Get Screen Size on C#

The process is running under DPI virtualization. So we should apply the DPI aware manifest option to stop DPI virtualization

[DllImport("user32.dll", SetLastError=true)]
static extern bool SetProcessDPIAware();

Then

public enum SystemMetric
{
    VirtualScreenWidth = 78, // CXVIRTUALSCREEN 0x0000004E 
    VirtualScreenHeight = 79, // CYVIRTUALSCREEN 0x0000004F 
}

[DllImport("user32.dll")]
public static extern int GetSystemMetrics(SystemMetric metric);

public static Size GetVirtualDisplaySize()
{
    var width = GetSystemMetrics(SystemMetric.VirtualScreenWidth);
    var height = GetSystemMetrics(SystemMetric.VirtualScreenHeight);

    return new Size(width, height);
}

References
https://stackoverflow.com/questions/28339257/getsystemmetrics-and-tscreen-returns-wrong-value
https://www.pinvoke.net/default.aspx/user32/SetProcessDPIAware.html
https://stackoverflow.com/questions/1317235/c-get-complete-desktop-size
https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setprocessdpiaware

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