[Interest] DPI

[igor.mironchik at gmail.com]

I’m absolutely sure that Qt determines DPI wrong.

I’ve received from Qt that my screen has 72 DpiY, where actually it has 130.

So my question is what can I use else then QDesktopIWidget::physicalDpiY()?

I need cross-platform solution of finding average finger size (it’s somewhere 10 mm)...

From: Andre Somers 
Sent: Sunday, February 23, 2014 1:30 PM
To: interest at qt-project.org 
Subject: Re: [Interest] DPI

igor.mironchik at gmail.com schreef op 23-2-2014 13:24:

  Hi.

  I want to determine how much pixels in 10 mm.

  I use the next calculations:

  static const qreal fingerSize = 0.0393700787 * 10;

  static const qreal h = (qreal) QApplication::desktop()->physicalDpiY() * fingerSize; 

  And this calculations return to me 28 that on my desktop is 5 mm only.

  0.0393700787 is how  much inches in millimeter...

  What am I doing wrong?

Are you sure that the right physicalDpi is returned? That is not a value you can absolutely rely on.

André




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