Detecting change of MDI child form

[Michael Culley]

Mr felis,

I tried it and it worked OK. Here is the code:

Option Explicit

Private WithEvents mForm As Form

Private Sub MDIForm_Click()
Set mForm = New Form1
mForm.Show
mForm_Deactivate
End Sub

Private Sub mForm_Deactivate()
Set mForm = ActiveForm
Me.Caption = mForm.hWnd
End Sub

Also in form1 (just for testing)

Option Explicit

Private Sub Form_Load()
Me.Caption = hWnd
End Sub

"mrfelis" <mrfelis@yahoo.NOSPAM.com> wrote in message
news:3a77305b$1@news.devx.com...
> Michael Culley <mike@vbdotcom.com> wrote in message
> news:3a76137c@news.devx.com...
> > mr felis,
> >
> > you only need to get the events of 1 form - the active one. When you get
a
> > form_deactive event just change the variable to be the new form. There
> would
> Does the MDIForm.ActiveForm property get changed before or after the child
> form_deactivate? If it is after, who would you catch the event for the
> activating form using the single variable?
>
> The object array inside a collection raising evnets could work though.
> --
> ~~~
> !ti timda I ,KO
> .em deppals nocaeB sivaM
> !draH
> ~~
> C'Ya,
> mrfelis@yahoo!com
> Michael Culley <mike@vbdotcom.com> wrote in message
> news:3a76137c@news.devx.com...
> > mr felis,
> >
> > you only need to get the events of 1 form - the active one. When you get
a
> > form_deactive event just change the variable to be the new form. There
> would
> > be some additional stuffing around when no forms were visible but it
most
> > likely would be workable.
> >
> > We use a different method. We have a usercontrol on the MDI form (we
call
> it
> > the AM control) and a control on every MDI child form (called the FM
> > control - inhouse joke). When the FM control detects that the form loses
> > focus it sends a message to the AM control which raises an event on the
> MDI
> > form. It also serves other purposes such as toolbar control, sending
> > messages between forms etc.
> >
> > >The problem lies in VB not allowing WithEvents to be used with arrays
> >
> > There are ways around this. Which boils down to creating an array of
> classes
> > that has a withevents variable in it and then having the classes call a
> > central location.
> >
> > Michael Culley
> >
> > "mrfelis" <mrfelis@yahoo.NOSPAM.com> wrote in message
> > news:3a7600ac$1@news.devx.com...
> > > Tim Coulter <tim.coulter@wanadoo.fr> wrote in message
> > > news:3a75de9c$1@news.devx.com...
> > > >
> > > > What I really want to do is raise events within child forms which
can
> be
> > > Sinking events for MDI children may prove to be very limited in use.
The
> > > problem lies in VB not allowing WithEvents to be used with arrays. So
> you
> > > will only be able Sink an Event of the activating form if you limit
the
> > > number of mdi children to that allow loaded. You'll need one variable
> for
> > > each form. Then each event would have to be coded separately. This can
> get
> > > very messy.
> > >
> > > Since VB only allows 1 MDI form per application, why not just code
> public
> > > subs inplace of event sinks?
> > >
> > > > From your explanation, I now understand that I need to intercept the
> > > WM_MDIACTIVATE
> > > > message to the MDIClient window. But can you please tell me how to
get
> a
> > >
> > > Well, you could put the code into form_Activate event for the mdi
child
> > > forms as the last line in Tom's post indicates. This should be clean
> > enough
> > > unless you have different form types to be shown as mdi children.
> > >
> > > Here's an example:
> > >
> > > 'MDI form code
> > > Option Explicit
> > >
> > > Public Sub Activated()
> > > Me.Caption = "MDI form: Child " & ActiveForm.Caption
> > > End Sub
> > >
> > >
> > > Private Sub mnuNew_Click()
> > > With New frmChild
> > > .Caption = Forms.Count
> > > .Show
> > > End With
> > > End Sub
> > >
> > > 'mdi child form code
> > > Private Sub Form_Activate()
> > > MDIForm1.Activated
> > > End Sub
> > >
> > >
> > >
> > > --
> > > ~~~
> > > !ti timda I ,KO
> > > .em deppals nocaeB sivaM
> > > !draH
> > > ~~
> > > C'Ya,
> > > mrfelis@yahoo!com
> > >
> > >
> > >
> >
> >
>
>

