Qt 5.11 | Qt Widgets | Image Composition Example | imagecomposer.cpp Example File

Qt 5.11.3 Reference Documentation

# imagecomposer.cpp Example File

painting/imagecomposition/imagecomposer.cpp

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      #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, SIGNAL(clicked()), this, SLOT(chooseSource()));
          connect(operatorComboBox, SIGNAL(activated(int)), this, SLOT(recalculateResult()));
          connect(destinationButton, SIGNAL(clicked()), this, SLOT(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);
      }