Introduction to STRICT and Message Crackers

• Microsoft Windows Software Development Kit (SDK) 3.1

SUMMARY

The WINDOWS.H and WINDOWSX.H header files in version 3.1 of the Microsoft Windows Software Development Kit (SDK) provide new features to make developing applications for the Windows environment faster and easier. These features enable the C compiler to find many common programming errors at compile time.

This article provides an overview and examples of the new features, as well as a road map to other resources in the SDK that explain them.

MORE INFORMATION

The WINDOWS.H and WINDOWSX.H header files provide the following features:

• New data types and their associated definitions



• A preprocessor variable, STRICT, which enforces the strictest possible type checking by the compiler



• Macros to simplify many common operations in Windows programming



• Control macros to simplify communication with Windows controls



• Message crackers (which are a convenient, portable, and type-safe method to handle messages) and their associated parameters and return values in the Windows environment

• WINDOWS.TXT, which explains the new types and STRICT features provided by WINDOWS.H.



• WINDOWSX.TXT, which explains the macros, control macros, and message crackers provided by WINDOWSX.H.



• MAKEAPP sample application, which uses all the new features of WINDOWS.H and WINDOWSX.H. MAKEAPP can create application templates that use all the new features.



• MAKEAPP.TXT, which explains how to use MAKEAPP as an application template generator.

• Make the source code for an application easier to read



• Enable the C compiler to catch programming errors



• Ease porting to 32-bit Windows

New Data Types, Type Definitions, and Helper Macros

STRICT Preprocessor Variable

   #define STRICT
   #include windows.h 

An Example of Using STRICT

   int WINAPI ReleaseDC(HWND, HDC); 

   ReleaseDC(hDC, hWnd); 

Converting Existing Code to STRICT

Macros

   lpfnOldWndProc = SetWindowLong(hwnd, GWL_WNDPROC,
                                  (LPARAM)(WNDPROC)lpfnNewWndProc); 

   lpfnOldWndProc = SubclassWindow(hwnd, lpfnNewWndProc); 

Control Message Macros

A Control Message Macro Example

   void PrintLines(HWND hwndEdit)
   {
      int line;
      int lineLast = (int)SendMessage(hwndEdit, EM_GETLINECOUNT,
                                      0, 0L);

      for (line = 0; line < lineLast; line)
      {
         int cch;
         char ach[80];

         *((LPINT)ach) = sizeof(ach);
         cch = (int)SendMessage(hwndEdit, EM_GETLINE,
                                line, (LONG)(LPSTR)ach);

         printf(ach); // or whatever ...
      }
   } 

   void PrintLines(HWND hwndEdit)
   {
      int line;
      int lineLast = Edit_GetLineCount(hwndEdit);

      for (line = 0; line < lineLast; line++)
      {
         int cch;
         char ach[80];

         cch = Edit_GetLine(hwndEdit, line, ach, sizeof(ach));

         printf(ach); // or whatever ...
      }
   } 

Message Crackers

• Data type safety, because the message crackers perform a great deal of type casting



• Simplified porting to 32-bit Windows

A Simple Message Cracker Example

   LRESULT _export CALLBACK Template_WndProc(HWND hwnd, WORD msg,
                                             WPARAM wParam,
                                             LPARAM lParam)
   {
      switch (msg)
      {
      case WM_MOUSEMOVE:
         return HANDLE_WM_MOUSEMOVE(hwnd, wParam, lParam,
                                    Template_OnMouseMove);

      case WM_LBUTTONDOWN:
         return HANDLE_WM_LBUTTONDOWN(hwnd, wParam, lParam,
                                      Template_OnLButtonDown);

      case WM_LBUTTONUP:
         return HANDLE_WM_LBUTTONDUP(hwnd, wParam, lParam,
                                     Template_OnLButtonUp);

      case WM_CTLCOLOR:
         return HANDLE_WM_CTLCOLOR(hwnd, wParam, lParam,
                                   Template_OnCtlColor);

      default:
         return Template_DefProc(hwnd, msg, wParam, lParam);
      }
   } 

   void Template_OnMouseMove(HWND hwnd, int x, int y, UINT keyFlags)
   {
      // code to handle WM_MOUSEMOVE...
   }

   void Template_OnLButtonDown(HWND hwnd, BOOL fDoubleClick, int x,
                               int y, UINT keyFlags)
   {
      // code to handle WM_LBUTTONDOWN...
   }

   void Template_OnLButtonUp(HWND hwnd, int x, int y, UINT keyFlags)
   {
      // code to handle WM_LBUTTONUP
   }

   HBRUSH Template_OnCtlColor(HWND hwnd, HDC hdc, HWND hwndChild,
                              int type)
   {
      // code to handle WM_CTLCOLOR
   } 

   LRESULT _export CALLBACK Template_WndProc(HWND hwnd, WORD msg,
                                             WPARAM wParam,
                                             LPARAM lParam)
   {
       switch (msg)
       {
       HANDLE_MSG(hwnd, WM_MOUSEMOVE, Template_OnMouseMove);
       HANDLE_MSG(hwnd, WM_LBUTTONDOWN, Template_OnLButtonDown);
       HANDLE_MSG(hwnd, WM_LBUTTONDBLCLK, Template_OnLButtonDown);
       HANDLE_MSG(hwnd, WM_LBUTTONUP, Template_OnLButtonUp);

       default:
           return Template_DefProc(hwnd, msg, wParam, lParam);
       }
   } 

Message Cracker Basics

1. Splits wParam and lParam into component parts



2. Type casts the parts correctly



3. Passes the values as parameters to the application-supplied function (in this case, the Template_OnMouseMove function)



4. Returns an appropriate value from processing the message

Message Crackers Have Many Uses

• Passing messages to DefWindowProc, CallWindowProc, and so forth.



• Private and registered window messages.



• Windows with instance data.



• Dialog box procedures.



• Window subclassing.



• Another way to create dialog box procedures that allows a dialog box procedure to return an LRESULT data type. This method allows an application to bypass the traditional limitation that dialog box procedures must return a BOOL data type.

Additional query words: no32bit 3.10

Keywords : kb16bitonly
Version : WINDOWS:3.1
Platform : WINDOWS
Issue type :