Subclassing problem... CROSS

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  • WhiteRavenEye
    #1

    Subclassing problem... CROSS

    Why can't I subclass any window except mine in VB?
    Do I have to write dll for this?
    I've tried to subclass it with SetWindowLong but without success...

    Does anyone know how to subclass window ANY window in VB?

    Thanks...

    Tags: None
    • Frank Adam
      #2
      Re: Subclassing problem... CROSS

      On Sat, 23 Aug 2003 22:16:30 +0200, WhiteRavenEye
      <whiteraveneye@ hotmail.com> wrote:
      [color=blue]
      >Why can't I subclass any window except mine in VB?
      >Do I have to write dll for this?
      >I've tried to subclass it with SetWindowLong but without success...
      >
      >Does anyone know how to subclass window ANY window in VB?
      >[/color]
      SetWindowsHookE x, but you'll have to have it in a real DLL.

      --

      Regards, Frank

        Comment

        • Asperamanca
          #3
          Re: Subclassing problem... CROSS

          fajp@xxxxoptush ome.com.au (Frank Adam) wrote in message news:<3f47dbca. 101243249@news-vip.optusnet.co m.au>...[color=blue]
          > On Sat, 23 Aug 2003 22:16:30 +0200, WhiteRavenEye
          > <whiteraveneye@ hotmail.com> wrote:
          >[color=green]
          > >Why can't I subclass any window except mine in VB?
          > >Do I have to write dll for this?
          > >I've tried to subclass it with SetWindowLong but without success...
          > >
          > >Does anyone know how to subclass window ANY window in VB?
          > >[/color]
          > SetWindowsHookE x, but you'll have to have it in a real DLL.[/color]

          That is not subclassing, that is window hooking (which has similar
          effects, but essentially copies the window message, unlike subclassing
          where it's your job to forward the message back to the original
          procedure).

          So why doesn't it work with SetWindowLong? Form MSDN: "GWL_WNDPRO C:
          [...] You cannot change this attribute if the window does not belong
          to the same process as the calling thread."
          So you cannot subclass windows of other processes.
          Seems like window hooking may be your only way to go.

          Robert

            Comment

            • WhiteRavenEye
              #4
              Re: Subclassing problem... CROSS

              Asperamanca wrote:[color=blue]
              > fajp@xxxxoptush ome.com.au (Frank Adam) wrote in message news:<3f47dbca. 101243249@news-vip.optusnet.co m.au>...
              >[color=green]
              >>On Sat, 23 Aug 2003 22:16:30 +0200, WhiteRavenEye
              >><whiteraveney e@hotmail.com> wrote:
              >>
              >>[color=darkred]
              >>>Why can't I subclass any window except mine in VB?
              >>>Do I have to write dll for this?
              >>>I've tried to subclass it with SetWindowLong but without success...
              >>>
              >>>Does anyone know how to subclass window ANY window in VB?
              >>>[/color]
              >>
              >>SetWindowsHoo kEx, but you'll have to have it in a real DLL.[/color]
              >
              >
              > That is not subclassing, that is window hooking (which has similar
              > effects, but essentially copies the window message, unlike subclassing
              > where it's your job to forward the message back to the original
              > procedure).
              >
              > So why doesn't it work with SetWindowLong? Form MSDN: "GWL_WNDPRO C:
              > [...] You cannot change this attribute if the window does not belong
              > to the same process as the calling thread."
              > So you cannot subclass windows of other processes.
              > Seems like window hooking may be your only way to go.
              >
              > Robert[/color]

              I must have missed that part of MSDN...
              Looks like I'll have to write dll in Delphi...
              Too bad it can't be written in VB... Damn ActiveX DLL...
              Anyway thanks...

              By WhiteRavenEye

                Comment

                • J French
                  #5
                  Re: Subclassing problem... CROSS

                  On Mon, 25 Aug 2003 12:00:12 +0200, WhiteRavenEye
                  <whiteraveneye@ hotmail.com> wrote:
                  <snip>[color=blue]
                  >
                  >I must have missed that part of MSDN...
                  >Looks like I'll have to write dll in Delphi...
                  >Too bad it can't be written in VB... Damn ActiveX DLL...
                  >Anyway thanks...[/color]

                  I may be wrong, but I believe that the SetWindowsHookE x is mainly
                  about 'snooping' - not really subclassing

                  <snip>
                  Chaining to the next hook procedure (that is, calling the
                  CallNextHookEx function) is optional. An application or library can
                  call the next hook procedure either before or after any processing in
                  its own hook procedure. Although chaining to the next hook is
                  optional, it is highly recommended; otherwise, the other applications
                  that have installed hooks will not receive hook notifications and may
                  behave incorrectly as a result
                  </snip>

                  However the Help Files are a bit unclear on all this

                    Comment

                    • Frank Adam
                      #6
                      Re: Subclassing problem... CROSS

                      On 25 Aug 2003 00:20:31 -0700, asperamanca@yah oo.com (Asperamanca)
                      wrote:
                      [color=blue]
                      >fajp@xxxxoptus home.com.au (Frank Adam) wrote in message news:<3f47dbca. 101243249@news-vip.optusnet.co m.au>...[color=green]
                      >> On Sat, 23 Aug 2003 22:16:30 +0200, WhiteRavenEye
                      >> <whiteraveneye@ hotmail.com> wrote:
                      >>[color=darkred]
                      >> >Why can't I subclass any window except mine in VB?
                      >> >Do I have to write dll for this?
                      >> >I've tried to subclass it with SetWindowLong but without success...
                      >> >
                      >> >Does anyone know how to subclass window ANY window in VB?
                      >> >[/color]
                      >> SetWindowsHookE x, but you'll have to have it in a real DLL.[/color]
                      >
                      >That is not subclassing, that is window hooking (which has similar
                      >effects, but essentially copies the window message, unlike subclassing
                      >where it's your job to forward the message back to the original
                      >procedure).
                      >[/color]
                      So CallNextHookEx is just for kicks ?
                      SetwindowsHook installs a hook at the start of the chain, a subclass
                      replaces the procedure's address with an address of it's own handler.
                      IOW, it chains 'in', instead of in front. The difference is minimal up
                      to that point.
                      When it comes to handling and changing the messages it gets a litlle
                      trickier using the hook.. Blocking is easy enough.
                      [color=blue]
                      >So you cannot subclass windows of other processes.
                      >Seems like window hooking may be your only way to go.
                      >[/color]
                      Hm.. if only i would have thought of that.. ;-p

                      --

                      Regards, Frank

                        Comment

                        • Asperamanca
                          #7
                          Re: Subclassing problem... CROSS

                          > SetwindowsHook installs a hook at the start of the chain, a subclass[color=blue]
                          > replaces the procedure's address with an address of it's own handler.
                          > IOW, it chains 'in', instead of in front. The difference is minimal up
                          > to that point.
                          > When it comes to handling and changing the messages it gets a litlle
                          > trickier using the hook.. Blocking is easy enough.[/color]

                          There are some serious differences in performance and stability.
                          Subclassing is somewhat faster than hooking (in my experience), and
                          some types of hooks are explicitly labeled "for debugging purposes
                          only" (but not the kind we're talking about). On the other hand, there
                          are things you can do with a hook that you cannot do with subclassing
                          (as we found out), also things like monitoring all keyboard / mouse
                          events.

                          Robert

                            Comment

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