我从 2015 年开始更新我的答案。这是一些使用 Windows 10 中最新 DPI 功能的实用程序代码（特别是 GetDpiForWindow function，这是唯一支持窗口/应用程序/进程等的 DPI_AWARENESS 的方法）但回退到旧版本（每台显示器的 dpi 和桌面 dpi），因此它仍应适用于 Windows 7。
它不依赖于 WPF 和 Winforms，只依赖于 Windows 本身。
// note this class considers dpix = dpiy
public static class DpiUtilities
{
// you should always use this one and it will fallback if necessary
// https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getdpiforwindow
public static int GetDpiForWindow(IntPtr hwnd)
{
var h = LoadLibrary("user32.dll");
var ptr = GetProcAddress(h, "GetDpiForWindow"); // Windows 10 1607
if (ptr == IntPtr.Zero)
return GetDpiForNearestMonitor(hwnd);
return Marshal.GetDelegateForFunctionPointer<GetDpiForWindowFn>(ptr)(hwnd);
}
public static int GetDpiForNearestMonitor(IntPtr hwnd) => GetDpiForMonitor(GetNearestMonitorFromWindow(hwnd));
public static int GetDpiForNearestMonitor(int x, int y) => GetDpiForMonitor(GetNearestMonitorFromPoint(x, y));
public static int GetDpiForMonitor(IntPtr monitor, MonitorDpiType type = MonitorDpiType.Effective)
{
var h = LoadLibrary("shcore.dll");
var ptr = GetProcAddress(h, "GetDpiForMonitor"); // Windows 8.1
if (ptr == IntPtr.Zero)
return GetDpiForDesktop();
int hr = Marshal.GetDelegateForFunctionPointer<GetDpiForMonitorFn>(ptr)(monitor, type, out int x, out int y);
if (hr < 0)
return GetDpiForDesktop();
return x;
}
public static int GetDpiForDesktop()
{
int hr = D2D1CreateFactory(D2D1_FACTORY_TYPE.D2D1_FACTORY_TYPE_SINGLE_THREADED, typeof(ID2D1Factory).GUID, IntPtr.Zero, out ID2D1Factory factory);
if (hr < 0)
return 96; // we really hit the ground, don't know what to do next!
factory.GetDesktopDpi(out float x, out float y); // Windows 7
Marshal.ReleaseComObject(factory);
return (int)x;
}
public static IntPtr GetDesktopMonitor() => GetNearestMonitorFromWindow(GetDesktopWindow());
public static IntPtr GetShellMonitor() => GetNearestMonitorFromWindow(GetShellWindow());
public static IntPtr GetNearestMonitorFromWindow(IntPtr hwnd) => MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
public static IntPtr GetNearestMonitorFromPoint(int x, int y) => MonitorFromPoint(new POINT { x = x, y = y }, MONITOR_DEFAULTTONEAREST);
private delegate int GetDpiForWindowFn(IntPtr hwnd);
private delegate int GetDpiForMonitorFn(IntPtr hmonitor, MonitorDpiType dpiType, out int dpiX, out int dpiY);
private const int MONITOR_DEFAULTTONEAREST = 2;
[DllImport("kernel32", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr LoadLibrary(string lpLibFileName);
[DllImport("kernel32", CharSet = CharSet.Ansi, SetLastError = true)]
private static extern IntPtr GetProcAddress(IntPtr hModule, string lpProcName);
[DllImport("user32")]
private static extern IntPtr MonitorFromPoint(POINT pt, int flags);
[DllImport("user32")]
private static extern IntPtr MonitorFromWindow(IntPtr hwnd, int flags);
[DllImport("user32")]
private static extern IntPtr GetDesktopWindow();
[DllImport("user32")]
private static extern IntPtr GetShellWindow();
[StructLayout(LayoutKind.Sequential)]
private partial struct POINT
{
public int x;
public int y;
}
[DllImport("d2d1")]
private static extern int D2D1CreateFactory(D2D1_FACTORY_TYPE factoryType, [MarshalAs(UnmanagedType.LPStruct)] Guid riid, IntPtr pFactoryOptions, out ID2D1Factory ppIFactory);
private enum D2D1_FACTORY_TYPE
{
D2D1_FACTORY_TYPE_SINGLE_THREADED = 0,
D2D1_FACTORY_TYPE_MULTI_THREADED = 1,
}
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown), Guid("06152247-6f50-465a-9245-118bfd3b6007")]
private interface ID2D1Factory
{
int ReloadSystemMetrics();
[PreserveSig]
void GetDesktopDpi(out float dpiX, out float dpiY);
// the rest is not implemented as we don't need it
}
}
public enum MonitorDpiType
{
Effective = 0,
Angular = 1,
Raw = 2,
}