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
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
|
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Qt Software Information (qt-info@nokia.com)
**
** This file is part of the examples 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.
** $QT_END_LICENSE$
**
****************************************************************************/
/*
rsslisting.cpp
Provides a widget for displaying news items from RDF news sources.
RDF is an XML-based format for storing items of information (see
http://www.w3.org/RDF/ for details).
The widget itself provides a simple user interface for specifying
the URL of a news source, and controlling the downloading of news.
The widget downloads and parses the XML asynchronously, feeding the
data to an XML reader in pieces. This allows the user to interrupt
its operation, and also allows very large data sources to be read.
*/
#include <QtCore>
#include <QtGui>
#include <QtNetwork>
#include "rsslisting.h"
/*
Constructs an RSSListing widget with a simple user interface, and sets
up the XML reader to use a custom handler class.
The user interface consists of a line edit, two push buttons, and a
list view widget. The line edit is used for entering the URLs of news
sources; the push buttons start and abort the process of reading the
news.
*/
RSSListing::RSSListing(QWidget *parent)
: QWidget(parent)
{
lineEdit = new QLineEdit(this);
lineEdit->setText("http://labs.trolltech.com/blogs/feed");
fetchButton = new QPushButton(tr("Fetch"), this);
abortButton = new QPushButton(tr("Abort"), this);
abortButton->setEnabled(false);
treeWidget = new QTreeWidget(this);
connect(treeWidget, SIGNAL(itemActivated(QTreeWidgetItem*, int)),
this, SLOT(itemActivated(QTreeWidgetItem*)));
QStringList headerLabels;
headerLabels << tr("Title") << tr("Link");
treeWidget->setHeaderLabels(headerLabels);
treeWidget->header()->setResizeMode(QHeaderView::ResizeToContents);
connect(&http, SIGNAL(readyRead(const QHttpResponseHeader &)),
this, SLOT(readData(const QHttpResponseHeader &)));
connect(&http, SIGNAL(requestFinished(int, bool)),
this, SLOT(finished(int, bool)));
connect(lineEdit, SIGNAL(returnPressed()), this, SLOT(fetch()));
connect(fetchButton, SIGNAL(clicked()), this, SLOT(fetch()));
connect(abortButton, SIGNAL(clicked()), &http, SLOT(abort()));
QVBoxLayout *layout = new QVBoxLayout(this);
QHBoxLayout *hboxLayout = new QHBoxLayout;
hboxLayout->addWidget(lineEdit);
hboxLayout->addWidget(fetchButton);
hboxLayout->addWidget(abortButton);
layout->addLayout(hboxLayout);
layout->addWidget(treeWidget);
setWindowTitle(tr("RSS listing example"));
resize(640,480);
}
/*
Starts fetching data from a news source specified in the line
edit widget.
The line edit is made read only to prevent the user from modifying its
contents during the fetch; this is only for cosmetic purposes.
The fetch button is disabled, and the abort button is enabled to allow
the user to interrupt processing. The list view is cleared, and we
define the last list view item to be 0, meaning that there are no
existing items in the list.
The HTTP handler is supplied with the raw contents of the line edit and
a fetch is initiated. We keep the ID value returned by the HTTP handler
for future reference.
*/
void RSSListing::fetch()
{
lineEdit->setReadOnly(true);
fetchButton->setEnabled(false);
abortButton->setEnabled(true);
treeWidget->clear();
xml.clear();
QUrl url(lineEdit->text());
http.setHost(url.host());
connectionId = http.get(url.path());
}
/*
Reads data received from the RDF source.
We read all the available data, and pass it to the XML
stream reader. Then we call the XML parsing function.
If parsing fails for any reason, we abort the fetch.
*/
void RSSListing::readData(const QHttpResponseHeader &resp)
{
if (resp.statusCode() != 200)
http.abort();
else {
xml.addData(http.readAll());
parseXml();
}
}
/*
Finishes processing an HTTP request.
The default behavior is to keep the text edit read only.
If an error has occurred, the user interface is made available
to the user for further input, allowing a new fetch to be
started.
If the HTTP get request has finished, we make the
user interface available to the user for further input.
*/
void RSSListing::finished(int id, bool error)
{
if (error) {
qWarning("Received error during HTTP fetch.");
lineEdit->setReadOnly(false);
abortButton->setEnabled(false);
fetchButton->setEnabled(true);
}
else if (id == connectionId) {
lineEdit->setReadOnly(false);
abortButton->setEnabled(false);
fetchButton->setEnabled(true);
}
}
/*
Parses the XML data and creates treeWidget items accordingly.
*/
void RSSListing::parseXml()
{
while (!xml.atEnd()) {
xml.readNext();
if (xml.isStartElement()) {
if (xml.name() == "item")
linkString = xml.attributes().value("rss:about").toString();
currentTag = xml.name().toString();
} else if (xml.isEndElement()) {
if (xml.name() == "item") {
QTreeWidgetItem *item = new QTreeWidgetItem;
item->setText(0, titleString);
item->setText(1, linkString);
treeWidget->addTopLevelItem(item);
titleString.clear();
linkString.clear();
}
} else if (xml.isCharacters() && !xml.isWhitespace()) {
if (currentTag == "title")
titleString += xml.text().toString();
else if (currentTag == "link")
linkString += xml.text().toString();
}
}
if (xml.error() && xml.error() != QXmlStreamReader::PrematureEndOfDocumentError) {
qWarning() << "XML ERROR:" << xml.lineNumber() << ": " << xml.errorString();
http.abort();
}
}
/*
Open the link in the browser
*/
void RSSListing::itemActivated(QTreeWidgetItem * item)
{
QDesktopServices::openUrl(QUrl(item->text(1)));
}
|
