QScreen physicalDotsPerInch unreliable on Android

QScreen physicalDotsPerInch is unreliable on Android.
I deployed an application onto a Nexus 10 and a Nexus 4, both which have similar pixel densities (300 and 320, respectively). The values I get for the Nexus 4 are totally inaccurate.

I used an Android app [1] which gives me the values Android knows of and created a test QML app and tried it on various devices (Nexus 4, Nexus 7 2012 and Nexus 10). Here is the results:

Let screen be qApp->primaryScreen()

My Desktop Computer (20" 1680x1050)
screen->physicalDotsPerInch() = 98.66371567872721 (correct!)
screen->physicalDotsPerInchX() = 98.54965357967667
screen->physicalDotsPerInchY() = 98.77777777777777
screen->physicalSize().width() = 433
screen->physicalSize().height() = 270
screen->geometry().width() = 1680
screen->geometry().height() = 1050

Nexus 4 (4,7" 1280x768)
This device as onscreen navigational keys which take around 100px of vertical space which is not available to the application
DPI Screen Info App:
Screen width: 768
Screen height: 1184
Screen density: 2.0
Screen density DPI: 320 (DENSITY_XHIGH)
screen->physicalDotsPerInch() = 163.48531876138432 (wrong!)
screen->physicalDotsPerInchX() = 159.89508196721312
screen->physicalDotsPerInchY() = 167.07555555555555
screen->physicalSize().width() = 122 (I measured about 62mm)
screen->physicalSize().height() = 180 (I measured about 90mm with system chrome, 105mm for the entire screen)
screen->geometry().width() = 768
screen->geometry().height() = 1184

As you can see here, the physical size of the device is exactly 50% of what it should be, which results in the wrong (halved) DPI.

Nexus 10 (10,055" 2560x1600)
DPI Screen Info App:
Screen width: 2560
Screen height: 1504
Screen density: 2.0
Screen density DPI: 320 (DENSITY_XHIGH)
screen->physicalDotsPerInch() = 298.055355661438296 (correct!)
screen->physicalDotsPerInchX() = 298.27522935779814
screen->physicalDotsPerInchY() = 297.8354838709677
screen->physicalSize().width() = 218 (I measured about 215mm)
screen->physicalSize().height() = 124 (I measured about 125mm with system chrome, 137mm for the entire screen)
screen->geometry().width() = 2560
screen->geometry().height() = 1454

As you can see, the values reported for the Nexus 10 are really accurate.

Nexus 7 (7" 1280x800)
DPI Screen Info App:
Screen width: 2560
Screen height: 1504
Screen density: 2.0
Screen density DPI: 320 (DENSITY_XHIGH)
screen->physicalDotsPerInch() = 198.26257796257798 (correct!)
screen->physicalDotsPerInchX() = 195.3846153846154
screen->physicalDotsPerInchY() = 201.14054054054054
screen->physicalSize().width() = 104 (I measured about 93mm)
screen->physicalSize().height() = 148 (I measured about 137mm with system chrome, 150mm for the entire screen)
screen->geometry().width() = 800
screen->geometry().height() = 1172

[1] https://play.google.com/store/apps/details?id=com.tspmobile.dpiscreeninfo