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diff --git a/examples/corelib/serialization/rsslisting/doc/src/rsslisting.qdoc b/examples/corelib/serialization/rsslisting/doc/src/rsslisting.qdoc deleted file mode 100644 index b86fab1e1b..0000000000 --- a/examples/corelib/serialization/rsslisting/doc/src/rsslisting.qdoc +++ /dev/null @@ -1,129 +0,0 @@ -// Copyright (C) 2023 The Qt Company Ltd. -// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only - -/*! - \example serialization/rsslisting - \examplecategory {Networking} - \meta tag {serialization} - \title A minimal RSS listing application - - \brief A demonstration of how to fetch and display a network resource. - - This example shows how to fetch a resource the user has requested and - display data contained in the response, illustrated by an RSS listing - application. (RDF Site Summary, or Really Simple Syndication, is a standard - format for communicating updates to web sites. See - https://www.rssboard.org/rss-specification for details.) The user inferface - in the illustration is simple, as the focus of this example is on how to use - networking, but naturally a more sophisticated interface would be wanted for - a serious RSS reader. - - The example also illustrates how to do asynchronous parsing of data as it is - received, preserving state in member variables so that an incremental parser - can consume chunks of data as they arrive over the network. Constituents of - the parsed content may start in one chunk of data but not be completed until - a later chunk, requiring the parser to retain state between calls. - - \image rsslisting.cpp - - The main program is fairly minimal. It simply instantiates a \l QApplication - and the \c RSSListing widget, shows the latter and hands over control to the - former. For the sake of illustration, it gives the widget the Qt blog's URL - as default value for the resource to check. - - \snippet serialization/rsslisting/main.cpp 0 - - \section1 The RSSListing class - - \snippet serialization/rsslisting/rsslisting.h 0 - - The widget itself provides a simple user interface for specifying the URL to - fetch and, once available updates are displayed, controlling the downloading - of updated items. A \l QLineEdit provides for input of the URL, and a - \l QTreeWidget for display of the results once fetched. - - The widget downloads and parses the RSS (a form of XML) asynchronously, - feeding the data to an XML reader as it arrives. This supports reading of - very large data sources. Because the data is streamed from the network - through the XML reader, there is no need to retain the full text of the XML - in memory. In other context, a similar approach can allow the user to - interrupt such incremental loading. - - \section2 Construction - - \snippet serialization/rsslisting/rsslisting.cpp setup - - The constructor sets up the assorted components of the widget and connects - their various signals to the slots it shall use to handle them. - - The user interface consists of a line edit, a push button, and a list view - widget. The line edit is used for entering the URL to fetch; the push button - starts the process of fetching updates. The line edit is empty by default, - but the constructor's caller can override that, as our \c main() has done. - In any case, the user can replace the default with the URL of another RSS - feed. - - The list view shows the updated items reported in the RSS feed. - Double-clicking on one of these sends its URL to the user's browser or other - user agent using \l QDesktopServices::openUrl(). - - \section2 The slots - - \snippet serialization/rsslisting/rsslisting.cpp slots - - All slots are kept simple by delegating any hard work to private methods. - - When the user completes input of a URL, either by clicking the "Fetch" - button or by pressing the return key in the line edit, the \c fetch() slot - disables the "Fetch" button and disables further editing of the line edit. - It clears the display of available updates and delegates to \c get() the - initiating of an HTTP GET request. - - When data is received, the network reply triggers its \l {QNetworkReply::} - {readyRead()} signal, which \c get() connects to the \c consumeData() - slot. This checks the response got a successful status code and, if it did, - calls \c parseXml() to consume the data. - - If the network reply gets an error, this is delivered to the \c error() - slot, which reports the error, clears the XML stream reader then disconnects - from the reply and deletes it. - - On completion (whether successful or otherwise) of a network reply, the \c - finished() slot restores the UI to be ready to accept a new URL to fetch by - re-enabling the line edit and "Fetch" button. - - \section2 The get() method - - \snippet serialization/rsslisting/rsslisting.cpp get - - The private \c get() method is used by the \c fetch() slot to initiate an - HTTP GET request. It first clears the XML stream reader and, if a reply is - currently active, disconnects and deletes it. If the URL it has been passed - is valid, it asks the network access manager to GET it. It connects its - relevant slots to signals of the resulting reply (if any) and sets up its - XML stream reader to read data from the reply - a network reply object is - also a \c QIODevice, from which data can be read. - - \section2 The parseXml() method - - \snippet serialization/rsslisting/rsslisting.cpp parse - - When data is received, and thus made available to the XML stream reader, \c - parseXml() reads from the XML stream, checking for \c item elements and, - within them, \c title and \c link elements. It will use the \c{rss:about} - attribute of an \c item as URL in the Link column of the tree-view, failing - that the content of its \c link element; and it uses the content of the \c - title element in the Title column of the tree-view. As each \c item element - closes, its details are turned into a new row in the tree widget, with the - extracted title and URL in the Title and Link columns. - - The variables that keep track of the parsing state - \c linkString, \c - titleString and \c currentTag - are member variables of the \c RSSListing - class, even though they are only accessed from this method, because this - method may be called repeatedly, as new data arrives, and one chunk of - received data may start an element that isn't completed until a later chunk - arrives. This enables the parser to operate asynchronously as the data - arrives, instead of having to wait until all the data has arrived. - - \sa QNetworkReply, QXmlStreamReader -*/ |