PhysicalToLogicalPoint function (winuser.h)

Article
11/19/2022

Converts the physical coordinates of a point in a window to logical coordinates.

Syntax

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

Parameters

[in] hWnd

Type: HWND

A handle to the window whose transform is used for the conversion. Top level windows are fully supported. In the case of child windows, only the area of overlap between the parent and the child window is converted.

[in, out] lpPoint

Type: LPPOINT

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

Return value

None

Remarks

Windows Vista introduces the concept of physical coordinates. Desktop Window Manager (DWM) scales non-dots per inch (dpi) aware windows when the display is high dpi. The window seen on the screen corresponds to the physical coordinates. The application continues to work in logical space. Therefore, the application's view of the window is different from that which appears on the screen. For scaled windows, logical and physical coordinates are different.

The function uses the window identified by the hWnd parameter and the physical coordinates given in the POINT structure to compute the logical coordinates. The logical coordinates are the unscaled coordinates that appear to the application in a programmatic way. In other words, the logical coordinates are the coordinates the application recognizes, which can be different from the physical coordinates. The API then replaces the physical coordinates with the logical coordinates. The new coordinates are in the world coordinates whose origin is (0, 0) on the desktop. The coordinates passed to the API have to be on the hWnd.

The source coordinates are in device units.

On all platforms, PhysicalToLogicalPoint will fail on a window that has either 0 width or height; an application must first establish a non-0 width and height by calling, for example, MoveWindow. On some versions of Windows (including Windows 7), PhysicalToLogicalPoint will still fail if MoveWindow has been called after a call to ShowWindow with SH_HIDE has hidden the window.

In Windows 8, system–DPI aware applications translate 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, PhysicalToLogicalPoint and LogicalToPhysicalPoint 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. In those cases, use PhysicalToLogicalPointForPerMonitorDPI and LogicalToPhysicalPointForPerMonitorDPI.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Target Platform	Windows
Header	winuser.h (include Windows.h)
Library	User32.lib
DLL	User32.dll
API set	ext-ms-win-ntuser-window-l1-1-1 (introduced in Windows 8.1)

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