First, the message processing function of the overview control is defined by the system, usually, does not need to be provided. However, when the control is required to be specially controlled, a message processing function can be provided to replace the original message processing function. After your own processing is complete, call the default message processing of the control.
Second, related functions 1. The properties of the window class can be read and set by getWindowlong and SetWindowlong
Long getWindowlong
HWND HWND, // Handle to Window
INT NINDEX / / Offset of Value To Retrieve
);
Long setwindowlong
HWND HWND, // Handle to Window
INT NINDEX, // Offset of Value To Set
Long Dwnewlong // New Value
); You can return or set the following:
NINDEX value meaning
GWL_EXSTYLE extension style
GWL_Style style
GWL_WNDPROC message processing function
GWL_HINSTANCE instance
GWL_ID window ID
GWL_USERDATA user data
DWL_DLGPROC dialog message processing function
DWL_MSGRESULT
DWL_USER
Use
OldMsgProc = (WndProc) Setwindowlong (hcontrolwnd, gwl_wndproc, (long) mymsgproc); replacing the control message processing function into mymsgproc, the original processing function is recorded by the OldMSGProc.
2. Call message processing function
LResult CallWindowProc
WndProc LPPREVWNDFUNC, / / POINTER TO Previous Procedure
HWND HWND, // Handle to Window
Uint MSG, // Message
WPARAM WPARAM, // First Message Parameter
LParam lParam // Second Message Parameter
);
Third, example
1. Provide new processing functions
// Record global variables for the original handler
WndProc OldmsgProc;
// New message processing function
Lresult mymsgproc (hwnd hwnd, uint message, wparam wparam, lparam lparam)
{
Switch (Message)
{
Case WM_LBUTTONDOWN:
:: MessageBox (NULL, Click! "," ", MB_OK);
}
// Call the control of the controlled message processing function
Return CallWindowProc (OldmsgProc, Hwnd, Message, WPARAM, LPARAM);
}
2. After the window is created, change the message processing function.
Case WM_CREATE:
{
HWND HCONTROLWND = CREATEWINDOWEX (0, "Button",
Text ("button (& a)),
WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
10,
10,
100,
100,
HWnd,
(HMENU) 1000, // Control ID
(LpcreateStruct) LPARAM -> Hinstance, // Example handle
NULL);
/ / Embed a new message processing function
OldMsgProc = (WndProc) setwindowlong (hcontrolwnd, gwl_wndproc, (long) mymsgproc;
}
Return 0;
