--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/doc/src/examples/findfiles.qdoc Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,263 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+ \example dialogs/findfiles
+ \title Find Files Example
+
+ The Find Files example shows how to use QProgressDialog to provide
+ feedback on the progress of a slow operation. The example also
+ shows how to use QFileDialog to facilitate browsing, how to use
+ QTextStream's streaming operators to read a file, and how to use
+ QTableWidget to provide standard table display facilities for
+ applications. In addition, files can be opened using the
+ QDesktopServices class.
+
+ \image findfiles-example.png Screenshot of the Find Files example
+
+ With the Find Files application the user can search for files in a
+ specified directory, matching a specified file name (using wild
+ cards if appropiate) and containing a specified text.
+
+ The user is provided with a \gui Browse option, and the result of
+ the search is displayed in a table with the names of the files
+ found and their sizes. In addition the application provides a
+ total count of the files found.
+
+ \section1 Window Class Definition
+
+ The \c Window class inherits QWidget, and is the main application
+ widget. It shows the search options, and displays the search
+ results.
+
+ \snippet examples/dialogs/findfiles/window.h 0
+
+ We need two private slots: The \c browse() slot is called whenever
+ the user wants to browse for a directory to search in, and the \c
+ find() slot is called whenever the user requests a search to be
+ performed by pressing the \gui Find button.
+
+ In addition we declare several private functions: We use the \c
+ findFiles() function to search for files matching the user's
+ specifications, we call the \c showFiles() function to display the
+ results, and we use \c createButton(), \c createComboBox() and \c
+ createFilesTable() when we are constructing the widget.
+
+ \section1 Window Class Implementation
+
+ In the constructor we first create the application's widgets.
+
+ \snippet examples/dialogs/findfiles/window.cpp 0
+
+ We create the application's buttons using the private \c
+ createButton() function. Then we create the comboboxes associated
+ with the search specifications, using the private \c
+ createComboBox() function. We also create the application's labels
+ before we use the private \c createFilesTable() function to create
+ the table displaying the search results.
+
+ \snippet examples/dialogs/findfiles/window.cpp 1
+
+ Then we add all the widgets to a main layout using QGridLayout. We
+ have, however, put the \c Find and \c Quit buttons and a
+ stretchable space in a separate QHBoxLayout first, to make the
+ buttons appear in the \c Window widget's bottom right corner.
+
+ \snippet examples/dialogs/findfiles/window.cpp 2
+
+ The \c browse() slot presents a file dialog to the user, using the
+ QFileDialog class. QFileDialog enables a user to traverse the file
+ system in order to select one or many files or a directory. The
+ easiest way to create a QFileDialog is to use the convenience
+ static functions.
+
+ Here we use the static QFileDialog::getExistingDirectory()
+ function which returns an existing directory selected by the
+ user. Then we display the directory in the directory combobox
+ using the QComboBox::addItem() function, and updates the current
+ index.
+
+ QComboBox::addItem() adds an item to the combobox with the given
+ text (if it is not already present in the list), and containing
+ the specified userData. The item is appended to the list of
+ existing items.
+
+ \snippet examples/dialogs/findfiles/window.cpp 3
+
+ The \c find() slot is called whenever the user requests a new
+ search by pressing the \gui Find button.
+
+ First we eliminate any previous search results by setting the
+ table widgets row count to zero. Then we retrieve the
+ specified file name, text and directory path from the respective
+ comboboxes.
+
+ \snippet examples/dialogs/findfiles/window.cpp 4
+
+ We use the directory's path to create a QDir; the QDir class
+ provides access to directory structures and their contents. We
+ create a list of the files (contained in the newly created QDir)
+ that match the specified file name. If the file name is empty
+ the list will contain all the files in the directory.
+
+ Then we search through all the files in the list, using the private
+ \c findFiles() function, eliminating the ones that don't contain
+ the specified text. And finally, we display the results using the
+ private \c showFiles() function.
+
+ If the user didn't specify any text, there is no reason to search
+ through the files, and we display the results immediately.
+
+ \image findfiles_progress_dialog.png Screenshot of the Progress Dialog
+
+ \snippet examples/dialogs/findfiles/window.cpp 5
+
+ In the private \c findFiles() function we search through a list of
+ files, looking for the ones that contain a specified text. This
+ can be a very slow operation depending on the number of files as
+ well as their sizes. In case there are a large number of files, or
+ there exists some large files on the list, we provide a
+ QProgressDialog.
