Intercepting Child Window messages

[Charles Pegge]

I found this technique very useful for sending notifications to the main window. Function keys and control /escape/return keys are intercepted in the message loop before they reach child windows.

Code: OxygenBasic

1.  
2.   'MESSAGE LOOP
3.  '============
4.  '
5.  sys bRet
6.   '
7.  do while bRet := GetMessage (&wm, 0, 0, 0)
8.     if bRet == -1 then
9.       'show an error message?
10.    else
11.       if wm.message=WM_KEYDOWN
12.         m=wm.wparam
13.         select case m
14.         case VK_RETURN
15.           for i=1 to nchw
16.             if wm.hwnd=hchw(i)
17.               SendMessage hwnd,WM_COMMAND,2000+VK_RETURN,0
18.               if i>1 then continue while 'first window is editor
19.            end if
20.           next
21.         case VK_ESCAPE
22.           'SendMessage hwnd,WM_CLOSE,0,0
23.        case VK_F1 to VK_F10
24.           SendMessage hwnd,WM_COMMAND,1001+m-VK_F1, 0
25.         case "A" to "Z"
26.           if CtrlKey then
27.             SendMessage hwnd,WM_COMMAND,2000+m, 0
28.             if m=65 or m=70 or m=71 then continue while
29.           end if
30.         end select
31.       end if
32.       TranslateMessage @wm
33.       DispatchMessage @wm
34.     end if
35.   wend
36.   '
37.  function=wm.wparam
38.  
39.   end function ; end of WinMain
40.  

On the receiving end, WM_COMMAND messages are captured. The originating child window can be identified by GetFocus. (it may be the built-in Find Box or Goto Box here)

Code: OxygenBasic

1.   case WM_COMMAND
2.     sys id,co,hw,a,b
3.     id=wparam and 0xffff
4.     co=wparam >>16
5.     hw=hchw[0]
6.     select case id
7.     case 1001 'F1
8.      SetWindowText hWnd, "Help"
9.       s=GetText hw
10.       HelpMessageBox
11.     case 1003 'F3
12.      FindKeyword hchw, 0
13.       SetWindowText hWnd, "Find Next"
14.     case 1004 'F4
15.      FindKeyword hchw, 1
16.       SetWindowText hWnd, "Find Next Word"
17.     case 1005 'F5
18.      SetWindowText hWnd, "Compile"
19.       s=GetText hw
20.       Exec s
21.     case 1008 'F8
22.      string f
23.       SetWindowText hWnd, "Load File"
24.       f=GetFileName fi,0
25.       if f then
26.         fi=f
27.         s=GetFile fi
28.         le=len s
29.         SendMessage hchw[0],WM_SETTEXT,le,strptr s
30.       end if
31.       SetWindowText hwnd,strptr fi
32.     case 1009 'F9
33.      string f
34.       if fo="" then fo="_.o2bas"
35.       f=fo
36.       if GetAsyncKeyState VK_SHIFT
37.         f=GetFileName fo,1
38.       end if
39.       if f then
40.         fo=f
41.         s=GetText hchw[0]
42.         putfile fo,s
43.         SetWindowText hWnd, "Saved "+fo
44.       end if
45.     case 2065 'Ctrl A
46.      SelectAll hw
47.     case 2070 'Ctrl F
48.      SelectAll hchw(1)
49.     case 2071 'Ctrl G
50.      SendMessage hw,EM_GETSEL,@a,@b
51.       a=SendMessage hw,EM_LINEFROMCHAR,a,0
52.       string sl=str(a+1)
53.       SendMessage hchw(2),WM_SETTEXT,len(sl),strptr sl
54.       SelectAll hchw(2)
55.     case 2013 'VK_ENTER
56.      sys v,w,h=GetFocus()
57.       if h=hchw(1)
58.         FindKeyWord hchw,0
59.       elseif h=hchw(2)
60.         string g=nuls 24
61.         SendMessage h,WM_GETTEXT,24,strptr g
62.         v=val g
63.         if v then
64.           v=SendMessage hw,EM_LINEINDEX,v-1,0
65.           SetFocus hw
66.           SendMessage hw,EM_SETSEL,v,v
67.           SendMessage hw,EM_SCROLLCARET,0,0
68.         end if
69.       end if
70.     end select
71.  

Charles