<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>mainwindow.cpp Example File | Qt Widgets 5.12.2</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td >Qt 5.12</td><td ><a href="qtwidgets-index.html">Qt Widgets</a></td><td ><a href="qtwidgets-touch-fingerpaint-example.html">Finger Paint Example</a></td><td >mainwindow.cpp Example File</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right"><a href="qtwidgets-index.html">Qt 5.12.2 Reference Documentation</a></td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"><div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">mainwindow.cpp Example File</h1> <span class="subtitle">touch/fingerpaint/mainwindow.cpp</span> <!-- $$$touch/fingerpaint/mainwindow.cpp-description --> <div class="descr"> <a name="details"></a> <pre class="cpp"> <span class="comment">/**************************************************************************** ** ** Copyright (C) 2016 The Qt Company Ltd. ** Contact: https://www.qt.io/licensing/ ** ** This file is part of the examples of the Qt Toolkit. ** ** $QT_BEGIN_LICENSE:BSD$ ** 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. ** ** BSD License Usage ** Alternatively, 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 The Qt Company Ltd 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." ** ** $QT_END_LICENSE$ ** ****************************************************************************/</span> <span class="preprocessor">#include <QtWidgets></span> <span class="preprocessor">#include "mainwindow.h"</span> <span class="preprocessor">#include "scribblearea.h"</span> MainWindow<span class="operator">::</span>MainWindow() { scribbleArea <span class="operator">=</span> <span class="keyword">new</span> ScribbleArea; setCentralWidget(scribbleArea); createActions(); createMenus(); setWindowTitle(tr(<span class="string">"Finger Paint"</span>)); resize(<span class="number">500</span><span class="operator">,</span> <span class="number">500</span>); } <span class="type">void</span> MainWindow<span class="operator">::</span>closeEvent(<span class="type"><a href="../qtgui/qcloseevent.html">QCloseEvent</a></span> <span class="operator">*</span>event) { <span class="keyword">if</span> (maybeSave()) { event<span class="operator">-</span><span class="operator">></span>accept(); } <span class="keyword">else</span> { event<span class="operator">-</span><span class="operator">></span>ignore(); } } <span class="type">void</span> MainWindow<span class="operator">::</span>open() { <span class="keyword">if</span> (maybeSave()) { <span class="type"><a href="../qtcore/qstring.html">QString</a></span> fileName <span class="operator">=</span> <span class="type"><a href="qfiledialog.html">QFileDialog</a></span><span class="operator">::</span>getOpenFileName(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"Open File"</span>)<span class="operator">,</span> <span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>currentPath()); <span class="keyword">if</span> (<span class="operator">!</span>fileName<span class="operator">.</span>isEmpty()) scribbleArea<span class="operator">-</span><span class="operator">></span>openImage(fileName); } } <span class="type">void</span> MainWindow<span class="operator">::</span>save() { <span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>action <span class="operator">=</span> qobject_cast<span class="operator"><</span><span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span><span class="operator">></span>(sender()); <span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> fileFormat <span class="operator">=</span> action<span class="operator">-</span><span class="operator">></span>data()<span class="operator">.</span>toByteArray(); saveFile(fileFormat); } <span class="type">void</span> MainWindow<span class="operator">::</span>about() { <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>about(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"About Scribble"</span>)<span class="operator">,</span> tr(<span class="string">"<p>The <b>Scribble</b> example shows how to use QMainWindow as the "</span> <span class="string">"base widget for an application, and how to reimplement some of "</span> <span class="string">"QWidget's event handlers to receive the events generated for "</span> <span class="string">"the application's widgets:</p><p> We reimplement the mouse event "</span> <span class="string">"handlers to facilitate drawing, the paint event handler to "</span> <span class="string">"update the application and the resize event handler to optimize "</span> <span class="string">"the application's appearance. In addition we reimplement the "</span> <span class="string">"close event handler to intercept the close events before "</span> <span class="string">"terminating the application.</p><p> The example also demonstrates "</span> <span class="string">"how to use QPainter to draw an image in real time, as well as "</span> <span class="string">"to repaint widgets.</p>"</span>)); } <span class="type">void</span> MainWindow<span class="operator">::</span>createActions() { openAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&Open..."</span>)<span class="operator">,</span> <span class="keyword">this</span>); openAct<span class="operator">-</span><span class="operator">></span>setShortcut(tr(<span class="string">"Ctrl+O"</span>)); connect(openAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(open())); foreach (<span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> format<span class="operator">,</span> <span class="type"><a href="../qtgui/qimagewriter.html">QImageWriter</a></span><span class="operator">::</span>supportedImageFormats()) { <span class="type"><a href="../qtcore/qstring.html">QString</a></span> text <span class="operator">=</span> tr(<span class="string">"%1..."</span>)<span class="operator">.</span>arg(<span class="type"><a href="../qtcore/qstring.html">QString</a></span>(format)<span class="operator">.</span>toUpper()); <span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>action <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(text<span class="operator">,</span> <span class="keyword">this</span>); action<span class="operator">-</span><span class="operator">></span>setData(format); connect(action<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(save())); saveAsActs<span class="operator">.</span>append(action); } printAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&Print..."