MS Spy++ style Window Finder

#include "WindowFinder.h"
#include "main.h"
#include "resource.h"

#define BULLSEYE_CENTER_X_OFFSET		15
#define BULLSEYE_CENTER_Y_OFFSET		18





// Synopsis :
// 1. This routine launches the "Search Window" dialog box.
//
// 2. The dialog box is a MODAL dialog box that will not return until the user 
// clicks on the "OK" or "Cancel" button.
long StartSearchWindowDialog (HWND hwndMain)
{
  long lRet = 0;

  lRet = (long)DialogBox
  (
    (HINSTANCE)g_hInst, // handle to application instance 
    (LPCTSTR)MAKEINTRESOURCE(IDD_DIALOG_SEARCH_WINDOW), // identifies dialog box template 
    (HWND)hwndMain, // handle to owner window 
    (DLGPROC)SearchWindowDialogProc // pointer to dialog box procedure 
  );

  return lRet;
}





// Synopsis :
// 1. This function checks a hwnd to see if it is actually the "Search Window" Dialog's or Main Window's
// own window or one of their children. If so a FALSE will be returned so that these windows will not
// be selected. 
//
// 2. Also, this routine checks to see if the hwnd to be checked is already a currently found window.
// If so, a FALSE will also be returned to avoid repetitions.
BOOL CheckWindowValidity (HWND hwndDialog, HWND hwndToCheck)
{
  HWND hwndTemp = NULL;
  BOOL bRet = TRUE;

  // The window must not be NULL.
  if (hwndToCheck == NULL)
  {
    bRet = FALSE;
	goto CheckWindowValidity_0;
  }

  // It must also be a valid window as far as the OS is concerned.
  if (IsWindow(hwndToCheck) == FALSE)
  {
    bRet = FALSE;
	goto CheckWindowValidity_0;
  }

  // Ensure that the window is not the current one which has already been found.
  if (hwndToCheck == g_hwndFoundWindow)
  {
    bRet = FALSE;
	goto CheckWindowValidity_0;
  }

  // It must also not be the main window itself.
  if (hwndToCheck == g_hwndMainWnd)
  {
    bRet = FALSE;
	goto CheckWindowValidity_0;
  }
  
  // It also must not be the "Search Window" dialog box itself.
  if (hwndToCheck == hwndDialog)
  {
    bRet = FALSE;
	goto CheckWindowValidity_0;
  }

  // It also must not be one of the dialog box's children...
  hwndTemp = GetParent (hwndToCheck);
  if ((hwndTemp == hwndDialog) || (hwndTemp == g_hwndMainWnd))
  {
    bRet = FALSE;
	goto CheckWindowValidity_0;
  }

CheckWindowValidity_0:

  return bRet;
}





// Synopsis :
// 1. This is the handler for WM_MOUSEMOVE messages sent to the "Search Window" dialog proc.
//
// 2. Note that we do not handle every WM_MOUSEMOVE message sent. Instead, we check to see 
// if "g_bStartSearchWindow" is TRUE. This BOOL will be set to TRUE when the Window
// Searching Operation is actually started. See the WM_COMMAND message handler in 
// SearchWindowDialogProc() for more details.
//
// 3. Because the "Search Window" dialog immediately captures the mouse when the Search Operation 
// is started, all mouse movement is monitored by the "Search Window" dialog box. This is 
// regardless of whether the mouse is within or without the "Search Window" dialog. 
//
// 4. One important note is that the horizontal and vertical positions of the mouse cannot be 
// calculated from "lParam". These values can be inaccurate when the mouse is outside the
// dialog box. Instead, use the GetCursorPos() API to capture the position of the mouse.
long DoMouseMove 
(
  HWND hwndDialog, 
  UINT message, 
  WPARAM wParam, 
  LPARAM lParam
)
{
  POINT		screenpoint;
  HWND		hwndFoundWindow = NULL;
  char		szText[256];
  long		lRet = 0;

  // Must use GetCursorPos() instead of calculating from "lParam".
  GetCursorPos (&screenpoint);  

  // Display global positioning in the dialog box.
  wsprintf (szText, "%d", screenpoint.x);
  SetDlgItemText (hwndDialog, IDC_STATIC_X_POS, szText);
  
  wsprintf (szText, "%d", screenpoint.y);
  SetDlgItemText (hwndDialog, IDC_STATIC_Y_POS, szText);

  // Determine the window that lies underneath the mouse cursor.
  hwndFoundWindow = WindowFromPoint (screenpoint);

  // Check first for validity.
  if (CheckWindowValidity (hwndDialog, hwndFoundWindow))
  {
    // We have just found a new window.

