Windows Forms C# application - Automatically handle DPI Scaling when a user sets the display to 125% or 150%

We had designed a Windows Form application such that it is suitable for all the resolutions. We came across a situation where the applications appear to be incorrectly sized when the user chooses 125% or 150% in the machine display setting . I have set the screen resolution to 1440x900 and changed the setting to 125% as shown in screenshot below

After making these settings to the machine and running the application, we found that the application appear to be incorrectly sized and the controls are getting overlapped with the other controls in the application

Can you please suggest any code/process for detecting the display settings i.e above 100% and handle the applications such that it appears correctly?

2 answers

Castorix31 81,836 Reputation points

2020-12-07T08:21:42.577+00:00

Did you see : High DPI support in Windows Forms ?
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Srinivas Kamalanathan Attipattu 1 Reputation point

2020-12-07T11:37:14.537+00:00

Yes.. I have checked that documentation link only and implemented it in our application. Even then some of the label text controls in the forms are getting overlapped with the other controls and some are coming out of the containers. If i set the DPI scaling back to 100 % then the application seems to look good. Is there any other changes that needs to be done in order to support different DPI scaling like 125% and 150%? Please suggest
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Daniel Zhang-MSFT 9,621 Reputation points

2020-12-08T05:22:11.79+00:00

Hi SrinivasKamalanathanAttipattu-9545,
First, you should change the AutoScaleMode of Form to the Dpi which Specifies the different types of automatic scaling modes supported by Windows Forms.
Then you can try to use dock and anchor properties to auto resize and adjust Form controls.
Here some related threads you can refer to.
Windows Forms DPI scaling
Creating a DPI-Aware Application
Automatic scaling in Windows Forms
Best Regards,
Daniel Zhang

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Srinivas Kamalanathan Attipattu 1 Reputation point

2020-12-08T05:52:20.363+00:00

Is there any possibility to check if the DPI scaling is > 100% during run time? If so, Can you please let me know the process of checking it ? i have tried the following code but every time it is returning 96 dpi even if i set high screen resolution 1440x900 and set the DPI scaling to 125%

float dx, dy;

Graphics g = this.CreateGraphics();
try
{
dx = g.DpiX;
dy = g.DpiY;
}
finally
{
g.Dispose();
}

Can you please suggest how to detect DPI scaling which is > 100%?

Daniel Zhang-MSFT 9,621 Reputation points

2020-12-08T09:29:03.867+00:00

Hi @Srinivas Kamalanathan Attipattu ,
First, I made a test with you code. I get a correct return value 120 pixels when I set high screen resolution 1440x900 and set the DPI scaling to 125%.
And If my form is first loaded in a non 96 DPI screen, I will get the same value 96 pixels even if I set another DPI.
So does your form first load in a non 96 DPI screen?
If so, I suggest you create your form in default setting at the first time.
As follows:

Best Regards,
Daniel Zhang

Castorix31 81,836 Reputation points

2020-12-08T09:32:41.647+00:00

With DPI APIs like GetDpiForWindow

You need a Manifest to get correct results with :

<application xmlns="urn:schemas-microsoft-com:asm.v3"> <windowsSettings> <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/PM</dpiAware> <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitor</dpiAwareness> </windowsSettings> </application>

I get :
96 for 100%
120 for 125%
144 for 150%
etc...

Srinivas Kamalanathan Attipattu 1 Reputation point

2020-12-08T10:35:17.297+00:00

Thank you very much for this suggestion. After adding the manifest file to the application , i am able to get the correct DPI scaling for 100%, 125% and 150%. to the code which i have sent earlier

I have used the following line of code in order to get the exact DPI scaling at run time.

Registry.GetValue("HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\ThemeManager", "LastLoadedDPI", "96")

Is this the correct way of retrieving DPI scaling value at run time? And also can you please suggest how can i scale the controls based on this DPI value?

Srinivas Kamalanathan Attipattu 1 Reputation point

2020-12-08T10:48:58.423+00:00

I tried loading the form first in a non 96 DPI screen and then loading it in a 96 DPI screen and vice versa. In both cases the DPI scaling is 96 only..

We have designed our application in the default setting 100% 96 DPI at the first time.. I have tried the solution provided below by Castorix and now i am able to get the exact DPI scaling.

Can you please suggest how can i scale the controls based on this DPI value?

Daniel Zhang-MSFT 9,621 Reputation points

2020-12-09T05:53:16.607+00:00

Hi @Srinivas Kamalanathan Attipattu ,
The ContainerControl has a AutoScaleMode property which sets the automatic scaling mode of the control, such as ToolStripContainer,ToolStripPanel.
And not all controls properly scale themselves, so in order to handle that you'll have to manually perform additional scaling as required.
Ian Boyd has provided a code example to scale the listview in this thead you can refer to.
And there are some controls that do not support correct scaling listed in this thread.
Best Regards,
Daniel Zhang
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