How to implement "teamviewer quickconnect"-like button into foreign window? - winapi

Question

I'd like to put a button in a foreign windows' title bar, much like Teamviewer does with the Quickconnect feature, or like Chrome has one in the top-right for switching users.
I know this is a repeat of How is Teamviewers Quickconnect button accomplished?
I'm just wondering if it would be possible to get a working example or a link to an open-source program that implements this. The answers given there are rather advanced for me. As in, how am I supposed to "hook" and "intercept" WM_NCPAINT message and so on.

Answer 1

This is the most simple example i can develop:
You need Visual Studio, add 2 project to the solution:
first project (HookDLL) is a dll project, second (Running app) is a win32 console project
in main.cpp (at project Running app) add this:
__declspec(dllimport) void RunHook();
int _tmain(int argc, _TCHAR* argv[])
{
RunHook();
return 0;
}
in dllmain button.cpp (at HookDLL project) add this code:
#include <Windows.h>
#include <stdio.h>
HINSTANCE hinstDLL;
HHOOK hhook_wndproc;
HWND b = NULL;
HBRUSH blue_brush = NULL, yellow_brush, red_brush;
int button_status = 0;
LRESULT CALLBACK DefaultWindowProc(HWND hwnd, UINT Msg, WPARAM wParam, LPARAM lParam)
{
switch(Msg)
{
case WM_CREATE:
if(!blue_brush)
{
blue_brush = CreateSolidBrush(RGB(0, 0, 255));
yellow_brush = CreateSolidBrush(RGB(255, 255, 0));
red_brush = CreateSolidBrush(RGB(255, 0, 0));
}
break;
case WM_PAINT:
{
HBRUSH b;
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
switch(button_status)
{
case 0:
b = blue_brush;
break;
case 1:
b = yellow_brush;
break;
default:
b = red_brush;
}
FillRect(hdc, &ps.rcPaint, b);
EndPaint(hwnd, &ps);
}
return 0;
case WM_MOUSEMOVE:
if(button_status == 0)
{
SetTimer(hwnd, 1, 100, NULL);
button_status = 1;
InvalidateRect(hwnd, NULL, false);
}
return 0;
case WM_TIMER:
{
POINT pt;
GetCursorPos(&pt);
if(button_status == 1 && WindowFromPoint(pt) != hwnd)
{
KillTimer(hwnd, 1);
button_status = 0;
InvalidateRect(hwnd, NULL, false);
}
}
return 0;
case WM_MOUSELEAVE:
button_status = 0;
InvalidateRect(hwnd, NULL, false);
return 0;
case WM_LBUTTONDOWN:
button_status = 2;
InvalidateRect(hwnd, NULL, false);
return 0;
case WM_LBUTTONUP:
if(button_status == 2) MessageBox(GetParent(hwnd), "teamviewer like button clicked", "Message", MB_OK);
button_status = 1;
InvalidateRect(hwnd, NULL, false);
return 0;
}
return DefWindowProc(hwnd, Msg, wParam, lParam);
}
void InitButton(HWND parent, int xPos, int yPos)
{
WNDCLASS wc;
wc.style = 0;
wc.lpfnWndProc = DefaultWindowProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hinstDLL;
wc.hIcon = NULL;
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = NULL;
wc.lpszMenuName = NULL;
wc.lpszClassName = "DEFAULT_CLASS";
RegisterClass(&wc);
b = CreateWindowEx(WS_EX_TOOLWINDOW, "DEFAULT_CLASS", NULL, WS_BORDER | WS_POPUP | WS_VISIBLE, xPos, yPos, 20, 20, parent, NULL, hinstDLL, NULL);
}
LRESULT WINAPI HookCallWndProc(int nCode, WPARAM wParam, LPARAM lParam)
{
if(nCode >= 0 && lParam != 0)
{
CWPRETSTRUCT *msg = (CWPRETSTRUCT*)lParam;
if(!IsWindow(msg->hwnd) || (GetWindowLong(msg->hwnd, GWL_STYLE) & WS_CHILD) != 0) return CallNextHookEx(hhook_wndproc, nCode, wParam, lParam);
switch(msg->message)
{
case WM_SHOWWINDOW:
if(!b && msg->wParam != 0)
{
b = (HWND)1;// see NOTES 5
RECT a;
GetWindowRect(msg->hwnd, &a);
InitButton(msg->hwnd, a.right - 150, a.top);
}
break;
case WM_SIZE:
if(GetParent(b) == msg->hwnd)
{
RECT a;
GetWindowRect(msg->hwnd, &a);
SetWindowPos(b, 0, a.right - 150, a.top, 0, 0, SWP_NOSIZE | SWP_NOOWNERZORDER | SWP_NOZORDER);
}
break;
case WM_SIZING:
case WM_MOVING:
if(GetParent(b) == msg->hwnd)
{
RECT* lprc = (LPRECT) msg->lParam;
SetWindowPos(b, 0, lprc->right - 150, lprc->top, 0, 0, SWP_NOSIZE | SWP_NOOWNERZORDER | SWP_NOZORDER);
}
}
}
return CallNextHookEx(hhook_wndproc, nCode, wParam, lParam);
}
__declspec(dllexport) void RunHook()
{
hhook_wndproc = SetWindowsHookEx(WH_CALLWNDPROCRET, HookCallWndProc, hinstDLL, 0);
char aux[10];
gets_s(aux);
UnhookWindowsHookEx(hhook_wndproc);
}
BOOL APIENTRY DllMain( HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
hinstDLL = hModule;
break;
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
Now, make dll project depedent of running app project in project->project dependencies:
NOTES:
1) i dont use NC paint code, because not always works, if windows buffer non client region, erases customized NC paint buttons
2) in 64 bits enviroment, you need to run a 32 bits hook for 32 bits apps, and other hook for 64 bits apps
3) YOU CAN NOT DEBUG YOUR HOOK WHEN IS CONNECTED TO ANOTHER PROCCESS, i suggest you debug it with a windows in your app and thread, and test it late in another proccess when is working
4) i use a button like approach for simplicity
5) this line
b = (HWND)1;
I use it for "solve" a multi thread problem, i suggest you make better code (syncronization) this case
HOW THIS WORKS:
run the app
when it start install a hook
open any other app (same 32/64 bits, see NOTE 2)
you must see a blue button at left side of title bar
click it and see a message box
for finish hook: just press ENTER at console window
CODE FLOW:
Running app just calls RunHook() procedure in dll, and dll do the work
RunHook() in dll starts a hook HookCallWndProc (global)
HookCallWndProc captures required message and creates the window button using InitButton() procedure
DefaultWindowProc handles button message