Never mind, this question is a duplicate. I might be able to figure this out from other sources.
I'm so so confused. I was working on my project and realised that the window created with CreateWindowEx() was bigger than I was specifying. I noticed the windows are bigger in release mode than in debug mode. Then I took the values of GetSystemMetrics(SM_CXSCREEN) and SM_CXFULLSCREEN and noticed that in debug mode it gives me 1920 x 1080, which is correct, but in release mode it gives me 1536 x 864.
Furthermore, if I just start a new Win32 project, which is up and ready to run just by pushing ctrl + F5, I get the wrong value in both debug AND release mode, same values as before, and the windows are bigger.
I don't see how providing any code might help, I could make a video of it, but... this just doesn't make sense. Could anyone maybe see if it happens to them by starting a new Win32 project, and seeing 1600 x 900 actually takes up that much space? Because 1600 x 900 takes up my entire screen when it shouldn't.
Thanks.
On further inspection, the 1536 x 864 resolution it gives me is 80% the size that it should be, or in other words it should be 1.25 times bigger, the reciprocal. Also if I change my desktop resolution to 1600 x 900 the metrics gives me 1280 x 720, which is again 80%, or the resolution is 1.25 bigger than what's given.
Well, this is a duplicate, but if this helps anyone I'll explain the problem of DPI scaling. Basically the default Windows setting is 96 DPI. There are options in Control Panel to "make stuff bigger", which is easier on the eyes. My slider is set to the middle one, which is equivalent to 125% bigger, or 120 dpi, which is why System Metrics was returning the wrong values, and my windows were bigger. The dpi gets bigger, so the system assumes it has to draw everything larger in proportion to the upscaling. If you consider someone programs a window to be 200 pixels across, when someone with a super duper double resolution display runs it, it's still going to be 200 pixels across, but half the physical size, say inch-wise. So by doubling the dpi "setting", not the dpi, but dpi "setting" from 96 to 194, or scaling it up 200% makes the window occupy 400 pixels across, but is the same size with respect to the original display.
Anyway, the easiest fix for this, if on Visual Studio, is simply through the project properties, go down to the "manifest" menu, then select "input/output", the last option should be DPI Awareness. Mine was on "None". It's only necessary in most cases to put it on "High DPI Aware", and that will fix the problem. The other option, which is "per monitor DPI awareness" means that it will adjust accordingly in a dynamic way, say for example the dpi scaling is changed while the app is running, or moving the window onto another monitor while it's running. The High DPI Aware setting will do a check at startup.
Interestingly, if you go to the properties of any exe, and under the compatibility tab, you can check "Disable display scaling on high DPI settings", and that will work also. Finally, there is a free program, now owned by Microsoft, called process explorer, which is basically like task manager with extra features, and you can select the DPI Awareness column and see which programs are DPI aware. Yes, DPI Awareness is a thing, I feel so dumb. There are also many other ways to do it, like with function calls and merging manifests, but I have no idea about that, and am too tired to even breathe now.
Related
I'm trying to properly DPI scale an application in C++ and I'm having trouble getting this to work with the File Picker window created from calling OPENFILENAMEW from commdlg.h.
I'm using three monitors: two with 1.0 dpi and one with 2.5 dpi. For me, the file picker only opens with 1.0 DPI regardless of what window my application is in. So when I drag the file picker to the 2.5 dpi monitor, the window is so small is hard to read. I can only get it to scale with 2.5 dpi when I disconnect the other monitors. I looked at the documentation for OPENFILENAMEW and there is a flag to allow the dialogue to resize manually but that's about it.
It has to register the dpi at some point to scale but I just can't find it.
Does anyone know how to do this?
Enabling per monitor DPI awareness in Manifest settings didn't solve this completely but it did lead me to the answer I was looking for! So the issue that persisted was that once the file-picker window was created, it kept it's DPI scale from its original window even after moving it to a window with different DPI.
