Image Composition Example | Qt Widgets 5.13.0

Qt 5.13 | Qt Widgets | Image Composition Example

Qt 5.13.0 Reference Documentation

# Image Composition Example

      /****************************************************************************
      **
      ** 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."
      **
      ** $QT_END_LICENSE$
      **
      ****************************************************************************/

      #include "imagecomposer.h"

      #include <QtWidgets>

      static const QSize resultSize(200, 200);

      ImageComposer::ImageComposer()
      {
          sourceButton = new QToolButton;
          sourceButton->setIconSize(resultSize);

          operatorComboBox = new QComboBox;
          addOp(QPainter::CompositionMode_SourceOver, tr("SourceOver"));
          addOp(QPainter::CompositionMode_DestinationOver, tr("DestinationOver"));
          addOp(QPainter::CompositionMode_Clear, tr("Clear"));
          addOp(QPainter::CompositionMode_Source, tr("Source"));
          addOp(QPainter::CompositionMode_Destination, tr("Destination"));
          addOp(QPainter::CompositionMode_SourceIn, tr("SourceIn"));
          addOp(QPainter::CompositionMode_DestinationIn, tr("DestinationIn"));
          addOp(QPainter::CompositionMode_SourceOut, tr("SourceOut"));
          addOp(QPainter::CompositionMode_DestinationOut, tr("DestinationOut"));
          addOp(QPainter::CompositionMode_SourceAtop, tr("SourceAtop"));
          addOp(QPainter::CompositionMode_DestinationAtop, tr("DestinationAtop"));
          addOp(QPainter::CompositionMode_Xor, tr("Xor"));
          addOp(QPainter::CompositionMode_Plus, tr("Plus"));
          addOp(QPainter::CompositionMode_Multiply, tr("Multiply"));
          addOp(QPainter::CompositionMode_Screen, tr("Screen"));
          addOp(QPainter::CompositionMode_Overlay, tr("Overlay"));
          addOp(QPainter::CompositionMode_Darken, tr("Darken"));
          addOp(QPainter::CompositionMode_Lighten, tr("Lighten"));
          addOp(QPainter::CompositionMode_ColorDodge, tr("ColorDodge"));
          addOp(QPainter::CompositionMode_ColorBurn, tr("ColorBurn"));
          addOp(QPainter::CompositionMode_HardLight, tr("HardLight"));
          addOp(QPainter::CompositionMode_SoftLight, tr("SoftLight"));
          addOp(QPainter::CompositionMode_Difference, tr("Difference"));
          addOp(QPainter::CompositionMode_Exclusion, tr("Exclusion"));

          destinationButton = new QToolButton;
          destinationButton->setIconSize(resultSize);

          equalLabel = new QLabel(tr("="));

          resultLabel = new QLabel;
          resultLabel->setMinimumWidth(resultSize.width());

          connect(sourceButton, &QAbstractButton::clicked,
                  this, &ImageComposer::chooseSource);
          connect(operatorComboBox, QOverload<int>::of(&QComboBox::activated),
                  this, &ImageComposer::recalculateResult);
          connect(destinationButton, &QAbstractButton::clicked,
                  this, &ImageComposer::chooseDestination);

          QGridLayout *mainLayout = new QGridLayout;
          mainLayout->addWidget(sourceButton, 0, 0, 3, 1);
          mainLayout->addWidget(operatorComboBox, 1, 1);
          mainLayout->addWidget(destinationButton, 0, 2, 3, 1);
          mainLayout->addWidget(equalLabel, 1, 3);
          mainLayout->addWidget(resultLabel, 0, 4, 3, 1);
          mainLayout->setSizeConstraint(QLayout::SetFixedSize);
          setLayout(mainLayout);

          resultImage = QImage(resultSize, QImage::Format_ARGB32_Premultiplied);

          loadImage(":/images/butterfly.png", &sourceImage, sourceButton);
          loadImage(":/images/checker.png", &destinationImage, destinationButton);

          setWindowTitle(tr("Image Composition"));
      }

      void ImageComposer::chooseSource()
      {
          chooseImage(tr("Choose Source Image"), &sourceImage, sourceButton);
      }

      void ImageComposer::chooseDestination()
      {
          chooseImage(tr("Choose Destination Image"), &destinationImage, destinationButton);
      }

      void ImageComposer::recalculateResult()
      {
          QPainter::CompositionMode mode = currentMode();

          QPainter painter(&resultImage);
          painter.setCompositionMode(QPainter::CompositionMode_Source);
          painter.fillRect(resultImage.rect(), Qt::transparent);
          painter.setCompositionMode(QPainter::CompositionMode_SourceOver);
          painter.drawImage(0, 0, destinationImage);
          painter.setCompositionMode(mode);
          painter.drawImage(0, 0, sourceImage);
          painter.setCompositionMode(QPainter::CompositionMode_DestinationOver);
          painter.fillRect(resultImage.rect(), Qt::white);
          painter.end();

          resultLabel->setPixmap(QPixmap::fromImage(resultImage));
      }

      void ImageComposer::addOp(QPainter::CompositionMode mode, const QString &name)
      {
          operatorComboBox->addItem(name, mode);
      }

      void ImageComposer::chooseImage(const QString &title, QImage *image,
                                      QToolButton *button)
      {
          QString fileName = QFileDialog::getOpenFileName(this, title);
          if (!fileName.isEmpty())
              loadImage(fileName, image, button);
      }

      void ImageComposer::loadImage(const QString &fileName, QImage *image,
                                    QToolButton *button)
      {
          image->load(fileName);

          // Scale the image to given size
          *image = image->scaled(resultSize, Qt::KeepAspectRatio);

          QImage fixedImage(resultSize, QImage::Format_ARGB32_Premultiplied);
          QPainter painter(&fixedImage);
          painter.setCompositionMode(QPainter::CompositionMode_Source);
          painter.fillRect(fixedImage.rect(), Qt::transparent);
          painter.setCompositionMode(QPainter::CompositionMode_SourceOver);
          painter.drawImage(imagePos(*image), *image);
          painter.end();
          button->setIcon(QPixmap::fromImage(fixedImage));

          *image = fixedImage;

          recalculateResult();
      }

      QPainter::CompositionMode ImageComposer::currentMode() const
      {
          return (QPainter::CompositionMode)
                 operatorComboBox->itemData(operatorComboBox->currentIndex()).toInt();
      }

      QPoint ImageComposer::imagePos(const QImage &image) const
      {
          return QPoint((resultSize.width() - image.width()) / 2,
                        (resultSize.height() - image.height()) / 2);
      }