Windows 10 - Different dpi text size settings per screen - How to detect?

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There seems to be two ways of changing the text size in Windows 10:

1. "set a custom scaling level" - which allows you to set the system to 96-dpi, 120-dpi, etc. My application detects this fine. My 1920x1080 screen is detected as 1920x1080 fine.

2. On a screen by screen basis by with the "Change the size of text, apps, and other items" option per screen. My application doesn't detect this and my 1920x1080 screen shows up in my program as 1536x864 pixels.

First thing I need to do is detect number 2 above and adjust the number of pixels collected from:

Dim Screens() as Screen = Screen.AllScreens

which is showing 1536x864 pixels.

I am using Framework 4 (I still have clients using Windows XP, so can't move).

Any help would be appreciated. Thanks.

Posted 17-Nov-15 2:22am

Wedgwood

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Sergey Alexandrovich Kryukov 17-Nov-15 10:17am

Making text size depending on screen size looks like utterly bad approach in almost all cases. Application usually has resizable window and floating layout, so the context is shown nicely in any size between MinimumSize and screen...
—SA

Wedgwood 18-Nov-15 5:50am

Just to clarify, the application scales fine. It's the detection of the correct screen resolution when Windows 10 is using the "Change the size of text, apps, and other items" option per screen that is the issue. Thanks.

Sergey Alexandrovich Kryukov 18-Nov-15 12:28pm

All right, great. Then I would like to understand why you want to "detect" it. Is the problem is capturing the event of changing this system-wide property during application runtime? Anything else?

(By the way, "resolution", despite the wide use, by Microsoft (notoriously messing up terminology, sometimes to real serious confusion, like in case of "Unicode") and others, is a wrong term. This is just a size of screen in pixels. Resolution is related to the characteristic of system to resolve lines/points, measured in dots per mm/inch.)

—SA

Wedgwood 19-Nov-15 4:43am

Windows Display in the Control Panel is showing the screen as having 1920x1080 pixels. At a text size of 100%, then using the .NET:

Dim Screens() as Screen = Screen.AllScreens

On a single screen system, with custom scaling set to either 96 or 120 dpi, Screens(0).Bounds.Width equals 1920 and Screens(0).Bounds.Height equals 1080.

Now heres the problem. With Windows 10, if the user uses the Change the size of text, apps, and other items" option per screen, then the screens code returns different values. I.e. Screens(0).Bounds.Width equals 1536 and Screens(0).Bounds.Height equals 864 instead.

I guess I need an alternative way of collecting the screen information.

Sergey Alexandrovich Kryukov 19-Nov-15 11:53am

Thank you for answering. Now, did I understand it right? Is the only issue when the user changes screen settings during your application runtime, or do you detect the screen size in the very beginning? Do you scale (not just resize) the application depending on that? You may think that what you are trying to do is obvious, but it's not. Most application don't try to maintain certain size of aspect ratio at all. You maximize window, and it takes appropriate size, the user resizes it, and it takes new size without any scaling; and still everything is shown fine, despite extremely low sizes, which can be limited. Essentially, from the very beginning, I was trying to ask what's wrong with this simple model, and what makes you designing something more complicated? Yes, I'm aware of different layout/scaling style where everything is measured in relative screen units. The goal is to maintain physical sized (in mm, not in pixels) for all elements on different hardware. Is that what you want to achieve? Something else?
—SA

Wedgwood 19-Nov-15 5:17am

Just found that Windows 8 does the same. It has two different text sizing options:

1. "Change the size of all the items" - which is standard dpi stuff and using the Screens() function gives the correct screen resolution.

2. "Let me choose one scaling level for all my displays". When reports the wrong screen resolution the same as for Windows 10.

Sergey Alexandrovich Kryukov 19-Nov-15 12:00pm

Well, please see my previous comment. Essentially, I was trying to ask: what makes you preferring the approach #2?
Actually, I would question even approach #1 and ask why not using the standard way not resizing anything, but I can understand where you come from. Please understand: both scaling the whole UI (not part of it such as graphics, but the whole look), and maintaining the same physical size on all displays are not dominant approaches, so using them is not so obvious as you may think; and that's why I'm asking. Could the solution would be to redesign things in order to get away from these complications? Just a suggestion...
—SA

Wedgwood 20-Nov-15 7:21am

In a nutshell, does anyone now how to collect the correct physical number of pixels from a screen, regardless of the text sizing? The .NET code:

Dim Screens() as Screen = Screen.AllScreens

doesn't always return the correct values. Thank you.

Sergey Alexandrovich Kryukov 21-Nov-15 0:11am

Yes, your formulation of the problem is clear...
—SA

elte 3-Mar-16 10:14am

Having the same problem here. In Windows 10, the user can adjust the slider for "Change the size of text, apps, and other items". I need to be able to detect that value: 100%, 125%, 150%, etc...

AndrewInEssex 2-Jun-18 5:08am

Hi, did you ever find out how to do this? I have a problem with pointtoscreen returning the wrong values if the size is set to other than 100%.

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Windows 10 - Different dpi text size settings per screen - How to detect?

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