C / C++ / MFC

Todd Smith

BOOL RetrievePixels(HDC hDC,HBITMAP hBitmap,
                    LPBYTE *ppBytes,
                    LPBITMAPINFO lpBmi)
{
  BITMAPINFO bmi={{sizeof(BITMAPINFOHEADER),0,0,1,0,0,0,0,0,0,0}};
  memcpy(lpBmi,&bmi,sizeof(bmi));

  if(GetDIBits(hDC,hBitmap,0,0,NULL,lpBmi,DIB_RGB_COLORS)==0){
    return FALSE;
  }

  if((*ppBytes=(LPBYTE)malloc(
        4*((lpBmi->bmiHeader.biWidth*3+3)/4)*lpBmi->bmiHeader.biHeight))==NULL){
    return FALSE;
  }

  lpBmi->bmiHeader.biBitCount=24;
  lpBmi->bmiHeader.biCompression=BI_RGB;

  if(GetDIBits(hDC,hBitmap,0,lpBmi->bmiHeader.biHeight,*ppBytes,lpBmi,DIB_RGB_COLORS)==0){
    return FALSE;
  }

  return TRUE;
}

OnKickIdle(...)
{
  UpdateDialogControls ( this, FALSE );
}

1. First, reserve some range of user defined message identifiers, say WM_FIRST_TREECOMMAND, WM_FIRST_TREECOMMAND+1, ... , WM_FIRST_TREECOMMAND+max_commands-1, where max_commands is large enough so that the range holds room for all the commands on your command tree. This decision you have to made it on compile time, so allow for a reasonably large range.
   
2. Have all the range of message IDs mapped to the same message handler (say OnTreeComand) by means of the MFC ON_COMMAND_RANGE.
   
3. Define a map (use std::map, for instance, or your favorite map container) that translates message IDs to TreeCommand objects (or whatever your command objects are named).
   
4. On initialization time, build a CMenu object that mimicks the structure of your command tree, by recursively transversing the tree. The key member function to call is CMenu::AppendMenu() that serves both for inserting commands and submenus. Use the range of user defined message IDs for assigning identifiers. For each new command inserted into the menu add an entry to the map of the form treecommand_map[id_command]=command, where command is the appropriate TreeCommand object (or a reference to it, or a pointer, you are the designer).
   
5. That's it, now your message handler OnTreeCommand only has to retrieve the TreeCommand object from the identifier passed using treecommand_map and execute it:
   

void CYourWnd::OnTreeCommand(UINT nID){
 treecommand_map[nID].Execute();
}