    // Display some information on this found window.
	DisplayInfoOnFoundWindow (hwndDialog, hwndFoundWindow);

    // If there was a previously found window, we must instruct it to refresh itself. 
	// This is done to remove any highlighting effects drawn by us.
    if (g_hwndFoundWindow)
    {
      RefreshWindow (g_hwndFoundWindow);
    }

    // Indicate that this found window is now the current global found window.
    g_hwndFoundWindow = hwndFoundWindow;

    // We now highlight the found window.
    HighlightFoundWindow (hwndDialog, g_hwndFoundWindow);
  }

  return lRet;
}





// Synopsis :
// 1. Handler for WM_LBUTTONUP message sent to the "Search Window" dialog box.
// 
// 2. We restore the screen cursor to the previous one.
//
// 3. We stop the window search operation and release the mouse capture.
long DoMouseUp
(
  HWND hwndDialog, 
  UINT message, 
  WPARAM wParam, 
  LPARAM lParam
)
{
  long lRet = 0;

  // If we had a previous cursor, set the screen cursor to the previous one.
  // The cursor is to stay exactly where it is currently located when the 
  // left mouse button is lifted.
  if (g_hCursorPrevious)
  {
    SetCursor (g_hCursorPrevious);
  }

  // If there was a found window, refresh it so that its highlighting is erased. 
  if (g_hwndFoundWindow)
  {
    RefreshWindow (g_hwndFoundWindow);
  }

  // Set the bitmap on the Finder Tool icon to be the bitmap with the bullseye bitmap.
  SetFinderToolImage (hwndDialog, TRUE);

  // Very important : must release the mouse capture.
  ReleaseCapture ();

  // Make the main window appear normally.
  ShowWindow (g_hwndMainWnd, SW_SHOWNORMAL);

  // Set the global search window flag to FALSE.
  g_bStartSearchWindow = FALSE;

  return lRet;
}





// Synopsis :
// 1. This routine sets the Finder Tool icon to contain an appropriate bitmap.
//
// 2. If bSet is TRUE, we display the BullsEye bitmap. Otherwise the empty window
// bitmap is displayed.
BOOL SetFinderToolImage (HWND hwndDialog, BOOL bSet)
{
  HBITMAP hBmpToSet = NULL;
  BOOL bRet = TRUE;

  if (bSet)
  {
    // Set a FILLED image.
	hBmpToSet = g_hBitmapFinderToolFilled;
  }
  else
  {
    // Set an EMPTY image.
	hBmpToSet = g_hBitmapFinderToolEmpty;
  }

  SendDlgItemMessage
  (
    (HWND)hwndDialog, // handle of dialog box 
    (int)IDC_STATIC_ICON_FINDER_TOOL, // identifier of control 
    (UINT)STM_SETIMAGE, // message to send 
    (WPARAM)IMAGE_BITMAP, // first message parameter 
    (LPARAM)hBmpToSet // second message parameter 
  );

  return bRet;
}





// Synopsis :
// 1. This routine moves the mouse cursor hotspot to the exact 
// centre position of the bullseye in the finder tool static control.
//
// 2. This function, when used together with DoSetFinderToolImage(),
// gives the illusion that the bullseye image has indeed been transformed
// into a cursor and can be moved away from the Finder Tool Static
// control.
BOOL MoveCursorPositionToBullsEye (HWND hwndDialog)
{
  BOOL bRet = FALSE;
  HWND hwndToolFinder = NULL;
  RECT rect;
  POINT screenpoint;

  // Get the window handle of the Finder Tool static control.
  hwndToolFinder = GetDlgItem (hwndDialog, IDC_STATIC_ICON_FINDER_TOOL);

  if (hwndToolFinder)
  {
    // Get the screen coordinates of the static control,
	// add the appropriate pixel offsets to the center of 
	// the bullseye and move the mouse cursor to this exact
	// position.
    GetWindowRect (hwndToolFinder, &rect);
	screenpoint.x = rect.left + BULLSEYE_CENTER_X_OFFSET;
    screenpoint.y = rect.top + BULLSEYE_CENTER_Y_OFFSET;
	SetCursorPos (screenpoint.x, screenpoint.y);
  }

  return bRet;
}





// Synopsis :
// 1. This function starts the window searching operation.
//
// 2. A very important part of this function is to capture 
// all mouse activities from now onwards and direct all mouse 
// messages to the "Search Window" dialog box procedure.
long SearchWindow (HWND hwndDialog)
{
  long lRet = 0;

  // Set the global "g_bStartSearchWindow" flag to TRUE.
  g_bStartSearchWindow = TRUE;

  // Display the empty window bitmap image in the Finder Tool static control.
  SetFinderToolImage (hwndDialog, FALSE);

  MoveCursorPositionToBullsEye (hwndDialog);

  // Set the screen cursor to the BullsEye cursor.
  if (g_hCursorSearchWindow)
  {
    g_hCursorPrevious = SetCursor (g_hCursorSearchWindow);
  }
  else
  {
    g_hCursorPrevious = NULL;
  }

  // Very important : capture all mouse activities from now onwards and
  // direct all mouse messages to the "Search Window" dialog box procedure.
  SetCapture (hwndDialog);

  // Hide the main window.
  ShowWindow (g_hwndMainWnd, SW_HIDE);
  
  return lRet;
}





long DisplayInfoOnFoundWindow (HWND hwndDialog, HWND hwndFoundWindow)
{
  RECT		rect;              // Rectangle area of the found window.
  char		szText[256];
  char		szClassName[100];
  long		lRet = 0;

