Dealing with multiple DPI screens - c#

Let's suppose that I have two screens, side by side:
1920x1080 100% DPI
1360x768 125% DPI
For my Window, this means:
1920x1080: Ok
1088x614: Not ok, it's divided by 1,25 because of the scaling factor.
Turning into this:
1920x1080 + 1088x614: 3008x1080
I want to use the CopyFromScreen/BitBlt methods.
These methods ignore all DPI info, making the Left and Top properties (of a window, for example) useless if inside a high dpi screen. Or left to a high dpi screen, since it behaves like 1 screen, example:
So whenever I need to get a screen point from within a set of screens with at least one having a high DPI, it will return a smaller point.
Is there any way to get the true (by true, ignoring the scaling factor) XY info from a set of screens with (at least one) high DPI?
I already tried the managed PointToScreen and the unmanaged ClientToScreen methods, both resulting the same "right" point.
Please, read
I want to take screenshots of the screen based of the position of my Window.
I have two monitors, one with 100% DPI, other with 125% DPI.
If my Window is inside the 1st monitor, the screenshot based on the Left/Top properties of my Window works.
If my Window is inside the second monitor, the screenshot won't take the right spot!
Because
The BitBlt API method ignores the scaling of the screens. Example:
Screenshot of the point 100;100 will be right, because it's inside the 1st screen.
Screenshot of the point 1950;100 won't be right, because it's inside the 2nd screen. Notice that it's 30 pixels to the right.
Why?
As said earlier, for my app, the 125% DPI reduces the screen resolution to 1088x614, but for the BitBlt method, it is still 1360x768.
So I can't convert the Left/Top properties, because it will be wrong, since there is a 100% DPI screen to the left.
Example of the Left property:
I believe this is the right way to convert:
1920px + 50px: 100% + 125%: 1920 + 62: 1982px
And this is the proposed version:
1920px + 50px: 100% + 125%: 2400 + 62: 2462px
See, if I simple convert the current Left property based on the DPI of the current Window, on this case my second screen, I'll also be converting the values of my first screen. This should not happen.

Related

Unity - Window size depending on Screen size

I would like my game to have a 1:1 aspect ratio, but scaled up to a certain amount. Meaning that the width and height must be identical, but never larger than the actual screen size. Ontop of that, to ensure consistent pixel sizes the width and height values must be power of 2 value.
I didn't have any problems figuring out the needed value.
int value = 2;
int limit = Screen.currentResolution.height;
while (value * 2 < limit) value *= 2;
Debug.Log(value);
I much rather have no idea how to set the window size BEFORE the splash image is even shown. Is there any way how to do this?
Yes, there is, but that means that you'll need to get rid of the launch window.
The reason is that, if you enable the launch window (from which you can select resolutions, quality, windowed or fullscreen mode etc.), Unity will show only the video card available resolutions - and this means no 1:1 aspect ratio resolutions available.
So, in order to do this, you need to setup the Player Settings as follows:
The important part is to disable the Display Resolution Dialog.
Then you set the Default Screen Width and Height by disabling the Default Is Native Resolution.
Notice that the standalone will be forced to this, and only this, resolution at start - after the splash screen you can set whatever resolution you want by calling the Screen.SetResolution method from any script in the first scene loaded.
Of course you can make the standalone start in windowed or fullscreen mode, by unticking/ticking the Default Is Full Screen option.
That's pretty much it, if you wanted to give the user the option to choose from a list of 1:1 AR resolutions, you simply just can't at the moment afaik.
Edit: The resolution info of the Player Settings are stored in the registry inside HKEY_CURRENT_USER\Software\[YourCompanyName]\[YourGameName].
The 3 keys are these:
Screenmanager Is Fullscreen mode
Screenmanager Resolution Height
Screenmanager Resolution Width
To change those from inside the game at runtime, you need to use:
PlayerPrefs.SetInt("Screenmanager Is Fullscreen mode", [0/1]);
PlayerPrefs.SetInt("Screenmanager Resolution Height", [HeighthRes]);
PlayerPrefs.SetInt("Screenmanager Resolution Width", [WidthRes]);
These will be read the next time the game is launched, setting the starting resolution before the splash screen.

