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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** 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, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, 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.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
/*
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 <QtXml>
#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);
fetchButton = new QPushButton(tr("Fetch"), this);
abortButton = new QPushButton(tr("Abort"), this);
abortButton->setEnabled(false);
treeWidget = new QTreeWidget(this);
QStringList headerLabels;
headerLabels << tr("Title") << tr("Link");
treeWidget->setHeaderLabels(headerLabels);
handler = 0;
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"));
}
/*
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.
We reset the flag used to determine whether parsing should begin again
or continue. A new handler is created, if required, and made available
to the reader.
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();
lastItemCreated = 0;
newInformation = true;
if (handler != 0)
delete handler;
handler = new Handler;
//! [0]
xmlReader.setContentHandler(handler);
xmlReader.setErrorHandler(handler);
//! [0]
connect(handler, SIGNAL(newItem(QString &, QString &)),
this, SLOT(addItem(QString &, QString &)));
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
input source. The first time we receive new information,
the reader is set up for a new incremental parse;
we continue parsing using a different function on
subsequent calls involving the same data source.
If parsing fails for any reason, we abort the fetch.
*/
//! [1]
void RSSListing::readData(const QHttpResponseHeader &resp)
{
bool ok;
if (resp.statusCode() != 200)
http.abort();
else {
xmlInput.setData(http.readAll());
if (newInformation) {
ok = xmlReader.parse(&xmlInput, true);
newInformation = false;
}
else
ok = xmlReader.parseContinue();
if (!ok)
http.abort();
}
}
//! [1]
/*
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 perform a final
parsing operation on the data returned to ensure that it was
well-formed. Whether this is successful or not, 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) {
bool ok = xmlReader.parseContinue();
if (!ok)
qWarning("Parse error at the end of input.");
lineEdit->setReadOnly(false);
abortButton->setEnabled(false);
fetchButton->setEnabled(true);
}
}
/*
Adds an item to the list view as it is reported by the handler.
We keep a record of the last item created to ensure that the
items are created in sequence.
*/
void RSSListing::addItem(QString &title, QString &link)
{
QTreeWidgetItem *item;
item = new QTreeWidgetItem(treeWidget, lastItemCreated);
item->setText(0, title);
item->setText(1, link);
lastItemCreated = item;
}
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