qt 获取dpi,在Qt中获取物理屏幕尺寸

àì夳堔傛蜴生んèń 2022-08-30 11:14 314阅读 0赞

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I'km working in Qt, i need help to get the physical size of the screen (monitor),

In Qt one can get a QDesktopWidget from QApplication, I mean:

QDesktopWidget \*mydesk = QApplication::desktop();

The QDesktopwidget has some methods to get the resolution in pixels and some to get the the size in milimethers:

mydesk-> widthMM(); mydesk->heightMM();

However, this does not correspond to the physical size, when I measure my screen with a ruler, there is a considerable difference.

Also one can get the DPI measurement and calculate the size of the screen:

mydesk->physicalDpiX(); mydesk->physicalDpiY();

double Winches = (double)mydesk.width() / (double)mydesk.physicalDpiX();

double Hinches = (double)mydesk.Height() / (double)mydesk.physicalDpiY();

where mydesk.width() and mydesk.height() give the size in pixels(resolution)

However the measurement is also wrong and very close to mydesk.widthMM() and mydesk.heightMM()

Also I have triyed mydesk.logicalDpiX() and it has similar results.

解决方案

Here is my (quick and dirty) example. It seems to work for me and I hope it works for you. I'm assuming you can take care of main.cpp on your own. I did this on a MacBook Air 11.6" and substituted a picture of a dime for the USA icon included with OS X:

\#ifndef WINDOW\_H

\#define WINDOW\_H

\#include

class Window : public QWidget

Q\_OBJECT

public:

QWidget \*canvas;

QSlider \*slider;

QPixmap pixmap;

private:

qreal zoom;

qreal pixels;