LogicalToPhysicalPointForPerMonitorDPI function (winuser.h)

Converts a point in a window from logical coordinates into physical coordinates, regardless of the dots per inch (dpi) awareness of the caller. For more information about DPI awareness levels, see PROCESS_DPI_AWARENESS.

Syntax

BOOL LogicalToPhysicalPointForPerMonitorDPI(
  [in]      HWND    hWnd,
  [in, out] LPPOINT lpPoint
);

Parameters

[in] hWnd

A handle to the window whose transform is used for the conversion.

[in, out] lpPoint

A pointer to a POINT structure that specifies the logical coordinates to be converted. The new physical coordinates are copied into this structure if the function succeeds.

Return value

Returns TRUE if successful, or FALSE otherwise.

Remarks

In Windows 8, system–DPI aware applications translated between physical and logical space using PhysicalToLogicalPoint and LogicalToPhysicalPoint. In Windows 8.1, the additional virtualization of the system and inter-process communications means that for the majority of applications, you do not need these APIs. As a result, in Windows 8.1, these APIs no longer transform points. The system returns all points to an application in its own coordinate space. This behavior preserves functionality for the majority of applications, but there are some exceptions in which you must make changes to ensure that the application works as expected.

For example, an application might need to walk the entire window tree of another process and ask the system for DPI-dependent information about the window. By default, the system will return the information based on the DPI awareness of the caller. This is ideal for most applications. However, the caller might need the information based on the DPI awareness of the application associated with the window. This might be necessary because the two applications send DPI-dependent information between each other directly. In this case, the application can use LogicalToPhysicalPointForPerMonitorDPI to get physical coordinates and then use PhysicalToLogicalPointForPerMonitorDPI to convert the physical coordinates into logical coordinates based on the DPI-awareness of the provided HWND.

Consider two applications, one has a PROCESS_DPI_AWARENESS value of PROCESS_DPI_UNAWARE and the other has a value of PROCESS_PER_MONITOR_AWARE. The PROCESS_DPI_UNAWARE app creates a window on a single monitor where the scale factor is 200% (192 DPI). If both apps call GetWindowRect on this window, they will receive different values. The PROCESS_DPI_UNAWARE app will receive a rect based on 96 DPI coordinates, while the PROCESS_PER_MONITOR_AWARE app will receive coordinates matching the actual DPI of the monitor. If the PROCESS_PER_MONITOR_AWARE needs the rect that the system returned to the PROCESS_DPI_UNAWARE app, it could call LogicalToPhysicalPointForPerMonitorDPI for the corners of its rect and pass in the handle to the PROCESS_DPI_UNAWARE app's window. This will return points based on the other app's awareness that can be used to create a rect.

Requirements

See also

PROCESS_DPI_AWARENESS

PhysicalToLogicalPointForPerMonitorDPI