QImage Rotation and Translation & Invert Specific Colors

[karankumar1609]

You require to set a result image on QLabel..
The better way to do this, is have a result image and paint on it (Outside the paint event).
After loading of primaryImage and secondaryImage you can do your calculations on images and create a result image

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::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));
}

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the above code is the part of the Image Composition Example

As per your program need you have to look at the Image Composition Example