[Michael Culley]

Mr felis,

I tried it and it worked OK. Here is the code:

Option Explicit

Private WithEvents mForm As Form

Private Sub MDIForm_Click()
Set mForm = New Form1
mForm.Show
mForm_Deactivate
End Sub

Private Sub mForm_Deactivate()
Set mForm = ActiveForm
Me.Caption = mForm.hWnd
End Sub

Also in form1 (just for testing)

Option Explicit

Private Sub Form_Load()
Me.Caption = hWnd
End Sub

"mrfelis" <mrfelis@yahoo.NOSPAM.com> wrote in message
news:3a77305b$1@news.devx.com...
> Michael Culley <mike@vbdotcom.com> wrote in message
> news:3a76137c@news.devx.com...
> > mr felis,
> >
> > you only need to get the events of 1 form - the active one. When you get
a
> > form_deactive event just change the variable to be the new form. There
> would
> Does the MDIForm.ActiveForm property get changed before or after the child
> form_deactivate? If it is after, who would you catch the event for the
> activating form using the single variable?
>
> The object array inside a collection raising evnets could work though.
> --
> ~~~
> !ti timda I ,KO
> .em deppals nocaeB sivaM
> !draH
> ~~
> C'Ya,
> mrfelis@yahoo!com
> Michael Culley <mike@vbdotcom.com> wrote in message
> news:3a76137c@news.devx.com...
> > mr felis,
> >
> > you only need to get the events of 1 form - the active one. When you get
a
> > form_deactive event just change the variable to be the new form. There
> would
> > be some additional stuffing around when no forms were visible but it
most
> > likely would be workable.
> >
> > We use a different method. We have a usercontrol on the MDI form (we
call
> it
> > the AM control) and a control on every MDI child form (called the FM
> > control - inhouse joke). When the FM control detects that the form loses
> > focus it sends a message to the AM control which raises an event on the
> MDI
> > form. It also serves other purposes such as toolbar control, sending
> > messages between forms etc.
> >
> > >The problem lies in VB not allowing WithEvents to be used with arrays
> >
> > There are ways around this. Which boils down to creating an array of
> classes
> > that has a withevents variable in it and then having the classes call a
> > central location.
> >
> > Michael Culley
> >
> > "mrfelis" <mrfelis@yahoo.NOSPAM.com> wrote in message
> > news:3a7600ac$1@news.devx.com...
> > > Tim Coulter <tim.coulter@wanadoo.fr> wrote in message
> > > news:3a75de9c$1@news.devx.com...
> > > >
> > > > What I really want to do is raise events within child forms which
can
> be
> > > Sinking events for MDI children may prove to be very limited in use.
The
> > > problem lies in VB not allowing WithEvents to be used with arrays. So
> you
> > > will only be able Sink an Event of the activating form if you limit
the
> > > number of mdi children to that allow loaded. You'll need one variable
> for
> > > each form. Then each event would have to be coded separately. This can
> get
> > > very messy.
> > >
> > > Since VB only allows 1 MDI form per application, why not just code
> public
> > > subs inplace of event sinks?
> > >
> > > > From your explanation, I now understand that I need to intercept the
> > > WM_MDIACTIVATE
> > > > message to the MDIClient window. But can you please tell me how to
get
> a
> > >
> > > Well, you could put the code into form_Activate event for the mdi
child
> > > forms as the last line in Tom's post indicates. This should be clean
> > enough
> > > unless you have different form types to be shown as mdi children.
> > >
> > > Here's an example:
> > >
> > > 'MDI form code
> > > Option Explicit
> > >
> > > Public Sub Activated()
> > > Me.Caption = "MDI form: Child " & ActiveForm.Caption
> > > End Sub
> > >
> > >
> > > Private Sub mnuNew_Click()
> > > With New frmChild
> > > .Caption = Forms.Count
> > > .Show
> > > End With
> > > End Sub
> > >
> > > 'mdi child form code
> > > Private Sub Form_Activate()
> > > MDIForm1.Activated
> > > End Sub
> > >
> > >
> > >
> > > --
> > > ~~~
> > > !ti timda I ,KO
> > > .em deppals nocaeB sivaM
> > > !draH
> > > ~~
> > > C'Ya,
> > > mrfelis@yahoo!com
> > >
> > >
> > >
> >
> >
>
>

