Question

I am trying to run slightly modified code from the Qt fluidLauncher demo that shows a slideshow. The code is pasted in below. When the paintEvent is handled a black rectangle is shown on the screen because the imported image size is 0.

Single stepping through the code in Qt creator, the currentImagePath is ‘”/home/tim/Pictures/HPIM0406.JPG”‘ in the watch window. The path is correct including the case and / dividers. The ‘slide’ variable always shows <not accessible>.

At the point in the code where slideSize = slide.size() the slide size changes from (8481696,0) to (0,0). It appears that although no error is thrown, the QPixmap slide (currentImagePath); is not retrieving the image.

void SlideShow::paintEvent(QPaintEvent *event)
{
 QPainter painter(this);
 QString currentImagePath;

 painter.setRenderHint(QPainter::Antialiasing, false);

 if (d->imagePaths.size() > 0) {
    currentImagePath = d->imagePaths[d->currentSlide];
     QPixmap slide( currentImagePath );
     QSize slideSize = slide.size();
     QSize scaledSize = QSize(qMin(slideSize.width(), size().width()),
         qMin(slideSize.height(), size().height()));
     if (slideSize != scaledSize)
         slide = slide.scaled(scaledSize, Qt::KeepAspectRatio);

     QRect pixmapRect(qMax( (size().width() - slide.width())/2, 0),
                      qMax( (size().height() - slide.height())/2, 0),
                      slide.width(),
                      slide.height());

     if (pixmapRect.top() > 0) {
         // Fill in top & bottom rectangles:
         painter.fillRect(0, 0, size().width(), pixmapRect.top(), Qt::black);
         painter.fillRect(0, pixmapRect.bottom(), size().width(), size().height(), Qt::black);
     }

     if (pixmapRect.left() > 0) {
         // Fill in left & right rectangles:
         painter.fillRect(0, 0, pixmapRect.left(), size().height(), Qt::black);
         painter.fillRect(pixmapRect.right(), 0, size().width(), size().height(), Qt::black);
     }

     painter.drawPixmap(pixmapRect, slide);

 } else
     painter.fillRect(event->rect(), Qt::black);

}

I’ve struggled with the problem for most of the evening. Can anyone suggest additional code that I could add for debugging or let me know what may be wrong with this code?

Answer 1

I’ve some idea for solving your problem:

1. You should add resource file (.qrc) and paste your image to it. Use syntax loads pixmap from resource file.

2. Try paste dividers how home/tim/Pictures/HPIM0406.JPG or /home/tim/Pictures/HPIM0406.JPG or home\\tim\\Pictures\\HPIM0406.JPG. Some remark: you wrote ‘”/home/tim/Pictures/HPIM0406.JPG”‘, ” – use not single quotes into QPixmap constructor. I don’t understand, you wrote just in here or into your code.

I hope it helps you 🙂