2018 and still no solution for 90° rotated text labels with antialiasing?

[UrbanCee]

Is there still no easy way of rotating a QLabel containing text? I can use QPixmap, sure, but what about antialiasing? I know this has been asked before but that was during Qt 4.x, maybe in 5.10 there should be something convenient!

[Pablo J. Rogina]

@UrbanCee do you know how this could be solved? Is there any code you can contribute to the Qt Project?

[JKSH]

@UrbanCee Will a QPainter do? https://stackoverflow.com/questions/17820428/how-to-rotate-text-for-drawtext

[UrbanCee]

So you mean subclassing QLabel and change Painter in there? Or is it possible to change the painter from a Widget from the outside?

[JKSH]

@UrbanCee said in 2018 and still no solution for 90° rotated text labels with antialiasing?:

So you mean subclassing QLabel and change Painter in there? Or is it possible to change the painter from a Widget from the outside?

Using QPainter involves subclassing a widget and reimplementing paintEvent().

Note: I haven't tried this myself; this is just an idea. This approach will involve calculating the the coordinates and size of the text to be painted, using values of various QLabel properties.

[UrbanCee]

I C. I wanted to avoid that. Thought there would be an easier way.

[kshegunov]

In the development mailing list propose adding a transformation property that is applied automatically to the painter for the widgets when they paint their contents, see what people think and submit a suggestion/patch to the framework would be the way such a thing gets included. A user forum is the wrong place to request features.

[JKSH]

@UrbanCee said in 2018 and still no solution for 90° rotated text labels with antialiasing?:

Thought there would be an easier way.

Not with QLabels, unfortunately. As @kshegunov said, make a feature request if you feel strongly about it.

You mentioned that the QPixmap workaround has antialiasing issues. A possible alternative is to use an SVG file with a QSvgWidget instead of QPixmap.

[Devopia53]

@UrbanCee

If the size of the QLabel is square and it only rotates 90/180/270 degrees, it can be simplified as follows.
Otherwise, as @JKSH said, you must calculate and process the changed size after rotation of the QLabel.

like this:

void MyLabel::initPainter(QPainter *painter) const
{
    painter->translate(rect().center());
    painter->rotate(90);
    painter->translate(-rect().center());
}