Why is Screen returning a lower resolution than my Windows 8 tablet is set to?

Question

I've got a Windows 8 tablet with a Full HD resolution of 1920x1080 pixel set.

But when I use Delphi's Screen object to get the Screen.Width and Screen.Height it will return a resolution of 1280x720 running on that Windows 8 tablet.

Where is the problem rooted? On the Windows (tablet) side or on the Delphi side? I use Delphi 7 up to XE2 with equal results. This seems to be rather a tablet problem than a general Windows 8 problem since I do not have such a behavior on my Windows 8.1 desktop machine.

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Conclusion

I just wanted to highlight the cause of my problem since it is kind of hidden in the comments.
By default Windows 8 on my tablet is using 150% DPI. 1080px are 150% of 720px. So 720px are usable by applications. Decreasing the DPI percentage to 100% results in the expected 1080px resolution.

Answer 1

It could be DPI-related problem. Aero can handle high-DPI situations in two ways:

• Say to the application, that DPI is greater than standart 96, and let it scale itself
• Lie to the application, that DPI is usual 96, and scale it's window with some image-scalling algorithm (produces blur)

May be in the second situation Aero is lying not only about DPI, but also about screen resolution.

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If the second scenario is your case, then DO NOT turn off scaling. Just make your application DPI-aware: http://www.rw-designer.com/DPI-aware - general info http://www.micro-isv.asia/2010/09/high-dpi-support-in-windows-vista-and-7/ - delphi

Answer 2

Definition on Full HD is debatable.

Industry has adopted the term Full HD as the consumer-friendly marketing term to mean the device is a safe purchase because it can display at least one of the available HD resolutions.

Your device supports an aspect ratio of 16:9 which is the international standard for HD.

The two most publicly known full HD resolutions are :

• 1280 x 720 (720p)
• 1920 x 1080 (1080p)

The fact that your device says that it is full HD simply means that the display of the device at a minimum supports a resolution of 720p, up to 1080p.

Given that this is a tablet it should become apparent that it's native resolution is 720p HD. The fact that you can force 1080p just means exactly that, a display marked as Full HD which is able to display 1080p. Does not mean 1080p is it's native resolution.

To answer your question, Delphi neither Windows is at fault.