GetDpiForWindowhwnd

GetDpiForWindow is a Windows API function used to retrieve the DPI (dots per inch) value currently in effect for a specific window. It enables per-window DPI awareness by returning the DPI for the window’s display context, rather than a system-wide setting.

The function prototype is UINT GetDpiForWindow(HWND hWnd); where hWnd is a handle to the window for which the DPI is requested.

Return value and behavior: The function returns the window’s DPI as an unsigned integer, typically values like 96, 120, 144, etc. This reflects the DPI of the monitor on which the window is currently displayed and the process’s DPI awareness context. If the window’s DPI context cannot be determined, the value may reflect the system DPI.

Usage notes: GetDpiForWindow is useful for scaling UI elements to match the actual display density of a specific window, supporting accurate layout and rendering on multi-monitor setups with different DPIs. It is part of per-monitor DPI support introduced in Windows 10 and later. The function is intended for use in user interface code that must adapt to DPI changes at runtime.

Requirements and availability: GetDpiForWindow is available on Windows 10 and later. Include Windows.h in your source and link against User32.lib. The function complements other DPI APIs such as GetDpiForSystem and GetDpiForMonitor, which operate at different scopes than a single window.

Example usage: UINT dpi = GetDpiForWindow(hwnd); This value can be used to scale fonts, controls, and graphics to match the window’s current DPI. See also DPI awareness, per-monitor DPI, and related APIs for comprehensive DPI handling.