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<title>Qt 4.6: rsslisting.cpp Example File (xml/rsslisting/rsslisting.cpp)</title>
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<pre><span class="comment"> /****************************************************************************
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<span class="comment"> /*
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.
*/</span>
#include <QtCore>
#include <QtGui>
#include <QtNetwork>
#include "rsslisting.h"
<span class="comment"> /*
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.
*/</span>
RSSListing::RSSListing(QWidget *parent)
: QWidget(parent)
{
lineEdit = new QLineEdit(this);
lineEdit->setText("http:<span class="comment">//labs.qt.nokia.com/blogs/feed");</span>
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(QHttpResponseHeader)),
this, SLOT(readData(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);
}
<span class="comment"> /*
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.
*/</span>
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());
}
<span class="comment"> /*
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.
*/</span>
void RSSListing::readData(const QHttpResponseHeader &resp)
{
if (resp.statusCode() != 200)
http.abort();
else {
xml.addData(http.readAll());
parseXml();
}
}
<span class="comment"> /*
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.
*/</span>
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);
}
}
<span class="comment"> /*
Parses the XML data and creates treeWidget items accordingly.
*/</span>
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();
}
}
<span class="comment"> /*
Open the link in the browser
*/</span>
void RSSListing::itemActivated(QTreeWidgetItem * item)
{
QDesktopServices::openUrl(QUrl(item->text(1)));
}</pre>
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distrib
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Mandriva
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current
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i586
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media
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main-updates
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8e6051afcdb111a0317a58fb64c2abf5
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files
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