Getting the mouse coordinates in the WM_LBUTTONDOWN message
c++, winapi
Solution
In the process function, why it doesn't pass the POINT variable to process function, and how to find mouse's POINT ?
There are separate functions to retrieve that information if you really want it. Most message handlers don't deal with mouse input, and there's no point in passing around extra arguments for message handlers that will almost never use them. (Arguably `WndProc` could have been defined to take a `MSG*`; I don't know the reason for its design, but I'd guess that members were added to the `MSG` structure over time.)
By GetCursorPos() ?
No. `GetCursorPos` will return the current position of the cursor, which might be different from the position when the message was generated. You instead want `GetMessagePos`. (This is analogous to `GetAsyncKeyState` versus `GetKeyState`.)
Similarly, a message handler can obtain the message time through `GetMessageTime`.
Problem
the structure of `MSG` as followed: ``` typedef struct tagMSG { HWND hwnd; UINT message; WPARAM wParam; LPARAM lParam; DWORD time; POINT pt; } MSG, *PMSG; ``` the message procedure as followed: ``` long WINAPI WndProc(HWND hWnd, UINT iMessage, UINT wParam, LONG lParam) ``` My Question: In the message procedure, why it doesn't pass the `POINT` variable to window procedure, and how to find mouse's `POINT` ? By `GetCursorPos()` ? I find some example get it by `LOWORD(lParam), HIWORD(lParam)` directly.. can you tell me the information about it ? thank you... i had see someone write this, is it right ? i not sure: ``` RECT rect1; long WINAPI WndProc(HWND hWnd,UINT iMessage,UINT wParam,LONG lParam) { HDC hDC; WORD x,y; PAINTSTRUCT ps; x = LOWORD(lParam); y = HIWORD(lParam); switch(iMessage) { case WM_LBUTTONDOWN: if(wParam&MK_CONTROL) { rect1.left = x; rect1.top = y; } else if(wParam&MK_SHIFT) { rect1.left = x; rect1.top = y; } break; case WM_DESTROY: PostQuitMessage(0); return 0; default: return(DefWindowProc(hWnd,iMessage,wParam,lParam)); } return 0; } ```