  // Get the screen coordinates of the rectangle of the found window.
  GetWindowRect (hwndFoundWindow, &rect);

  // Get the class name of the found window.
  GetClassName (hwndFoundWindow, szClassName, sizeof (szClassName) - 1);

  // Display some information on the found window.
  wsprintf
  (
    szText, "Window Handle == 0x%08X.\r\nClass Name : %s.\r\nRECT.left == %d.\r\nRECT.top == %d.\r\nRECT.right == %d.\r\nRECT.bottom == %d.\r\n",
    hwndFoundWindow,
	szClassName, 
    rect.left,
    rect.top,
    rect.right,
    rect.bottom
  );

  SetDlgItemText (hwndDialog, IDC_EDIT_STATUS, szText);

  return lRet;
}





long RefreshWindow (HWND hwndWindowToBeRefreshed)
{
  long lRet = 0;

  InvalidateRect (hwndWindowToBeRefreshed, NULL, TRUE);
  UpdateWindow (hwndWindowToBeRefreshed);
  RedrawWindow (hwndWindowToBeRefreshed, NULL, NULL, RDW_FRAME | RDW_INVALIDATE | RDW_UPDATENOW | RDW_ALLCHILDREN);

  return lRet;
}





// Performs a highlighting of a found window.
// Comments below will demonstrate how this is done.
long HighlightFoundWindow (HWND hwndDialog, HWND hwndFoundWindow)
{
  HDC		hWindowDC = NULL;  // The DC of the found window.
  HGDIOBJ	hPrevPen = NULL;   // Handle of the existing pen in the DC of the found window.
  HGDIOBJ	hPrevBrush = NULL; // Handle of the existing brush in the DC of the found window.
  RECT		rect;              // Rectangle area of the found window.
  long		lRet = 0;

  // Get the screen coordinates of the rectangle of the found window.
  GetWindowRect (hwndFoundWindow, &rect);

  // Get the window DC of the found window.
  hWindowDC = GetWindowDC (hwndFoundWindow);

  if (hWindowDC)
  {
    // Select our created pen into the DC and backup the previous pen.
    hPrevPen = SelectObject (hWindowDC, g_hRectanglePen);

    // Select a transparent brush into the DC and backup the previous brush.
    hPrevBrush = SelectObject (hWindowDC, GetStockObject(HOLLOW_BRUSH));

    // Draw a rectangle in the DC covering the entire window area of the found window.
    Rectangle (hWindowDC, 0, 0, rect.right - rect.left, rect.bottom - rect.top);

    // Reinsert the previous pen and brush into the found window's DC.
    SelectObject (hWindowDC, hPrevPen);

    SelectObject (hWindowDC, hPrevBrush);

    // Finally release the DC.
    ReleaseDC (hwndFoundWindow, hWindowDC);
  }

  return lRet;
}





BOOL CALLBACK SearchWindowDialogProc
(
  HWND hwndDlg, // handle to dialog box 
  UINT uMsg, // message 
  WPARAM wParam, // first message parameter 
  LPARAM lParam // second message parameter 
)
{
  BOOL bRet = FALSE;  // Default return value.

  switch (uMsg)
  {
    case WM_INITDIALOG :
	{
	  bRet = TRUE;
	  break;
	}

	case WM_MOUSEMOVE :
	{
      bRet = TRUE;

	  if (g_bStartSearchWindow)
	  {
	    // Only when we have started the Window Searching operation will we 
		// track mouse movement.
	    DoMouseMove(hwndDlg, uMsg, wParam, lParam);
	  }

	  break;
	}

	case WM_LBUTTONUP :
	{
      bRet = TRUE;

	  if (g_bStartSearchWindow)
	  {
	    // Only when we have started the window searching operation will we
		// be interested when the user lifts up the left mouse button.
	    DoMouseUp(hwndDlg, uMsg, wParam, lParam);
	  }

	  break;
	}

	case WM_COMMAND :
	{
      WORD wNotifyCode = HIWORD(wParam); // notification code 
      WORD wID = LOWORD(wParam);         // item, control, or accelerator identifier 
      HWND hwndCtl = (HWND)lParam;      // handle of control 

	  if ((wID == IDOK) || (wID == IDCANCEL))
	  {
	    bRet = TRUE;
	    EndDialog (hwndDlg, wID);
	  }

	  if (wID == IDC_STATIC_ICON_FINDER_TOOL)
	  {
	    // Because the IDC_STATIC_ICON_FINDER_TOOL static control is set with the SS_NOTIFY
		// flag, the Search Window's dialog box will be sent a WM_COMMAND message when this 
		// static control is clicked.
        bRet = TRUE;
		// We start the window search operation by calling the DoSearchWindow() function.
		SearchWindow(hwndDlg);
	    break;
	  }

	  break;
	}

	default :
	{
	  bRet = FALSE;
	  break;
	}
  }

  return bRet;
}