Apparently the options in Manifest don't support this and neither does the SetProcessDpiAwareness function in the shellscaling api, which can be used to set that Manifest setting programmatically.
However, the SetProcessDpiAwarenessContext from winuser.h has one more option that the others don't: DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2. This can only be used on windows machines with the Creators update (named Redstone 2) and you can check that to do DPI scaling right when you can, and wrong but as good as possible when you can't:
if (IsWindowsVersionOrGreater(HIBYTE(NTDDI_WIN10_RS2), LOBYTE(NTDDI_WIN10_RS2), 0)) {
SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
}
else {
SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE);
}
And this works!
What's the correct way to deal with DPI scaling in an OpenGL application when the application is DPI monitor aware. aka:
SetThreadDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2);
I'm finding different behaviour on different devices - probably driver related, but some machines need to setup the viewport like this:
glViewport(0, 0, prc->right, prc->bottom)
while others need something like this:
glViewport(0, 0, (int)(prc->right * 96 / dpi), (int)(prc->bottom * 96 / dpi));
(where prc is the client rect and dpi is the current DPI of the window).
I've put together a simple demo program that shows the problem. The problems happen after changing the system scaling, but before signing out/back in.
Problems include:
Rendering at the wrong scale (not sure which driver is wrong)
Vertical shifting by what looks like the difference in the title bar height before changing the scaling vs after changing the scaling. (on macbook pro/bootcamp)
I've tried tearing down and recreating the wgl context on WM_DPICHANGED but to no avail and not sure what else to try.
Update: I've updated the sample program repo to include screen shots of what I'm seeing and I've included the .exe for the test program.
See here: https://bitbucket.org/toptensoftware/minimalopengl/overview
Update 2 - found a GPU that works as expected Radeon RX460. Updated screen shots in repo to show what's expected.
Update 3 - I'm now fairly confident this is caused by issues with the NVidia and Intel drivers and have logged bugs with both. I guess WHQL compliance doesn't cover OpenGL drivers.
Still... it'd be nice to have proper documentation or example program from Microsoft on how OpenGL and the per-monitor DPI support is supposed to work.
Have the same problem on gtx 1050. I've noticed that this problem only appears with SetThreadDpiAwarenessContext function.
from msdn:
SetThreadDpiAwarenessContext function.
Set the DPI awareness for the current thread to the provided value.
It means that if driver creates one or more additional threads to render OpenGL, each thread will have different dpi awareness level.
So there are three solutions:
Use old SetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE) function from Windows 8.1 and call EnableNonClientDpiScaling(hWnd) in WM_NCCREATE message;
Use new SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2) from Creators Update;
Set dpi awareness level in application manifest (will be applied to whole application).
Both functions set awareness level for whole process.
The MFC application looks weird with 150% DPI settings on Windows 7.
When display settings on Windows 7 are changed to 150% following things happen:
Toolbar gets expanded a lot making menu items almost invisible.
In addition, a black gap get's introduced between the toolbar and application frame (as shown in new)
The app used to work fine a while ago (as shown in old). Many changes have been introduced to the app including integration of DevExpress.
But nothing particularly changed in DPI settings.
Need help in understanding why this change might have occurred. And how to get rid of this unwanted zoom effect / DPI effect.
I am making my app dpi-aware per monitor by setting <dpiAware>True/PM</dpiAware> in the manifest file. I can verify with process explorer that this is indeed working or by calling GetProcessDpiAwareness.
This is all working fine and I can scale anything in the client area fine in my code. However, my only problem is that if I drag my app from a system-dpi monitor to a non-system dpi monitor, the title bar and any system menu would either become too big or too small. This isn't the case for most built-in apps (e.g. calc, edge browser, etc..) so there must be away to scale it properly. Does anyone how the devs at MS did this?
The screenshot below should explain my problem better. Also notice, that the padding between the close, min, and max button is different when it's scaled (96dpi).
