CODEWITHSUNDEEP
winapiwindows-8.1resolution
Noitidart
Noitidart

Reputation: 37228

In Win81+ non-dpi aware process, figure out scale factor

I'm having an issue in that I am coding for a non-dpi aware process, until a bug fix lands.

So for now I need to do a work around. My thought is this: figure out the scale up factor, and give my elements width/height scaled down by that much.

So right now I am drawing a canvas that is full width and height of second monitor, it s 1920 x 1080 (WxH). But visuaully (as measured by photoshop after screenshot) it is coming out to be 2880 x 1620. This is a scale up factor of 1.5 (2880 divided by 1920 or 1620 divided by 1080).

I tried getting dpi with methods of GetDeviceCaps and EnumDisplaysettings but all of them returned that of the primary monitor (note: EnumDisplaySettings sets dmLogPixels which I think is DPI to 0 if I do EnumDisplaySettings with constnat of ENUM_REGISTRY_SETTINGS so I had to use ENUM_CURRENT_SETTINGS).

The only method i found that returns differently is GetDpiForMonitor with MONITOR_DPI_TYPE constnat of MDT_Angular_DPI or MDT_Raw_DPI, if I use MDT_Effective_DPI it gives that of the primary monitor.

So now this is my results of running GetDpiForMonitor:

None of the secondary values divided by the primary are giving me a scale up factor 1.5. Is there anyway to get this scale factor?

Thanks

Upvotes: 0

Views: 509

Answers (1)

Noitidart
Noitidart

Reputation: 37228

I just had an idea nad it works I am getting the scaled height/width with any of the three methods outlined in my question here: Improper width and height for second monitor from GetMonitorInfo and GetDeviceCaps

  • GetDeviceCaps on hdcScreen or
  • GetMonitorInfo or
  • EnumDisplayMonitors

Then I divide it by the width/height from EnumDisplaySettings.

This is the only way I found how, is there any other way? Can the experts please verify.

Upvotes: 1

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