How to set monitor scaling to recommended or desired scaling with c++ ?

Question

How to set monitor scaling to recommended or desired scaling with c++ ?

Jaka Kostanjevec 0

I am trying to set scaling to windows recommended scaling or to desired one (100%,150%,...) for monitor in C++. I have monitor handles (type: HMONITOR). Is that enough or do I need anything else how would I set scaling from code.

Jeanine Zhang-MSFT 11,341 Reputation points Microsoft External Staff

2023-08-25T06:40:45.73+00:00

If you want to change display scaling Programmatically, I suggest you could refer to the thread: https://stackoverflow.com/questions/35233182/how-can-i-change-windows-10-display-scaling-programmatically-using-c-sharp
Jeanine Zhang-MSFT 11,341 Reputation points Microsoft External Staff

2023-09-01T08:39:21.1666667+00:00

Have you got any updates about this issue? Could you please check my suggestion?
jaka kostanjevec 0 Reputation points

2023-09-01T09:14:37.37+00:00

Thank you. Your suggestion worked. I used what i needed but it was the only thing that actually worked with setting each monitor scaling to desired value.
Apoorve Singhal 0 Reputation points

2025-04-17T20:39:06.86+00:00

Hi @jaka kostanjevec , how did you get the recommended scaling? It would be very helpful!!

1 answer

Your answer

Jeanine Zhang-MSFT 11,341 Reputation points Microsoft External Staff

2023-08-25T06:40:45.73+00:00

If you want to change display scaling Programmatically, I suggest you could refer to the thread: https://stackoverflow.com/questions/35233182/how-can-i-change-windows-10-display-scaling-programmatically-using-c-sharp
Jeanine Zhang-MSFT 11,341 Reputation points Microsoft External Staff

2023-09-01T08:39:21.1666667+00:00

Have you got any updates about this issue? Could you please check my suggestion?
jaka kostanjevec 0 Reputation points

2023-09-01T09:14:37.37+00:00

Thank you. Your suggestion worked. I used what i needed but it was the only thing that actually worked with setting each monitor scaling to desired value.
Apoorve Singhal 0 Reputation points

2025-04-17T20:39:06.86+00:00

Hi @jaka kostanjevec , how did you get the recommended scaling? It would be very helpful!!

Answer 1

Castorix31 88,541

You can change scaling with SystemParametersInfo and SPI_SETLOGICALDPIOVERRIDE

Jaka Kostanjevec 0

I have following function but if I put scalingPercentage to 100 it sets scaling to 125% any idea why ?

And is there a way to set specific monitor to specific scaling and not just set all of them to the same scaling ?


bool Monitors::SetScalingForMonitor(HMONITOR hMonitor, int scalingPercentage) {
	if (scalingPercentage < 1 || scalingPercentage > 500) {
		// Ensure scalingPercentage is within a reasonable range (1% to 500%)
		return false;
	}

	// Calculate DPI based on the scaling percentage (standard DPI is 96 for 100%)
	UINT dpi = static_cast<UINT>(96 * scalingPercentage / 100);

	DEVMODE dm;
	ZeroMemory(&dm, sizeof(dm));
	dm.dmSize = sizeof(dm);
	dm.dmFields = DM_LOGPIXELS;
	dm.dmLogPixels = dpi;

	if (ChangeDisplaySettingsEx(NULL, &dm, NULL, CDS_UPDATEREGISTRY, NULL) == DISP_CHANGE_SUCCESSFUL) {
		// Notify the system of the change
		if (SystemParametersInfo(SPI_SETLOGICALDPIOVERRIDE, TRUE, NULL, SPIF_SENDCHANGE | SPIF_UPDATEINIFILE) != 0) {
			return true;
		}
	}

	return false; // Failed to set scaling
}

Castorix31 88,541 Reputation points

2023-08-24T13:01:10.49+00:00

uiParam of SystemParametersInfo is not a boolean, it is an index (0, 1, 2, ...)
Jaka Kostanjevec 0 Reputation points

2023-08-24T13:30:56.5833333+00:00

Ok but how do I specify on which monitor scaling should be changed then (I have multiple and I want to set different scaling on them) ?
Castorix31 88,541 Reputation points

2023-08-24T13:47:50.7833333+00:00

I have only 1 monitor, so I cannot do tests

But other people tried and you can test samples like https://github.com/lihas/windows-DPI-scaling-sample

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How to set monitor scaling to recommended or desired scaling with c++ ?

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