Looks good to me, and very much in line with the other canConvert statements before.

I propose to also extend the KAboutData::programLogo documentation to specify that QIcon is supported/expected. So this is not some surprise bebaviour.

While at it, please also note there recommended logo pixmap size usages, to avoid blurring.

Would something like this be ok?

Not sure what to write about sizes, e.g. for the program icon we don't mention anything either.

The QPixmap case was missing in the docs, too, btw.

diff --git a/src/lib/kaboutdata.h b/src/lib/kaboutdata.h
index 7b317f7..c9f8da0 100644
--- a/src/lib/kaboutdata.h
+++ b/src/lib/kaboutdata.h
@@ -750,8 +750,10 @@ public:
      * Use this if you need to have an application logo
      * in AboutData other than the application icon.
      *
-     * Because KAboutData is a core class it cannot use QImage directly,
-     * so this is a QVariant that should contain a QImage.
+     * Because KAboutData is a core class it cannot use QImage/QPixmap/QIcon directly,
+     * so this is a QVariant that should contain a QImage/QPixmap/QIcon.
+     *
+     * QIcon should be preferred, to be able to properly handle HiDPI scaling.
      *
      * @param image logo image.
      * @see programLogo()
@@ -964,8 +966,8 @@ public:
     /**
      * Returns the program logo image.
      *
-     * Because KAboutData is a core class it cannot use QImage directly,
-     * so this is a QVariant containing a QImage.
+     * Because KAboutData is a core class it cannot use QImage/QPixmap/QIcon directly,
+     * so this is a QVariant containing a QImage/QPixmap/QIcon.
      *
      * @return the program logo data, or a null image if there is
      *         no custom application logo defined.

In D26903#600771, @cullmann wrote:

Would something like this be ok?

Not sure what to write about sizes, e.g. for the program icon we don't mention anything either.

The program icon I have and such would assume others as well to be thought to have to satisfy the usual icon sizes (as defined for application cons in the xdg spec), given it is named "icon" after all.

For the programLogo things are different, logo display sizes are not specified somewhere (unless one indirectly assumes them given that the application icon is named as default). So possibly best would be to hint that any pixmaps passed here (via direct or also via QIcon) should follow the xdg icon spec, so have some 48x48 icon (or multiple of).

The QPixmap case was missing in the docs, too, btw.

Good catch :)