Manipulate scaling percentage per resolution

I often find myself wishing I could have Windows select a specific scaling factor based on resolution. When setting desktop resolution to 2560×1440 to play games sitting at my desk I prefer 100% but when I am connected via my Steam Deck at 2560x1600, I prefer 175% and 4k connected via my 55” TV, 200%.

Could you please add some mechanism for defining a resolution to scaling factor relationship?

Unfortunately there isn’t a Windows API call I am aware about that allows adjusting the monitor DPI setting. The only one I’ve found was essentially a reverse engineered call. If you happen to know the proper API calls for it I can implement it, otherwise I’d suggest getting a dummy plug and having the dummy plug set at 200%

That is a bummer. The request was so I could manipulate the scaling factor of my dummy plug. When I mentioned being at my desktop I am streaming to my Mac. My Windows PC is a headless dedicated streaming machine. I’ll keep my eye out for a proper API

There is a fork that seems to adjust scaling: main...danielmartina:ResolutionAutomation-custom:main.

The parameter utilized, 0x009F is documented by Microsoft as “do not use”

https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-systemparametersinfoa

Also getting the vibe this is steps above recommended, which would mean I’d need a negative number at 1440p and that isn’t possible

I tried that API call earlier and it completely broke my DPI scale dropdown. I couldn't pick a setting anymore and was forced to use custom scaling. Had to do a system restore to fix it again

I was poking around at this again this morning and thought maybe looking for an API which applies a scaling factor is incorrect.

If you run something like this...you get the virtual resolution of the desktop after the chosen scaling factor has been applied.

[System.Windows.Forms.Screen]::AllScreens

I wonder though if when you select the factor through Display Settings it isn't actually setting a percentage anywhere, it is just taking the desired frame buffer resolution, applying a reverse percentage (so 4k becomes 1920x1080 at 200%), then setting the virtual desktop size to that resolution. I saw a similar thing when working with Special-K, if it was made DPI aware it would report my resolution as a fraction of what I had set the actual display resolution to.

Looking more through what's available from user32.dll though, I couldn't find anything which obviously provided a way to set that virtual desktop resolution. I am new to Windows API stuff so maybe I am not seeing it or not looking in the right place...

I have the same need, looking forward to the update.

I have a workaround for now. Using this executable, drop SetDPI.exe in the ResolutionAutomation folder and modify Events.ps1.

At the end of the OnStreamStart function I have:

if ($env:SUNSHINE_CLIENT_HEIGHT -gt 1079) {
    .\SetDPI.exe 125
}

At the end of the OnStreamEnd function I have:

.\SetDPI.exe 100

So that anything 1080p or higher will get a 125% scaling. You can adjust this to your liking.

EDIT 1: Fixed code error
EDIT 2: Updated for v3.1

I have a workaround for now. Using this executable, drop SetDPI.exe in the ResolutionAutomation folder and modify Events.ps1.

At the end of the OnStreamStart function I have:
if ($env:SUNSHINE_CLIENT_HEIGHT -gt 1079) {
    .\SetDPI.exe 125
}
At the end of the OnStreamEnd function I have:
.\SetDPI.exe 100
So that anything 1080p or higher will get a 125% scaling. You can adjust this to your liking.

EDIT 1: Fixed code error EDIT 2: Updated for v3.1

Just what I need this but I can't seem to get this to work for 3.1.2.

In the OnStreamStart should the bottom look like this?

    Set-ScreenResolution -Width $expectedRes.Width -Height $expectedRes.Height -Freq $expectedRes.Refresh
    Assert-ResolutionChange -width $expectedRes.Width -height $expectedRes.Height -refresh $expectedRes.Refresh

if ($env:SUNSHINE_CLIENT_HEIGHT -gt 1079) {
    .\SetDPI.exe 125
}

Same for the OnStreamEnd

Is that just

    Set-ScreenResolution -Width $originalResolution.Width -Height $originalResolution.Height -Freq $originalResolution.Refresh   
    Write-Debug "Screen resolution set to: $($originalResolution.Width) x $($originalResolution.Height) x $($originalResolution.Refresh)"

    return $true
}

.\SetDPI.exe 100

So there is no curly brace after?

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Manipulate scaling percentage per resolution #69

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