3 windows, cpu 100%

Hello Everyone
When I originally created three windows I did not realize that they were making my cpu run at 100% while my program was running. So I had been happily programming away but when I created even more windows with same child child class , my system is sticking almost freezing. So I tracked back through my versions to realize that the child windows must be the cause of the problem. I'm only creating the child windows once in the WM_CREATE part of winproc. I must be missing something obvious.Thanks for any replies.
phil

I'm using c
win2k
dev c++

Code:

---

/*------------------------------------------------------------
  V3_6
  ------------------------------------------------------------*/

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
LRESULT CALLBACK ChildWndProc (HWND, UINT, WPARAM, LPARAM) ;
LRESULT CALLBACK ChildChildWndProc (HWND, UINT, WPARAM, LPARAM) ;
HWND hwndChildChild;        // handle for child of child window
HWND hwndChild;        // handle for child window
TCHAR szChildClass[] = TEXT("Main_Child");
TCHAR szChildChildClass[] = TEXT("Child_Child");


int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
{
    static TCHAR szAppName[] = TEXT ("HelloWin") ;
    HWND        hwnd ;
    MSG          msg ;
    BOOL bRet;    // returm of getmessage

    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) ;
          return 0 ;
    }
    // Update winclass for main_child window .START
    // Then register class .START
    wndclass.lpfnWndProc    = ChildWndProc;
    wndclass.hIcon          = NULL;
    wndclass.hbrBackground  = (HBRUSH) GetStockObject (LTGRAY_BRUSH) ;
    wndclass.lpszClassName  = szChildClass;
    RegisterClass(&wndclass);
    // Update winclass for main_child window .FINISH
    // Then register class .FINISH

    // Update winclass for child_child window .START
    // Then register class .START
    wndclass.lpfnWndProc    = ChildChildWndProc;
    wndclass.hIcon          = NULL;
    wndclass.hbrBackground  = (HBRUSH) GetStockObject (GRAY_BRUSH) ;
    wndclass.lpszClassName  = szChildChildClass;
    RegisterClass(&wndclass);
    // Update winclass for child_child window .FINISH
    // Then register class .FINISH
   
    hwnd = CreateWindow (szAppName,                  // window class name
                          TEXT ("The Win Program"), // window caption
                          WS_OVERLAPPEDWINDOW |
                          WS_CLIPCHILDREN ,        // window style
                          CW_USEDEFAULT,              // initial x position
                          CW_USEDEFAULT,              // initial y position
                          CW_USEDEFAULT,              // initial x size
                          CW_USEDEFAULT,              // initial y size
                          NULL,                      // parent window handle
                          NULL,                      // window menu handle
                          hInstance,                  // program instance handle
                          NULL) ;                    // creation parameters
   
    ShowWindow (hwnd, iCmdShow) ;
    UpdateWindow (hwnd) ;
   
    while ((bRet = GetMessage (&msg, NULL, 0, 0))!=0)
    {
          if (bRet == -1)
          {
          MessageBox (NULL, TEXT ("Get message, error!"),
                      szAppName, MB_ICONERROR) ;
        // handle the error and possibly exit
          }
          else
          {
            TranslateMessage (&msg) ;
            DispatchMessage (&msg) ;
          }
    }
    return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
 
  static int result = 5;
  int iLength;
  TCHAR szBuffer[100];
  HDC        hdc ;
  PAINTSTRUCT ps ;
  RECT        rect ;
       
  switch (message)
  {
    case WM_CREATE:
     
        // Create child window .START
        hwndChild = CreateWindow(szChildClass, NULL,
                                WS_CHILDWINDOW  | WS_VSCROLL |
                                WS_CLIPSIBLINGS ,
                                40,40,360,420,
                                hwnd, (HMENU) 1001,
                                (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE),
                                NULL);
        ShowWindow (hwndChild, SW_SHOW);
          hwndChildChild = CreateWindow(szChildChildClass, NULL,
                                WS_CHILDWINDOW | WS_VISIBLE |
                                WS_CLIPSIBLINGS ,
                                0,0,20,20,
                                hwndChild, (HMENU) 1002,
                                (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE),
                                NULL); 
                   
        // Create child window .FINISH
     
      return 0 ;
         
    case WM_PAINT:
         
          hdc = BeginPaint (hwnd, &ps) ;
         
          GetClientRect (hwnd, &rect) ;
     
         
          EndPaint (hwnd, &ps) ;
          return 0 ;
    case WM_SIZE:
             
        return 0;
     
    case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
  }
    return DefWindowProc (hwnd, message, wParam, lParam) ;
}

LRESULT CALLBACK ChildWndProc (HWND hwnd, UINT message,
                                      WPARAM wParam, LPARAM lParam)
{
 
  switch(message)
  {
  case WM_CREATE:
     
      return 0;
 
  case WM_PAINT:

      return 0;
  case WM_SIZE:
     
        return 0;
  }
  return DefWindowProc(hwnd, message, wParam, lParam);
}
LRESULT CALLBACK ChildChildWndProc (HWND hwnd, UINT message,
                                      WPARAM wParam, LPARAM lParam)
{

  switch(message)
  {
  case WM_CREATE:

      return 0;
 
  case WM_PAINT:

      return 0;
  case WM_SIZE:
     
        return 0;
  }
  return DefWindowProc(hwnd, message, wParam, lParam);
}

---

in your while statment add Sleep(1);

Your process is spinning on WM_PAINT because the update region is never cleared for either of the child windows.

The WM_PAINT Message (second to last paragraph)

You can use this as your "template" WM_PAINT handler:

Code:

---

case WM_PAINT:
  ValidateRect(hwnd, 0); /* clear/validate update region */
  return 0;

---

gg

Thank you for the 2 replies, I tried the sleep( ) first, in the while statement and that stopped the cpu running at 100%. Why does this work?

Then I tried ValidateRect() in WM_PAINT. When I put ValidateRect() in both child winprocs that also worked.
Now I understand. :)

Code:

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case WM_PAINT
      return 0;  // will loop for ever

---

Thanks
phil