How to duplicate a window's clientarea to another window? - c++

Question

I want to create a simple project (the language doesn't really matter/but I prefer C++) which simply takes a window title as it's input and duplicate it's visual part, bit by bit, to a new window. just like a mirror better I'd say.
As far as I remember there was a win32 API for this but I can't remember, so would you please tell me how can I achieve this?
And please tell me, will your answers work with DirectX/Open-GL applications as well or not?

Answer 1

You can get DC of first window, and get DC of second window. And after this do BitBlt or StretchBlt. It has to work... But I don't know what about DirectX/Open-Gl... I think it has to work too. But anyway. It won't take much time to check it.

Answer 2

Here is the source code for a program that will mirror other apps, you can use StretchBlt() instead of BitBlt(), this will not copy Menubars or popups.
Some apps like chrome, calculator, and camera use child windows for the visual part, and FindWindow() only scans through top-level windows for the title, so you can use FindWindowEx() with it to make that work!
#include <windows.h>
HWND sourceWindow;
void Mirror(HWND hwndSource, HWND hwndDst)
{
HDC source = GetDC(hwndSource);
HDC dst = GetDC(hwndDst);
RECT srcSiz;
GetClientRect(hwndSource, &srcSiz);
SetWindowPos(hwndDst, NULL, 0, 0, srcSiz.right, srcSiz.bottom, SWP_NOMOVE | SWP_NOZORDER);
BitBlt(dst, 0, 0, srcSiz.right, srcSiz.bottom, source, 0, 0, SRCCOPY);
ReleaseDC(hwndSource, source);
ReleaseDC(hwndDst, dst);
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
{
switch (Message)
{
case WM_CREATE:
SetTimer(hwnd, 1, 500, (TIMERPROC) NULL);//This will refresh after every 500 ms
break;
case WM_TIMER:
Mirror(sourceWindow, hwnd);
break;
case WM_DESTROY:
KillTimer(hwnd, 1);
break;
default:
return DefWindowProc(hwnd, Message, wParam, lParam);
}
return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG msg;
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(hInstance, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(CreateSolidBrush(RGB(0, 0, 0)));
wc.lpszMenuName = NULL;
wc.lpszClassName = "MyWindow";
wc.hIconSm = LoadIcon(hInstance, IDI_APPLICATION);
if (!RegisterClassEx(&wc))
{
MessageBox(NULL, "Window Registration Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
return 0;
}
hwnd = CreateWindowEx(WS_EX_OVERLAPPEDWINDOW, "MyWindow", "MyTitle", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 500, 500,
NULL, NULL, hInstance, NULL);
if (!hwnd)
{
MessageBox(NULL, "Window Creation Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
sourceWindow = FindWindowA(NULL, "<WindowTitle>");//or you can use class name
while(GetMessage(&msg, NULL, 0, 0) > 0)
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}