WPF: SystemParameters.WindowCaptionButtonHeight returns smaller number than expected

We have a window where we have set the WindowChrome GlassFrameThickness to a negative value so that we have glass frame extended over the entire window.
With this, the SystemParameters.WindowCaptionButtonHeight value returns 22 when I am actually expecting something in the range of ~36. I've provided some pictures showing what the current and expected behavior should be.
Current Behavior
Expected Behavior
Currently I am working around this issue by using the WindowCaptionButtonWidth instead of height since it returns the more expected value but this just feels wrong.
Under the DWM, these system parameters no longer give correct vales. You can still calculate the height by summing up SystemParameters.CaptionHeight, SystemParameters.WindowResizeBorderThickness.Left (or whatever other than Top), and SystemParameters.WindowNonClientFrameThickness.Left (or whatever other than Top).
However, things become quite complicated under Per-Monitor DPI environment like Windows 10. These system parameters turn to be useless without correct modifications by System DPI and Per-Monitor DPI. So, if you wish to completely redesign a window, the caption height will be a part of total considerations for Per-Monitor DPI.

Detect if non DPI-aware application has been scaled/virtualized

I'm trying to detect in a WinForms application if it has been launched in scaled/virtualized mode due to the OS having a high DPI. Currently, in a system running at 3840x2400 with 200% scaling, the application sees the resolution as 1920x1200, the DPI as 96, and the scale factor is 1.
We are in the process of making the application DPI-aware, but until then, we need a "quick fix" that will allow us to detect if scaled. The reason for this is that it breaks a functionality in the application that takes a screenshot. We use the scaled dimensions in Graphics.CopyFromScreen, it takes a screenshot of the wrong size since it is expecting the non-scaled dimensions.
I am aware of the DPI-awareness setting, but for the moment, we still want the application to be scaled, but be able to detect that we are scaled and get the non-scaled dimensions, if possible.
An application that is not explicitly marked as high-DPI aware will be lied to by the system and told that there are 96 DPI with a scaling factor of 100%. In order to get the real DPI settings, and avoid automatic virtualization by DWM, you will need to include <dpiAware>True/PM</dpiAware> in your application's manifest. More information is available here.
In your case, it sounds like you are looking for the LogicalToPhysicalPointForPerMonitorDPI and PhysicalToLogicalPointForPerMonitorDPI pair of functions. As the linked documentation explains, by default, the system will return information about other windows based on the DPI awareness of the caller. So if a non-DPI aware application tries to get the bounds of a window of a high-DPI aware process, it will get bounds that have been translated into its own non-DPI aware coordinate space. This would be, in the vernacular of these functions, the "logical" coordinates. You can convert these to "physical" coordinates, which are those that are actually used by the operating system (and other high-DPI aware processes).
To answer your actual question, though: If you absolutely need to break through the operating system's lies in a process that is not DPI aware, I can think of two ways to do so:
Call the GetScaleFactorForMonitor function. If the resulting DEVICE_SCALE_FACTOR value is anything other than SCALE_100_PERCENT, then you are scaled. If your application is not DPI aware, then you are being virtualized.
This is a quick-and-dirty solution, as a simple P/Invoke definition is all you need to call it from a WinForms application. However, you should not rely on its results for anything more than a Boolean "are we scaled/virtualized?" indicator. In other words, do not trust the scale factor that it returns!
On a Windows 10 system where the system DPI is 96, and a high-DPI monitor has a 144 DPI (150% scaling), the GetScaleFactorForMonitor function returns SCALE_140_PERCENT when it would be expected to return SCALE_150_PERCENT (144/96 == 1.5). I don't really understand why this is the case. The only thing I can figure out is that it was designed for Metro/Modern/UWP apps on Windows 8.1, where 150% is not a valid scale factor but 140% is. The scaling factors have since been unified in Windows 10, but this function appears not to have been updated and still returns unreliable results for desktop applications.
Calculate the scaling factor yourself, based on the logical and physical widths of the monitor.
First, of course, you'll need to obtain an HMONITOR (handle to a specific physical monitor). You can do this by calling MonitorFromWindow, passing a handle to your WinForms window, and specifying MONITOR_DEFAULTTONEAREST. That will get you a handle to the monitor that your window of interest is being displayed on.
Then, you'll use this monitor handle to get the logical width of that monitor by calling the GetMonitorInfo function. That fills in a MONITORINFOEX structure that contains, as one of its members, a RECT structure (rcMonitor) that contains the virtual-screen coordinates of that monitor. (Remember that, unlike .NET, the Windows API represents rectangles in terms of their left, top, right, and bottom extents. The width is the right extent minus the left extent, while the height is the bottom extent minus the top extent.)
The MONITORINFOEX structure filled in by GetMonitorInfo will also have given you the name of that monitor (the szDevice member). You can then use that name to call the EnumDisplaySettings function, which will fill in a DEVMODE structure with a bunch of information about the physical display modes for that monitor. The members you're interested in are dmPelsWidth and dmPelsHeight, which give you the number of physical pixels per width and height, respectively.
You can then divide the logical width by the physical width to determine the scaling factor for the width. Same thing for the height (except that all monitors I'm aware of have square pixels, so the vertical scaling factor will be equal to the horizontal scaling factor).
Example code, tested and working in Windows 10 (written in C++ because that's what I have handy; sorry you'll have to do your own translation to .NET):
// Get the monitor that the window is currently displayed on
// (where hWnd is a handle to the window of interest).
HMONITOR hMonitor = MonitorFromWindow(hWnd, MONITOR_DEFAULTTONEAREST);
// Get the logical width and height of the monitor.
MONITORINFOEX miex;
miex.cbSize = sizeof(miex);
GetMonitorInfo(hMonitor, &miex);
int cxLogical = (miex.rcMonitor.right - miex.rcMonitor.left);
int cyLogical = (miex.rcMonitor.bottom - miex.rcMonitor.top);
// Get the physical width and height of the monitor.
DEVMODE dm;
dm.dmSize = sizeof(dm);
dm.dmDriverExtra = 0;
EnumDisplaySettings(miex.szDevice, ENUM_CURRENT_SETTINGS, &dm);
int cxPhysical = dm.dmPelsWidth;
int cyPhysical = dm.dmPelsHeight;
// Calculate the scaling factor.
double horzScale = ((double)cxPhysical / (double)cxLogical);
double vertScale = ((double)cyPhysical / (double)cyLogical);
ASSERT(horzScale == vertScale);

