SetThreadDpiHostingBehavior function

Sets the thread's DPI_HOSTING_BEHAVIOR. This behavior allows windows created in the thread to host child windows with a different DPI_AWARENESS_CONTEXT.

Syntax

DPI_HOSTING_BEHAVIOR SetThreadDpiHostingBehavior(
  DPI_HOSTING_BEHAVIOR value
);

Parameters

value

The new DPI_HOSTING_BEHAVIOR value for the current thread.

Return Value

The previous DPI_HOSTING_BEHAVIOR for the thread. If the hosting behavior passed in is invalid, the thread will not be updated and the return value will be DPI_HOSTING_BEHAVIOR_INVALID. You can use this value to restore the old DPI_HOSTING_BEHAVIOR after overriding it with a predefined value.

Remarks

DPI_HOSTING_BEHAVIOR enables a mixed content hosting behavior, which allows parent windows created in the thread to host child windows with a different DPI_AWARENESS_CONTEXT value. This property only effects new windows created within this thread while the mixed hosting behavior is active. A parent window with this hosting behavior is able to host child windows with different DPI_AWARENESS_CONTEXT values, regardless of whether the child windows have mixed hosting behavior enabled.

This hosting behavior does not allow for windows with per-monitor DPI_AWARENESS_CONTEXT values to be hosted until windows with DPI_AWARENESS_CONTEXT values of system or unaware.

To avoid unexpected outcomes, a thread's DPI_HOSTING_BEHAVIOR should be changed to support mixed hosting behaviors only when creating a new window which needs to support those behaviors. Once that window is created, the hosting behavior should be switched back to its default value.

This API is used to change the thread's DPI_HOSTING_BEHAVIOR from its default value. This is only necessary if your app needs to host child windows from plugins and third-party components that do not support per-monitor-aware context. This is most likely to occur if you are updating complex applications to support per-monitor DPI_AWARENESS_CONTEXT behaviors.

Enabling mixed hosting behavior will not automatically adjust the thread's DPI_AWARENESS_CONTEXT to be compatible with legacy content. The thread's awareness context must still be manually changed before new windows are created to host such content.

Requirements

   
Minimum supported client Windows 10, version 1803 [desktop apps only]
Minimum supported server Windows Server 2016 [desktop apps only]
Target Platform Windows
Header winuser.h
Library User32.lib
DLL User32.dll

See Also

DPI_HOSTING_BEHAVIOR

GetThreadDpiHostingBehavior

GetWindowDpiHostingBehavior