</span> editor<span class="operator">-</span><span class="operator">&gt;</span>document();</pre>
<p>The text editor's cursor may also be used to edit a document:</p>
<pre class="cpp"> <span class="type"><a href="qtextcursor.html">QTextCursor</a></span> cursor <span class="operator">=</span> editor<span class="operator">-</span><span class="operator">&gt;</span>textCursor();</pre>
<p>Although a document can be edited using many cursors at once, a <a href="qtextedit.html">QTextEdit</a> only displays a single cursor at a time. Therefore, if we want to update the editor to display a particular cursor or its selection, we need to set the editor's cursor after we have modified the document:</p>
<pre class="cpp"> editor<span class="operator">-</span><span class="operator">&gt;</span>setTextCursor(cursor);</pre>
<a name="selecting-text"></a>
<h2>Selecting Text</h2>
<p>Text is selected by moving the cursor using operations that are similar to those performed by a user in a text editor. To select text between two points in the document, we need to position the cursor at the first point then move it using a special mode (<a href="qtextcursor.html#MoveMode-enum">QTextCursor::MoveMode</a>) with a move operation (<a href="qtextcursor.html#MoveOperation-enum">QTextCursor::MoveOperation</a>). When we select the text, we leave the selection anchor at the old cursor position just as the user might do by holding down the Shift key when selecting text:</p>
<pre class="cpp">     cursor<span class="operator">.</span>movePosition(<span class="type"><a href="qtextcursor.html">QTextCursor</a></span><span class="operator">::</span>StartOfWord);
     cursor<span class="operator">.</span>movePosition(<span class="type"><a href="qtextcursor.html">QTextCursor</a></span><span class="operator">::</span>EndOfWord<span class="operator">,</span> <span class="type"><a href="qtextcursor.html">QTextCursor</a></span><span class="operator">::</span>KeepAnchor);</pre>
<p>In the above code, a whole word is selected using this method. <a href="qtextcursor.html">QTextCursor</a> provides a number of common move operations for selecting individual characters, words, lines, and whole blocks.</p>
<a name="finding-text"></a>
<h2>Finding Text</h2>
<p><a href="qtextdocument.html">QTextDocument</a> provides a cursor-based interface for searching, making it easy to find and modify text in the style of a text editor. The following code finds all the instances of a particular word in a document, and changes the color of each:</p>
<pre class="cpp">     <span class="type"><a href="qtextcursor.html">QTextCursor</a></span> newCursor(document);

     <span class="keyword">while</span> (<span class="operator">!</span>newCursor<span class="operator">.</span>isNull() <span class="operator">&amp;</span><span class="operator">&amp;</span> <span class="operator">!</span>newCursor<span class="operator">.</span>atEnd()) {
         newCursor <span class="operator">=</span> document<span class="operator">-</span><span class="operator">&gt;</span>find(searchString<span class="operator">,</span> newCursor);

         <span class="keyword">if</span> (<span class="operator">!</span>newCursor<span class="operator">.</span>isNull()) {
             newCursor<span class="operator">.</span>movePosition(<span class="type"><a href="qtextcursor.html">QTextCursor</a></span><span class="operator">::</span>WordRight<span class="operator">,</span>
                                    <span class="type"><a href="qtextcursor.html">QTextCursor</a></span><span class="operator">::</span>KeepAnchor);

             newCursor<span class="operator">.</span>mergeCharFormat(colorFormat);
         }
     }</pre>
<p>Note that the cursor does not have to be moved after each search and replace operation; it is always positioned at the end of the word that was just replaced.</p>
<a name="printing-documents"></a>
<h2>Printing Documents</h2>
<p><a href="qtextedit.html">QTextEdit</a> is designed for the display of large rich text documents that are read on screen, rendering them in the same way as a web browser. As a result, it does not automatically break the contents of the document into page-sized pieces that are suitable for printing.</p>
<p><a href="qtextdocument.html">QTextDocument</a> provides a <a href="qtextdocument.html#print">print()</a> function to allow documents to be printed using the <a href="qprinter.html">QPrinter</a> class. The following code shows how to prepare a document in a <a href="qtextedit.html">QTextEdit</a> for printing with a <a href="qprinter.html">QPrinter</a>:</p>
<pre class="cpp">     <span class="type"><a href="qtextdocument.html">QTextDocument</a></span> <span class="operator">*</span>document <span class="operator">=</span> editor<span class="operator">-</span><span class="operator">&gt;</span>document();
     <span class="type"><a href="qprinter.html">QPrinter</a></span> printer;

     <span class="type"><a href="qprintdialog.html">QPrintDialog</a></span> <span class="operator">*</span>dlg <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qprintdialog.html">QPrintDialog</a></span>(<span class="operator">&amp;</span>printer<span class="operator">,</span> <span class="keyword">this</span>);
     <span class="keyword">if</span> (dlg<span class="operator">-</span><span class="operator">&gt;</span>exec() <span class="operator">!</span><span class="operator">=</span> <span class="type"><a href="qdialog.html">QDialog</a></span><span class="operator">::</span>Accepted)
         <span class="keyword">return</span>;

     document<span class="operator">-</span><span class="operator">&gt;</span>print(<span class="operator">&amp;</span>printer);</pre>
<p>The document is obtained from the text editor, and a <a href="qprinter.html">QPrinter</a> is constructed then configured using a <a href="qprintdialog.html">QPrintDialog</a>. If the user accepts the printer's configuration then the document is formatted and printed using the <a href="qtextdocument.html#print">print()</a> function.</p>
</div>
<!-- @@@richtext-common-tasks.html -->
<p class="naviNextPrevious footerNavi">
<a class="prevPage" href="richtext-layouts.html">Document Layouts</a>
<a class="nextPage" href="richtext-advanced-processing.html">Advanced Rich Text Processing</a>
</p>
  <div class="ft">
    <span></span>
  </div>
</div> 
<div class="footer">
    <p>
      <acronym title="Copyright">&copy;</acronym> 2012 Nokia Corporation and/or its
      subsidiaries. Documentation contributions included herein are the copyrights of
      their respective owners.</p>
    <br />
    <p>
      The documentation provided herein is licensed under the terms of the
      <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation
      License version 1.3</a> as published by the Free Software Foundation.</p>
    <p>
      Documentation sources may be obtained from <a href="http://www.qt-project.org">
      www.qt-project.org</a>.</p>
    <br />
    <p>
      Nokia, Qt and their respective logos are trademarks of Nokia Corporation 
      in Finland and/or other countries worldwide. All other trademarks are property
      of their respective owners. <a title="Privacy Policy"
      href="http://en.gitorious.org/privacy_policy/">Privacy Policy</a></p>
</div>
</body>
</html>