Programmatically change ultrawide monitor resolution without stretching

I'm trying to write a little C# application to change between ultrawide resolution and 1920 x 1080.
I've been following this guide successfully: http://www.codeproject.com/Articles/36664/Changing-Display-Settings-Programmatically
And I have it changing between the resolutions. However, when switching to 1920 x 1080 I get a stretched view instead of a centered view on the monitor resolution.
I'm not seeing the appropriate flag in DEVMODE. Anyone know what settings I'm missing to center rather than stretch a monitor resolution?

How should i use VirtualScreenLeft and VirtualScreenTop

In my application i need to know size of all monitors combined space, to adjust size of the window if it goes to big.
I found VirtualScreenWidth and VirtualScreenHeight in System.Windows.SystemParameters and it seems like what i need. But also i wonder what is VirtualScreenLeft and VirtualScreenTop and how i should take it in consideration? In which scenarios this values are set to not 0?
The virtual screen is the bounding box containing all the monitors of the system. The bounding box is referenced at 0,0 being the upper-left corner of the main monitor (the main-monitor is defined in the system properties).
This means that the bounding box can have negative numbers as the Left/Top values. For example, lets say you have 2 1920x1080 monitors. The main monitor is set to the one on the right (but level at the top), the bounding box will be -1920,0,3840,1080 (x,y,w,h).
If you move the left monitor up 500 pixels, the bounding box becomes -1920,-500,3840,1580. Its important to note that some areas of the bounding box will not be visible to the user, so if you are designing a screen that takes up as much area as both monitors have, be aware that they may not be set up in a rectangular shape. They also may not be both the same resolution.

Categories