QLabel and image antialiasing

v8671

Hello , excuse me if this forum is not pertinent to my question but i do not know where to post, i am using a qlabel to draw an image and actually i do not want it to be antialised when zoomed in, how can i achieve this ?
thanks

mrjj

Hi and welcome to the forums
It is a perfectly fine place to ask :)

QLabel uses Qt::SmoothTransformation and there seems not to be a way to disable it
https://code.woboq.org/qt5/qtbase/src/widgets/widgets/qlabel.cpp.html

But you can easily make a custom widget with paintEvent and draw the image
yourself not using smoothing.

v8671

@mrjj Holy cow, how can i draw a raw bitmap pixel by pixel ????

VRonin

@v8671 said in QLabel and image antialiasing:

Holy cow, how can i draw a raw bitmap pixel by pixel ????

That's not what was suggested.

@mrjj was talking of something like:

class NonAntiAliasImage : public QWidget{
    Q_OBJECT
    Q_DISABLE_COPY(NonAntiAliasImage)
public:
    explicit NonAntiAliasImage(QWidget* parent = Q_NULLPTR) 
        : QWidget(parent)
    {}
    const QPixmap& pixmap() const 
    {
        return m_pixmap;
    }
    void setPixmap(const QPixmap& px) 
    {
        m_pixmap = px;
        update();
    }
protected:
    void paintEvent(QPaintEvent*)
    {
        QPainter painter(this);
        painter.setRenderHint(QPainter::Antialiasing, false);
        style()->drawItemPixmap(&painter, rect(), Qt::AlignCenter, m_pixmap.scaled(rect().size()));
    }
private:
    QPixmap m_pixmap;
};

v8671

Thanks Vronin , that worked flawlessly