How to get window control by position (win32 API)? - c++

Question

Is there a way to get the control handle using the coordinate position of the control? In other words, is there a way to find the control in the window area provided that we know its coordinate position?

Answer 1

You can use WindowFromPoint:
Here is the sample:
#include <Windows.h>
#include <iostream>
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE hPrevInstance, _In_ LPSTR szCmdLine, _In_ int iCmdShow)
{
static TCHAR szAppName[] = TEXT("hello windows");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("This program requires Windows NT!"), szAppName, MB_ICONERROR);
}
hwnd = CreateWindow(szAppName,
TEXT("the hello program"),
WS_OVERLAPPEDWINDOW,
100,
100,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL);
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while (GetMessageW(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessageW(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
POINT pt;
char bf[100];
HWND h;
HDC hdc;
RECT rc;
case WM_LBUTTONDOWN:
pt.x = 10;
pt.y = 10;
hdc = GetDC(hwnd);
h = WindowFromPoint(pt);
GetClientRect(hwnd, &rc);
sprintf_s(bf, 100, "%p\n", h);
TextOut(hdc,rc.right/2,rc.bottom/2,bf,strlen(bf));
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
When I press the left button, the handle for setting the coordinates is displayed in the middle of the screen.