WM_COPYDATA Overview  Group

The WM_COPYDATA message is sent when an application passes data to another application.

WM_COPYDATA 

wParam = (WPARAM) (HWND) hwnd;            // handle of sending window 

lParam = (LPARAM) (PCOPYDATASTRUCT) pcds; // pointer to structure with data 

 

Parameters

hwnd

Identifies the window passing the data.

pcds

Points to a COPYDATASTRUCT structure that contains the data to be passed.

Return Values

If the receiving application processes this message, it should return TRUE; otherwise, it should return FALSE.

Remarks

An application must use the SendMessage function to send this message, not the PostMessage function.

The data being passed must not contain pointers or other references to objects not accessible to the application receiving the data.

While this message is being sent, the referenced data must not be changed by another thread of the sending process.

The receiving application should consider the data read-only. The pcds parameter is valid only during the processing of the message. The receiving application should not free the memory referenced by pcds. If the receiving application must access the data after SendMessage returns, it must copy the data into a local buffer.

See Also

PostMessage, SendMessage, COPYDATASTRUCT