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Diffstat (limited to 'doc/codesnippets/doc/src/snippets/xml/rsslisting/rsslisting.cpp')
| -rw-r--r-- | doc/codesnippets/doc/src/snippets/xml/rsslisting/rsslisting.cpp | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/doc/codesnippets/doc/src/snippets/xml/rsslisting/rsslisting.cpp b/doc/codesnippets/doc/src/snippets/xml/rsslisting/rsslisting.cpp new file mode 100644 index 000000000..2740bd2c9 --- /dev/null +++ b/doc/codesnippets/doc/src/snippets/xml/rsslisting/rsslisting.cpp @@ -0,0 +1,246 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial Usage +** Licensees holding valid Qt Commercial licenses may use this file in +** accordance with the Qt Commercial License Agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and Nokia. +** +** 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 http://www.qtsoftware.com/contact. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/* +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] +def readData(self, resp): + if resp.statusCode() != 200: + self.http.abort() + else: + xmlInput.setData(self.http.readAll()) + + if newInformation: + ok = xmlReader.parse(xmlInput, True) + newInformation = False + else: + ok = xmlReader.parseContinue() + + if not ok: + self.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; +} + |