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-/****************************************************************************
-**
-** Copyright (C) 2016 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the documentation of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:FDL$
-** 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 The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU Free Documentation License Usage
-** Alternatively, this file may be used under the terms of the GNU Free
-** Documentation License version 1.3 as published by the Free Software
-** Foundation and appearing in the file included in the packaging of
-** this file. Please review the following information to ensure
-** the GNU Free Documentation License version 1.3 requirements
-** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-/*!
- \example googlesuggest
- \title Google Suggest Example
- \ingroup examples-network
- \brief Obtains the list of search recommendations by the Google search engine.
-
- The example uses the QNetworkAccessManager to obtain the list of search
- recommendations by Google as the user types into a QLineEdit.
-
- \image googlesuggest-example.png
-
- The application makes use of the \c get function in
- QNetworkAccessManager to post a request and obtain the result of the search
- query sent to the Google search engine. The results returned are listed as
- clickable links appearing below the search box as a drop-down menu.
-
- The widget is built up by a QLineEdit as the search box, and a QTreeView
- used as a popup menu below the search box.
-
- \section1 GSuggestCompletion Class Declaration
-
- This class implements an event filter and a number of functions to display
- the search results and to determent when and how to perform the search.
-
- \snippet googlesuggest/googlesuggest.h 1
-
- The class connects to a QLineEdit and uses a QTreeWidget to display the
- results. A QTimer controls the start of the network requests that are
- executed using a QNetworkAccessManager.
-
- \section1 GSuggestCompletion Class Implementation
-
- We start by defining a constant containing the URL to be used in the Google
- queries. This is the basis for the query. The letters typed into the search
- box will be added to the query to perform the search itself.
-
- \snippet googlesuggest/googlesuggest.cpp 1
-
- In the constructor, we set the parent of this GSuggestCompletion instance
- to be the QLineEdit passed in. For simplicity, the QLineEdit is also stored
- in the explicit \c editor member variable.
-
- We then create a QTreeWidget as a toplevel widget and configure the various
- properties to give it the look of a popup widget. The widget is populated
- with the results by Google Suggest API request.
-
- Furthermore, we install the GSuggestCompletion instance as an event filter
- on the QTreeWidget, and connect the \c itemClicked() signal with the \c
- doneCompletion() slot.
-
- A single-shot QTimer is used to start the request when the user has stopped
- typing for 500 ms.
-
- Finally, we connect the networkManagers \c finished() signal with the \c
- handleNetworkData() slot to handle the incoming data.
-
- \snippet googlesuggest/googlesuggest.cpp 2
-
- Since the QTreeWidget popup has been instantiated as a toplevel widget, the
- destructor has to delete it explicitly from memory to avoid a memory leak.
-
- \snippet googlesuggest/googlesuggest.cpp 3
-
- The event filter handles mouse press and key press events that are
- delivered to the popup. For mouse press events we just hide the popup and
- return focus to the editor widget, and then return true to prevent further
- event processing.
-
- Key event handling is implemented so that Enter and Return execute the
- selected link, while the Escape key hides the popup. Since we want to be
- able to navigate the list of suggestions using the different navigation
- keys on the keyboard we let Qt continue regular event processing for those
- by returning false from the eventFilter reimplementation.
-
- For all other keys, the event will be passed on to the editor widget and the
- popup is hidden. This way the user's typing will not be interrupted by the
- popping up of the completion list.
-
- \snippet googlesuggest/googlesuggest.cpp 4
-
- The \c showCompletion() function populates the QTreeWidget with the results
- returned from the query. It takes a QStringList of the suggested search
- terms.
-
- \snippet googlesuggest/googlesuggest.cpp 5
-
- A QTreeWidgetItem is created for each index in the list and inserted into
- the QTreeWidget. Finally, we adjust position and size of the popup to make
- sure that it pops up in the correct position below the editor, and show it.
-
- The \c doneCompletion() function, which is called by the event filter when
- either Enter or Return keys are pressed, stops the timer to prevent further
- requests and passes the text of the selected item to the editor. We then
- make the \c editor QLineEdit emit the returnPressed() signal, to which the
- application can connect to open the respective web page.
-
- \snippet googlesuggest/googlesuggest.cpp 6
-
- The \c autoSuggest() slot is called when the timer times out, and uses the
- text in the editor to build the complete search query. The query is then
- passed to the QNetworkAccessManager's \c get() function to start the
- request.
-
- \snippet googlesuggest/googlesuggest.cpp 7
-
- The function \c preventSuggest() stops the timer to prevent further
- requests from being started.
-
- \snippet googlesuggest/googlesuggest.cpp 8
-
- When the network request is finished, the QNetworkAccessManager delivers the
- data received from the server through the networkReply object.
-
- \snippet googlesuggest/googlesuggest.cpp 9
-
- To extract the data from the reply we use the \c readAll() function, which
- is inherited from QIODevice and returns a QByteArray. Since this data is
- encoded in XML we can use a QXmlStreamReader to traverse the data and
- extract the search result as QStrings, which we can stream into two
- QStringLists used to populate the popup.
-
- Finally, we schedule the QNetworkReply object for deletion using the \c
- deleteLater function.
-
- \section1 SearchBox Class Declaration
-
- The SearchBox class inherits QLineEdit and adds the protected slot \c
- doSearch().
-
- A \c GSuggestCompletion member provides the SearchBox with the request
- functionality and the suggestions returned from the Google search engine.
-
- \snippet googlesuggest/searchbox.h 1
-
- \section1 SearchBox Class Implementation
-
- The search box constructor instantiates the GSuggestCompletion object and
- connects the returnPressed() signal to the doSearch() slot.
-
- \snippet googlesuggest/searchbox.cpp 1
-
- The function \c doSearch() stops the completer from sending any further
- queries to the search engine.
-
- Further, the function extracts the selected search phrase and opens it
- in the default web browser using QDesktopServices.
-
- \snippet googlesuggest/searchbox.cpp 2
-
-*/