Sample app I'm attaching a very simple app that is per-monitor dpi aware.
The Windows 10 Anniversary Update (v1607) has added a new API you must call to enable DPI scaling of the non-client areas: EnableNonClientDpiScaling. This function should be called, when WM_NCCREATE is received. The message is sent to the window's procedure callback during window creation.
Example:
case WM_NCCREATE:
{
if (!EnableNonClientDpiScaling(hWnd))
{
// Error handling
return FALSE;
}
return DefWindowProcW(...);
}
If the application's DPI-awareness context is DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2, then calling EnableNonClientDpiScaling should be omitted, as it won't have any effect, although the function will still return successfully.
From the documentation:
Non-client scaling for top-level windows is not enabled by default. You must call this API to enable it for each individual top-level window for which you wish to have the non-client area scale automatically. Once you do, there is no way to disable it. Enabling non-client scaling means that all the areas drawn by the system for the window will automatically scale in response to DPI changes on the window. That includes areas like the caption bar, the scrollbars, and the menu bar. You want to call EnableNonClientDpiScaling when you want the operating system to be responsible for rendering these areas automatically at the correct size based on the API of the monitor.
See this blog post for additional information about DPI scaling changes in Windows 10 AU.
Does anyone how the devs at MS did this?
This has a pretty disappointing answer. Using Alin Constantin's WinCheat and inspecting the top-level window of Calculator, I see a window size of 320x576, and a client size that is also 320x576.
In other words, Microsoft entirely avoids the problem by suppressing the non-client area of the window, putting everything in the client area instead. Making this work well for you may involve custom drawing of the title bar.
Something worth noting is that Calculator and e.g. Windows Explorer don't use the same colour for the title bars. Calculator doing custom drawing of the title bar would explain that perfectly.
UPDATE:
It is enough to add new <dpiAwarness> declaration to manifest to solve all this mess. Example is here.
Remnants of former investigations (obsolete):
More investigations on the subject.
System setup: two monitors, one is 96 dpi another one is 267 dpi (Microsoft Surface 4).
Testing window is moved to secondary 96 dpi monitor:
Here is rendering (wrong, IMO) with <dpiAware>true/pm</dpiAware> in manifest:
Note huge size of caption bar and wrong sizes of window icons.
And here is correct rendering using <dpiAware>true</dpiAware>
And I suspect that MSDN documentation is plainly misleading about values of PROCESS_DPI_AWARENESS. I do not see any differences in messages and styles between <dpiAware>true</dpiAware> and <dpiAware>true/pm</dpiAware>. The later one just makes caption larger. In both case application receives WM_DPICHANGED message while moving between monitors with different DPI.
Sigh.
The documentation says:
Note that the non-client area of a per monitor–DPI aware application is not scaled by Windows, and will appear proportionately smaller on a high DPI display.
The Microsoft apps that you link to deal with this by removing the non-client area and making the client area cover the entire window.
How to scale font sizes based on current DPI settings in VC++/MFC applications ?
As of now when I change the DPI from 100% yo 150% the font sizes remain the same, although the icons will scale down based on the current dpi ..
Please suggest the best way for above problem.
In Windows Vista and 7, the OS tries to hide the DPI from your program and does adjustments behind the scenes. If you want your program to react properly to DPI changes you must follow the guidelines from Microsoft titled Creating a DPI-Aware Application.
By specifying the text and control sizes in DLU's. That happens by default though, so I assume you are generating dialogs dynamically or from a memory-based DLGTEMPLATE. If you, you're (pardon my French) screwed, because you'll have to muck about with converting DLU's to pixels, a very painful and tedious process. Read the following KB articles:
http://support.microsoft.com/default.aspx?scid=kb;en-us;125681
http://support.microsoft.com/default.aspx?scid=kb;en-us;145994
Don't use DPI for font scaling. Instead, use the settings the user has configured in the "Appearance" section of Control Panel.
You might also want to consider making the font size configurable for just your application.