+
+ The QProgressDialog class provides feedback on the progress of a
+ slow operation. It is used to give the user an indication of how
+ long an operation is going to take, and to demonstrate that the
+ application has not frozen. It can also give the user an
+ opportunity to abort the operation.
+
+ \snippet examples/dialogs/findfiles/window.cpp 6
+
+ We run through the files, one at a time, and for each file we
+ update the QProgressDialog value. This property holds the current
+ amount of progress made. We also update the progress dialog's
+ label.
+
+ Then we call the QCoreApplication::processEvents() function using
+ the QApplication object. In this way we interleave the display of
+ the progress made with the process of searching through the files
+ so the application doesn't appear to be frozen.
+
+ The QApplication class manages the GUI application's control flow
+ and main settings. It contains the main event loop, where all
+ events from the window system and other sources are processed and
+ dispatched. QApplication inherits QCoreApplication. The
+ QCoreApplication::processEvents() function processes all pending
+ events according to the specified QEventLoop::ProcessEventFlags
+ until there are no more events to process. The default flags are
+ QEventLoop::AllEvents.
+
+ \snippet examples/dialogs/findfiles/window.cpp 7
+
+ After updating the QProgressDialog, we create a QFile using the
+ QDir::absoluteFilePath() function which returns the absolute path
+ name of a file in the directory. We open the file in read-only
+ mode, and read one line at a time using QTextStream.
+
+ The QTextStream class provides a convenient interface for reading
+ and writing text. Using QTextStream's streaming operators, you can
+ conveniently read and write words, lines and numbers.
+
+ For each line we read we check if the QProgressDialog has been
+ canceled. If it has, we abort the operation, otherwise we check if
+ the line contains the specified text. When we find the text within
+ one of the files, we add the file's name to a list of found files
+ that contain the specified text, and start searching a new file.
+
+ Finally, we return the list of the files found.
+
+ \snippet examples/dialogs/findfiles/window.cpp 8
+
+ Both the \c findFiles() and \c showFiles() functions are called from
+ the \c find() slot. In the \c showFiles() function we run through
+ the provided list of file names, adding each file name to the
+ first column in the table widget and retrieving the file's size using
+ QFile and QFileInfo for the second column.
+
+ We also update the total number of files found.
+
+ \snippet examples/dialogs/findfiles/window.cpp 9
+
+ The private \c createButton() function is called from the
+ constructor. We create a QPushButton with the provided text,
+ connect it to the provided slot, and return a pointer to the
+ button.
+
+ \snippet examples/dialogs/findfiles/window.cpp 10
+
+ The private \c createComboBox() function is also called from the
+ contructor. We create a QComboBox with the given text, and make it
+ editable.
+
+ When the user enters a new string in an editable combobox, the
+ widget may or may not insert it, and it can insert it in several
+ locations, depending on the QComboBox::InsertPolicy. The default
+ policy is is QComboBox::InsertAtBottom.
+
+ Then we add the provided text to the combobox, and specify the
+ widget's size policies, before we return a pointer to the
+ combobox.
+
+ \snippet examples/dialogs/findfiles/window.cpp 11
+
+ The private \c createFilesTable() function is called from the
+ constructor. In this function we create the QTableWidget that
+ will display the search results. We set its horizontal headers and
+ their resize mode.
+
+ QTableWidget inherits QTableView which provides a default
+ model/view implementation of a table view. The
+ QTableView::horizontalHeader() function returns the table view's
+ horizontal header as a QHeaderView. The QHeaderView class provides
+ a header row or header column for item views, and the
+ QHeaderView::setResizeMode() function sets the constraints on how
+ the section in the header can be resized.
+
+ Finally, we hide the QTableWidget's vertical headers using the
+ QWidget::hide() function, and remove the default grid drawn for
+ the table using the QTableView::setShowGrid() function.
+
+ \snippet examples/dialogs/findfiles/window.cpp 12
+
+ The \c openFileOfItem() slot is invoked when the user double
+ clicks on a cell in the table. The QDesktopServices::openUrl()
+ knows how to open a file given the file name.
+*/
+