How do I find position of a Win32 control/window relative to its parent window?

Question

Given handle of a Win32 window, I need to find position of it relative to its parent window.

I know several functions (e.g.; GetWindowRect() and GetClientRect()), bu

Answer 1

I know it's been answered before, but it's much easier to just get a child window's rect in screen coordinates, get it's position (POINT ptCWPos = {rectCW.left, rectCW.top};) and use the ScreenToClient() function, that will transform the screen coordinate point to the window's client coordinate point:

PS: I know that looks like a lot more code, but most of it is fiddling with the rect position; in most cases one will actually need the rect position rather than the whole rect.

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HWND hwndCW, hwndPW; // the child window hwnd
                     // and the parent window hwnd
RECT rectCW;
GetWindowRect(hwndCW, &rectCW); // child window rect in screen coordinates
POINT ptCWPos = { rectCW.left, rectCW.top };
ScreenToClient(hwndPW, &ptCWPos); // transforming the child window pos
                                  // from screen space to parent window space
LONG iWidth, iHeight;
iWidth = rectCW.right - rectCW.left;
iHeight = rectCW.bottom - rectCW.top;

rectCW.left = ptCWPos.x;
rectCW.top = ptCWPos.y;
rectCW.right = rectCW.left + iWidth;
rectCW.bottom = rectCW.right + iHeight; // child window rect in parent window space