be15856f61
Change copyrights and license headers from Nokia to Digia Change-Id: If1cc974286d29fd01ec6c19dd4719a67f4c3f00e Reviewed-by: Lars Knoll <lars.knoll@digia.com> Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
160 lines
6.7 KiB
Plaintext
160 lines
6.7 KiB
Plaintext
/****************************************************************************
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**
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** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/legal
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**
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** This file is part of the documentation of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:FDL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and Digia. For licensing terms and
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** conditions see http://qt.digia.com/licensing. For further information
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** use the contact form at http://qt.digia.com/contact-us.
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**
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** GNU Free Documentation License Usage
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** Alternatively, this file may be used under the terms of the GNU Free
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** Documentation License version 1.3 as published by the Free Software
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** Foundation and appearing in the file included in the packaging of
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** this file. Please review the following information to ensure
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** the GNU Free Documentation License version 1.3 requirements
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** will be met: http://www.gnu.org/copyleft/fdl.html.
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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/*!
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\example uitools/textfinder
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\title Text Finder Example
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The Text Finder example demonstrates how to dynamically process forms
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using the QtUiTools module. Dynamic form processing enables a form to
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be processed at run-time only by changing the UI file for the project.
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The program allows the user to look up a particular word within the
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contents of a text file. This text file is included in the project's
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resource and is loaded into the display at startup.
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\table
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\row \li \inlineimage textfinder-example-find.png
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\li \inlineimage textfinder-example-find2.png
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\endtable
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\section1 Setting Up The Resource File
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The resources required for Text Finder are:
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\list
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\li \e{textfinder.ui} - the user interface file created in QtDesigner
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\li \e{input.txt} - a text file containing some text to be displayed
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in the QTextEdit
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\endlist
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\e{textfinder.ui} contains all the necessary QWidget objects for the
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Text Finder. A QLineEdit is used for the user input, a QTextEdit is
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used to display the contents of \e{input.txt}, a QLabel is used to
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display the text "Keyword", and a QPushButton is used for the "Find"
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button. The screenshot below shows the preview obtained in QtDesigner.
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\image textfinder-example-userinterface.png
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A \e{textfinder.qrc} file is used to store both the \e{textfinder.ui}
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and \e{input.txt} in the application's executable. The file contains
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the following code:
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\quotefile examples/uitools/textfinder/textfinder.qrc
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For more information on resource files, see \l{The Qt Resource System}.
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To generate a form at run-time, the example is linked against the
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QtUiTools module library. This is done in the \c{textfinder.pro} file
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that contains the following lines:
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\snippet doc/src/snippets/code/doc_src_examples_textfinder.pro 0
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\section1 TextFinder Class Definition
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The \c TextFinder class is a subclass of QWidget and it hosts the
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\l{QWidget}s we need to access in the user interface. The QLabel in the
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user interface is not declared here as we do not need to access it.
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\snippet examples/uitools/textfinder/textfinder.h 0
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The slot \c{on_findButton_clicked()} is a slot named according to the
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\l{Using a Designer UI File in Your Application#Automatic Connections}
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{Automatic Connection} naming convention required
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by \c uic.
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\section1 TextFinder Class Implementation
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The \c TextFinder class's constructor calls the \c loadUiFile() function
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and then uses \c qFindChild() to access the user interface's
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\l{QWidget}s.
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\snippet examples/uitools/textfinder/textfinder.cpp 0
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We then use QMetaObject's system to enable signal and slot connections.
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\snippet examples/uitools/textfinder/textfinder.cpp 2
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The loadTextFile() function is called to load \c{input.txt} into
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QTextEdit to displays its contents.
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\snippet examples/uitools/textfinder/textfinder.cpp 3a
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The \c{TextFinder}'s layout is set with \l{QWidget::}{setLayout()}.
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\snippet examples/uitools/textfinder/textfinder.cpp 3b
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Finally, the window title is set to \e {Text Finder} and \c isFirstTime is
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set to true.
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\c isFirstTime is used as a flag to indicate whether the search operation
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has been performed more than once. This is further explained with the
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\c{on_findButton_clicked()} function.
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The \c{loadUiFile()} function is used to load the user interface file
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previously created in QtDesigner. The QUiLoader class is instantiated
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and its \c load() function is used to load the form into \c{formWidget}
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that acts as a place holder for the user interface. The function then
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returns \c{formWidget} to its caller.
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\snippet examples/uitools/textfinder/textfinder.cpp 4
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As mentioned earlier, the loadTextFile() function loads \e{input.txt}
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into QTextEdit to display its contents. Data is read using QTextStream
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into a QString object, \c line with the QTextStream::readAll() function.
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The contents of \c line are then appended to \c{ui_textEdit}.
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\snippet examples/uitools/textfinder/textfinder.cpp 5
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The \c{on_findButton_clicked()} function is a slot that is connected to
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\c{ui_findButton}'s \c clicked() signal. The \c searchString is extracted
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from the \c ui_lineEdit and the \c document is extracted from \c textEdit.
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In event there is an empty \c searchString, a QMessageBox is used,
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requesting the user to enter a word. Otherwise, we traverse through the
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words in \c ui_textEdit, and highlight all ocurrences of the
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\c searchString . Two QTextCursor objects are used: One to traverse through
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the words in \c line and another to keep track of the edit blocks.
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\snippet examples/uitools/textfinder/textfinder.cpp 7
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The \c isFirstTime flag is set to false the moment \c findButton is
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clicked. This is necessary to undo the previous text highlight before
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highlighting the user's next search string. Also, the \c found flag
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is used to indicate if the \c searchString was found within the contents
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of \c ui_textEdit. If it was not found, a QMessageBox is used
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to inform the user.
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\snippet examples/uitools/textfinder/textfinder.cpp 9
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\section1 \c main() Function
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\snippet examples/uitools/textfinder/main.cpp 0
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The \c main() function initialises the \e{textfinder.qrc} resource file
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and instantiates as well as displays \c TextFinder.
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\sa {Calculator Builder Example}, {World Time Clock Builder Example}
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*/
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