</span>)<span class="operator">,</span> <span class="keyword">this</span>); connect(printAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> scribbleArea<span class="operator">,</span> SLOT(print())); exitAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"E&xit"</span>)<span class="operator">,</span> <span class="keyword">this</span>); exitAct<span class="operator">-</span><span class="operator">></span>setShortcut(tr(<span class="string">"Ctrl+Q"</span>)); connect(exitAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(close())); clearScreenAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&Clear Screen"</span>)<span class="operator">,</span> <span class="keyword">this</span>); clearScreenAct<span class="operator">-</span><span class="operator">></span>setShortcut(tr(<span class="string">"Ctrl+L"</span>)); connect(clearScreenAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> scribbleArea<span class="operator">,</span> SLOT(clearImage())); aboutAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"&About"</span>)<span class="operator">,</span> <span class="keyword">this</span>); connect(aboutAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(about())); aboutQtAct <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qaction.html">QAction</a></span>(tr(<span class="string">"About &Qt"</span>)<span class="operator">,</span> <span class="keyword">this</span>); connect(aboutQtAct<span class="operator">,</span> SIGNAL(triggered())<span class="operator">,</span> <a href="qapplication.html#qApp">qApp</a><span class="operator">,</span> SLOT(aboutQt())); } <span class="type">void</span> MainWindow<span class="operator">::</span>createMenus() { saveAsMenu <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qmenu.html">QMenu</a></span>(tr(<span class="string">"&Save As"</span>)<span class="operator">,</span> <span class="keyword">this</span>); foreach (<span class="type"><a href="qaction.html">QAction</a></span> <span class="operator">*</span>action<span class="operator">,</span> saveAsActs) saveAsMenu<span class="operator">-</span><span class="operator">></span>addAction(action); fileMenu <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qmenu.html">QMenu</a></span>(tr(<span class="string">"&File"</span>)<span class="operator">,</span> <span class="keyword">this</span>); fileMenu<span class="operator">-</span><span class="operator">></span>addAction(openAct); fileMenu<span class="operator">-</span><span class="operator">></span>addMenu(saveAsMenu); fileMenu<span class="operator">-</span><span class="operator">></span>addAction(printAct); fileMenu<span class="operator">-</span><span class="operator">></span>addSeparator(); fileMenu<span class="operator">-</span><span class="operator">></span>addAction(exitAct); optionMenu <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qmenu.html">QMenu</a></span>(tr(<span class="string">"&Options"</span>)<span class="operator">,</span> <span class="keyword">this</span>); optionMenu<span class="operator">-</span><span class="operator">></span>addAction(clearScreenAct); helpMenu <span class="operator">=</span> <span class="keyword">new</span> <span class="type"><a href="qmenu.html">QMenu</a></span>(tr(<span class="string">"&Help"</span>)<span class="operator">,</span> <span class="keyword">this</span>); helpMenu<span class="operator">-</span><span class="operator">></span>addAction(aboutAct); helpMenu<span class="operator">-</span><span class="operator">></span>addAction(aboutQtAct); menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(fileMenu); menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(optionMenu); menuBar()<span class="operator">-</span><span class="operator">></span>addMenu(helpMenu); } bool MainWindow<span class="operator">::</span>maybeSave() { <span class="keyword">if</span> (scribbleArea<span class="operator">-</span><span class="operator">></span>isModified()) { <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>StandardButton ret; ret <span class="operator">=</span> <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>warning(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"Scribble"</span>)<span class="operator">,</span> tr(<span class="string">"The image has been modified.\n"</span> <span class="string">"Do you want to save your changes?"</span>)<span class="operator">,</span> <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>Save <span class="operator">|</span> <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>Discard <span class="operator">|</span> <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>Cancel); <span class="keyword">if</span> (ret <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>Save) { <span class="keyword">return</span> saveFile(<span class="string">"png"</span>); } <span class="keyword">else</span> <span class="keyword">if</span> (ret <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qmessagebox.html">QMessageBox</a></span><span class="operator">::</span>Cancel) { <span class="keyword">return</span> <span class="keyword">false</span>; } } <span class="keyword">return</span> <span class="keyword">true</span>; } bool MainWindow<span class="operator">::</span>saveFile(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> <span class="operator">&</span>fileFormat) { <span class="type"><a href="../qtcore/qstring.html">QString</a></span> initialPath <span class="operator">=</span> <span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>currentPath() <span class="operator">+</span> <span class="string">"/untitled."</span> <span class="operator">+</span> fileFormat; <span class="type"><a href="../qtcore/qstring.html">QString</a></span> fileName <span class="operator">=</span> <span class="type"><a href="qfiledialog.html">QFileDialog</a></span><span class="operator">::</span>getSaveFileName(<span class="keyword">this</span><span class="operator">,</span> tr(<span class="string">"Save As"</span>)<span class="operator">,</span> initialPath<span class="operator">,</span> tr(<span class="string">"%1 Files (*.%2);;All Files (*)"</span>) <span class="operator">.</span>arg(<span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">::</span>fromLatin1(fileFormat<span class="operator">.</span>toUpper())) <span class="operator">.</span>arg(<span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">::</span>fromLatin1(fileFormat))); <span class="keyword">if</span> (fileName<span class="operator">.</span>isEmpty()) { <span class="keyword">return</span> <span class="keyword">false</span>; } <span class="keyword">else</span> { <span class="keyword">return</span> scribbleArea<span class="operator">-</span><span class="operator">></span>saveImage(fileName<span class="operator">,</span> fileFormat<span class="operator">.</span>constData()); } } </pre> </div> <!-- @@@touch/fingerpaint/mainwindow.cpp --> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2019 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br/> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br/> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. </p> </div> </body> </html>