Drawing a line to a handle process

[psynchronized]

I want to draw a line in a solitaire process, or any process in general, but it doesnt work. I've managed to get the code from a drawing tutorial, but im not experienced at that, plus it's very hard to find any tutorials on c++ graphics, so any help would be really appreciated. here's my code:

#include <Windows.h>
#include <iostream>


int main()
{
	HDC hdc;
	HWND app = FindWindow(0, "Solitaire");
	DWORD id;
	GetWindowThreadProcessId(app, &id);
	HANDLE handle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, id);
	PAINTSTRUCT ps;
	hdc = BeginPaint(app, &ps);
	HPEN hPen,hOldPen;
	COLORREF xio = RGB(255,0,0);
	hPen = CreatePen(PS_SOLID, 10 , xio);
	hOldPen = (HPEN)SelectObject(hdc, hPen);

	MoveToEx(hdc,100,100,NULL);
	LineTo(hdc,250,500);

	system("pause");
	

}

[webJose]

You can only use BeginPaint() in the context of a WM_PAINT message. That's plain wrong right away.

Now I have never ever tried to do something like this, so I'll just say and you try: Change BeginPaint() for GetDC(NULL) to get a DC for the entire screen. See if you can draw in it. If you can, then use that. Just make sure you calculate the coordinates right.

[psynchronized]

thanks it works! i've just changed to GetDC(app).