diff options
Diffstat (limited to 'src/xml/doc/snippets/rsslisting')
| -rw-r--r-- | src/xml/doc/snippets/rsslisting/handler.cpp | 182 | ||||
| -rw-r--r-- | src/xml/doc/snippets/rsslisting/rsslisting.cpp | 251 |
2 files changed, 433 insertions, 0 deletions
diff --git a/src/xml/doc/snippets/rsslisting/handler.cpp b/src/xml/doc/snippets/rsslisting/handler.cpp new file mode 100644 index 0000000000..5cd2c45023 --- /dev/null +++ b/src/xml/doc/snippets/rsslisting/handler.cpp @@ -0,0 +1,182 @@ +/**************************************************************************** +** +** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). +** Contact: http://www.qt-project.org/ +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** You may use this file under the terms of the BSD license as follows: +** +** "Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions are +** met: +** * Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** * Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor +** the names of its contributors may be used to endorse or promote +** products derived from this software without specific prior written +** permission. +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/* +handler.cpp + +Provides a handler for processing XML elements found by the reader. + +The handler looks for <title> and <link> elements within <item> elements, +and records the text found within them. Link information stored within +rdf:about attributes of <item> elements is also recorded when it is +available. + +For each item found, a signal is emitted which specifies its title and +link information. This may be used by user interfaces for the purpose of +displaying items as they are read. +*/ + +#include <QtGui> + +#include "handler.h" + +/* + Reset the state of the handler to ensure that new documents are + read correctly. + + We return true to indicate that parsing should continue. +*/ + +bool Handler::startDocument() +{ + inItem = false; + inTitle = false; + inLink = false; + + return true; +} + +/* + Process each starting element in the XML document. + + Nested item, title, or link elements are not allowed, so we return false + if we encounter any of these. We also prohibit multiple definitions of + title strings. + + Link destinations are read by this function if they are specified as + attributes in item elements. + + For all cases not explicitly checked for, we return true to indicate that + the element is acceptable, and that parsing should continue. By doing + this, we can ignore elements in which we are not interested. +*/ + +bool Handler::startElement(const QString &, const QString &, + const QString & qName, const QXmlAttributes &attr) +{ + if (qName == "item") { + + if (inItem) + return false; + else { + inItem = true; + linkString = attr.value("rdf:about"); + } + } + else if (qName == "title") { + + if (inTitle) + return false; + else if (!titleString.isEmpty()) + return false; + else if (inItem) + inTitle = true; + } + else if (qName == "link") { + + if (inLink) + return false; + else if (inItem) + inLink = true; + } + + return true; +} + +/* + Process each ending element in the XML document. + + For recognized elements, we reset flags to ensure that we can read new + instances of these elements. If we have read an item element, emit a + signal to indicate that a new item is available for display. + + We return true to indicate that parsing should continue. +*/ + +bool Handler::endElement(const QString &, const QString &, + const QString & qName) +{ + if (qName == "title" && inTitle) + inTitle = false; + else if (qName == "link" && inLink) + inLink = false; + else if (qName == "item") { + if (!titleString.isEmpty() && !linkString.isEmpty()) + emit newItem(titleString, linkString); + inItem = false; + titleString = ""; + linkString = ""; + } + + return true; +} + +/* + Collect characters when reading the contents of title or link elements + when they occur within an item element. + + We return true to indicate that parsing should continue. +*/ + +bool Handler::characters (const QString &chars) +{ + if (inTitle) + titleString += chars; + else if (inLink) + linkString += chars; + + return true; +} + +/* + Report a fatal parsing error, and return false to indicate to the reader + that parsing should stop. +*/ + +//! [0] +bool Handler::fatalError (const QXmlParseException & exception) +{ + qWarning() << "Fatal error on line" << exception.lineNumber() + << ", column" << exception.columnNumber() << ":" + << exception.message(); + + return false; +} +//! [0] diff --git a/src/xml/doc/snippets/rsslisting/rsslisting.cpp b/src/xml/doc/snippets/rsslisting/rsslisting.cpp new file mode 100644 index 0000000000..5fb7c28da9 --- /dev/null +++ b/src/xml/doc/snippets/rsslisting/rsslisting.cpp @@ -0,0 +1,251 @@ +/**************************************************************************** +** +** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies). +** Contact: http://www.qt-project.org/ +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:BSD$ +** You may use this file under the terms of the BSD license as follows: +** +** "Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions are +** met: +** * Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** * Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor +** the names of its contributors may be used to endorse or promote +** products derived from this software without specific prior written +** permission. +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/* +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; +} + |