how to get screen pixel size?

[kodiak]

Hi,

Does anyone know how to get pixel size with Qt?

Thanks

[wysota]

Do you mean the resolution? Take a look at QDesktopWidget and what it offers.

[kodiak]

wysota, I just need a pixel or screen width and height in millimeters. I have to draw symbols at the same dimension on defferent screens and resolutions.

[pherthyl]

wysota, I just need a pixel or screen width and height in millimeters. I have to draw symbols at the same dimension on defferent screens and resolutions.


All you can do is use the DPI that the system gives you to convert to a physical unit and then draw based on that. However, that DPI is not correct on most monitors, so drawing something to exactly the same physical size is practically impossible.

[wysota]

The pixel size is in its nature resolution independent (as opposed to point size, or vice versa - in that case revert everything I say here), so if you count everything in logical pixels (and not points) you should get consistent sizes (this especially applies to fonts).

[kodiak]

There is solution in QPaintDevice class. Methods widthMM() and heightMM() returns what I have been looking for!

[pherthyl]

There is solution in QPaintDevice class. Methods widthMM() and heightMM() returns what I have been looking for!

Yes, they return a measurement in millimeters, but you can't actually trust the value that it gives you. Sure it'll be sort of correct, but if you verify it with a ruler it won't match up (unless your monitor has a perfect DPI setting, which is very unlikely, and most people don't).