Retina QPixmap

kegon

I am trying to support Retina displays for my applications via Qt 5.0.1 / MacOS X 10.8.3.

Under Retina simulation, my application window and all widgets are drawn in High DPI but the pixmaps are pixellated and blocky.

My interpretation of what I have read is that I can do this

@
QIcon about_icon(QPixmap(":/info.png"));
about_icon.addPixmap(QPixmap(":/info@2x.png"));

QToolButton about_button = new QToolButton;
about_button->setIcon(about_icon);
@

I tried adding

@qputenv("QT_HIGHDPI_AWARE", "1");@

to my main widget constructor and also changing to

@
QIcon about_icon(QPixmap(":/info.png"));
QPixmap about2x(":/info@2x.png");
about2x.setDevicePixelRatio(2.0);
about_icon.addPixmap(about2x);

QToolButton about_button = new QToolButton;
about_button->setIcon(about_icon);
@

but neither approach helps.

My understanding was that a QPixmap loading a filename of the type "foobar@2x.ext" would automatically tag it as High DPI; but something is still missing here.

kegon

Simulating Retina on my laptop was doing my head in, so I now use a mini DisplayPort-HDMI cable connected to a 1920x1080 external monitor.

When I move windows to the second display, Qt does not promote them; only system window decorations get promoted to HighDPI.

kegon

qApp->devicePixelRatio() reports a value of 2 under simulation.

If I create a QIcon with a single 2x pixmap, with setDevicePixelRatio(2), I still get pixellated icons -

@
QIcon about_icon;
QPixmap about2x(":/info@2x.png");
about2x.setDevicePixelRatio(2);
about_icon.addPixmap(about2x);
@

kegon

I found this document in source https://qt.gitorious.org/qt/qtbase/blobs/da6bdffdcdb57669af13cfd531151fe0abc05be3/src/gui/doc/src/highdpi.qdoc

but I can't see where this comes from or what versions it affects.

Trying export QT_EMULATED_HIGHDPI=1 has no effect.