C++/Qt/QLabel

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Add a label and display

<source lang="cpp">

  1. include <QApplication>
  2. include <QLabel>

int main(int argc, char *argv[]) { 

   QApplication app(argc, argv);
   QLabel *label = new QLabel("Hello Qt!");
   label->show();
   return app.exec();

} 


 </source>


Adding image to QLabel

<source lang="cpp"> /****************************************************************************

    • 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.
    • $QT_BEGIN_LICENSE:LGPL$
    • Commercial Usage
    • Licensees holding valid Qt Commercial licenses may use this file in
    • accordance with the Qt Commercial License Agreement provided with the
    • Software or, alternatively, in accordance with the terms contained in
    • a written agreement between you and Nokia.
    • 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.
    • GNU General Public License Usage
    • Alternatively, this file may be used under the terms of the GNU
    • General Public License version 3.0 as published by the Free Software
    • Foundation and appearing in the file LICENSE.GPL included in the
    • packaging of this file. Please review the following information to
    • ensure the GNU General Public License version 3.0 requirements will be
    • met: http://www.gnu.org/copyleft/gpl.html.
    • If you have questions regarding the use of this file, please contact
    • Nokia at qt-info@nokia.com.
    • $QT_END_LICENSE$
                                                                                                                                                        • /
  1. include <QtGui>

int main(int argc, char *argv[]) { 

   QApplication app(argc, argv);
   QLabel topLevelLabel;
   QPixmap pixmap(":/images/tux.png");
   topLevelLabel.setPixmap(pixmap);
   topLevelLabel.setMask(pixmap.mask());
   topLevelLabel.show();
   return app.exec();

} 


 </source>


Clock label

<source lang="cpp"> Foundations of Qt Development\Chapter06\clocklabel\clocklabel.cpp /* 

* Copyright (c) 2006-2007, Johan Thelin
* 
* All rights reserved.
* 
* 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 APress 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.
*
*/
  1. include <QTimer>
  2. include <QTime>
  3. include "clocklabel.h"

ClockLabel::ClockLabel( QWidget *parent ) : QLabel( parent ) { 

 QTimer *timer = new QTimer( this );
 timer->setInterval( 1000 );
 connect( timer, SIGNAL(timeout()), this, SLOT(updateTime()) );
 timer->start();
 
 updateTime();

}

void ClockLabel::updateTime() { 

 setText( QTime::currentTime().toString( "hh:mm" ) );

}

Foundations of Qt Development\Chapter06\clocklabel\clocklabel.h /* 

* Copyright (c) 2006-2007, Johan Thelin
* 
* All rights reserved.
* 
* 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 APress 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.
*
*/
  1. ifndef CLOCKLABEL_H
  2. define CLOCKLABEL_H
  3. include <QLabel>

class ClockLabel : public QLabel { 

 Q_OBJECT

public: 

 ClockLabel( QWidget *parent = 0 );

private slots: 

 void updateTime();

};

  1. endif // CLOCKLABEL_H

Foundations of Qt Development\Chapter06\clocklabel\main.cpp /* 

* Copyright (c) 2006-2007, Johan Thelin
* 
* All rights reserved.
* 
* 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 APress 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.
*
*/
  1. include <QApplication>
  2. include "clocklabel.h"

int main( int argc, char **argv ) { 

 QApplication app( argc, argv );
 
 ClockLabel clock;
 clock.show();
 
 return app.exec();

} 


 </source>


Create a Label and show

<source lang="cpp">

  1. include <QApplication>
  2. include <QLabel>

int main(int argc, char *argv[]) { 

   QApplication a(argc, argv);
   QLabel label("Hello World");
   label.show();
   return a.exec();

} 


 </source>


Set QLabel buddy

<source lang="cpp"> /* 

* Copyright (c) 2006-2007, Johan Thelin
* 
* All rights reserved.
* 
* 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 APress 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.
*
*/
  1. include <QApplication>
  2. include <QDialog>
  3. include <QLineEdit>
  4. include <QLabel>
  5. include <QGridLayout>

int main( int argc, char **argv ) { 

 QApplication app( argc, argv );
 
 QDialog dlg;
 
 QLabel *fooLabel = new QLabel( "&Foo:" );
 QLabel *barLabel = new QLabel( "&Bar:" );
 QLineEdit *fooEdit = new QLineEdit();
 QLineEdit *barEdit = new QLineEdit();
 
 fooLabel->setBuddy( fooEdit );
 barLabel->setBuddy( barEdit );
 
 QGridLayout *layout = new QGridLayout( &dlg );
 layout->addWidget( fooLabel, 0, 0 );
 layout->addWidget( fooEdit, 0, 1 );
 layout->addWidget( barLabel, 1, 0 );
 layout->addWidget( barEdit, 1, 1 );
 dlg.show();
 
 return app.exec();

} 


 </source>


Set tooltip for QLabel

<source lang="cpp">

Foundations of Qt Development\Chapter09\statusbar\main.cpp /* 

* Copyright (c) 2006-2007, Johan Thelin
* 
* All rights reserved.
* 
* 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 APress 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.
*
*/
  1. include <QApplication>
  2. include <QMainWindow>
  3. include <QTextEdit>
  4. include <QStatusBar>
  5. include <QLabel>
  6. include <QProgressBar>

class MainWindow : public QMainWindow { public: 

 MainWindow();

}; MainWindow::MainWindow() : QMainWindow() { 

 setCentralWidget( new QTextEdit( this ) );
 QStatusBar *statusBar = this->statusBar();
 QProgressBar *progressBar = new QProgressBar();
 QLabel *mode = new QLabel( tr("  EDIT  ") );
 QLabel *modified = new QLabel( tr("  Y  ") );
 QLabel *size = new QLabel( tr("  999999kB  ") );
 mode->setMinimumSize( mode->sizeHint() );
 mode->setAlignment( Qt::AlignCenter );
 mode->setText( tr("EDIT") );
 mode->setToolTip( tr("The current working mode.") );
   
 statusBar->addPermanentWidget( mode );
 modified->setMinimumSize( modified->sizeHint() );
 modified->setAlignment( Qt::AlignCenter );
 modified->setText( tr("N") );
 modified->setToolTip( tr("Indicates if the current document has been modified or not.") );
 size->setMinimumSize( size->sizeHint() );
 size->setAlignment( Qt::AlignRight | Qt::AlignVCenter );
 size->setText( tr("%1kB ").arg(0) );
 size->setToolTip( tr("The memory used for the current document.") );
 
 progressBar->setTextVisible( false );
 progressBar->setRange( 0, 0 );
   
 statusBar->addWidget( progressBar, 1 );
 statusBar->addWidget( modified );
 statusBar->addWidget( size );
 statusBar->showMessage( tr("Ready"), 2000 );

} int main( int argc, char **argv ) { 

 QApplication app( argc, argv );
 
 
 MainWindow window;
 window.show();
 
 return app.exec();

} 


 </source>


Using HTML with QLabel

<source lang="cpp">

  1. include <QApplication>
  2. include <QMainWindow>
  3. include <QLabel>

int main(int argc, char *argv[]) { 

   QApplication a(argc, argv);
   QMainWindow mainWindow;
QLabel *label =new QLabel("
Central Widget
"); 
   mainWindow.setCentralWidget(label);
   mainWindow.show();
   return a.exec();

} 


 </source>
Источник — «http://cppe.ru/index.php?title=C%2B%2B/Qt/QLabel&oldid=1161»