Opacity of a QImage becomes black

timain

Hello,

I want to set opacity of my image, when I save it (PNG or JPEG), transparent image becomes black/dark image
Someone could help me? ( I used ARGB32 format )

Thank you.

Bondrusiek

I have the same problem. Code without set opacity

            QImage image = m_GemsPixmap.copy(p.kind*49, 0, 49, 49).toImage().convertToFormat(QImage::Format_ARGB32);
            //            for (int x(0); x != image.width(); ++x)
            //            {
            //              for (int y(0); y != image.height(); ++y)
            //              {
            //                QColor color(image.pixel(x,y));
            //                color.setAlpha(p.alpha);
            //                image.setPixel(x, y, color.rgba());
            //              }
            //            }
            m_pixmapItems[i][j].setPixmap(QPixmap::fromImage(image));

Result

Code with control opacicty.

            QImage image = m_GemsPixmap.copy(p.kind*49, 0, 49, 49).toImage().convertToFormat(QImage::Format_ARGB32);
            for (int x(0); x != image.width(); ++x)
            {
                for (int y(0); y != image.height(); ++y)
                {
                    QColor color(image.pixel(x,y));
                    color.setAlpha(p.alpha);
                    image.setPixel(x, y, color.rgba());
                }
            }
            m_pixmapItems[i][j].setPixmap(QPixmap::fromImage(image));

Result:

Transparent area is always black but for other opacity work correctly.
Do you know how solve that?

SGaist

Hi,

Do you mean that you need alpha to be at least 1 in order to have proper transparency handling ?