[Michael Culley]

Tim,

> However, from my experimentation,
> the biggest problem occurs when the last child form is closed, since the
> MDIForm has no way of knowing that the active form is Nothing.

You are right, the code I posted doesn't work too well when unloading an MDI
child form.

> Michael, your AM/FM concept sounds like a very sound approach. Is it
possible
> to get some details of the workings, or is it confidential?

I'll make up a sample project tonight.

Michael Culley

"Tim Coulter" <tim.coulter@wanadoo.fr> wrote in message
news:3a769abc$1@news.devx.com...
>
> Thanks to everyone for your suggestions. As Michael pointed out, it is
only
> necessary to sink the events for the active child form (hence the need to
> know when it changes) so it would be reasonable to get the each child form
> to notify the MDIForm when it becomes active. However, from my
experimentation,
> the biggest problem occurs when the last child form is closed, since the
> MDIForm has no way of knowing that the active form is Nothing.
>
> Tom, you were right, the WM_MDIACTIVATE message occurs before the
MDIForm.ActiveForm
> property changes, so this is not going to help.
>
> Michael, your AM/FM concept sounds like a very sound approach. Is it
possible
> to get some details of the workings, or is it confidential?
>
> Thanks again everone.
> Tim Coulter
>
>
>
> tjeshGibberish@blazenet.net (Tom Esh) wrote:
> >>...But can you please tell me how to get a
> >>hWnd for the MDIClient window?..
> >The classname is "MDIClient", so...
> >hwndClient = FindWindowEx(MDIForm.hwnd, 0&, "MDIClient", vbNullString)
> >....does it.
> >Note however the specific child being activated/deactivated is not
> >identified in the msg params received by MDIClient. (Windows just
> >tosses the message at MDIClient and expects it to figure out the
> >rest.) I'm not sure about the sequence, but the MDIForm.ActiveForm
> >prop may not get updated until WM_MDIACTIVATE has been processed.
> >
> >Truth is I've never needed the Api for this. Typically I just have the
> >child call a public or friend method in the MDI parent form, and if
> >neccessary pass a reference to itself.
> >
> >Ex:
> >'In the MDI parent...
> >Friend Sub ChildActivated(oChild As frmChild)
> > '...do whatever...
> >End Sub
> >
> >'In frmChild...
> >Private Sub Form_Activate()
> > MDIForm.ChildActivated Me
> >End Sub
> >
> >
> >On 29 Jan 2001 13:20:28 -0800, "Tim Coulter" <tim.coulter@wanadoo.fr>
> >wrote:
> >
> >>
> >>Tom,
> >>
> >>Many thanks for your response to my question. I am a little closer to
achieving
> >>my objective, but not quite there yet.
> >>
> >>What I really want to do is raise events within child forms which can be
> >>handled in the MDI parent form. To do this, the MDIForm needs to keep
track
> >>of the active child form, and so it needs an event (or equivalent) which
> >>indicates when the user switches between child forms.
> >>
> >>From your explanation, I now understand that I need to intercept the
WM_MDIACTIVATE
> >>message to the MDIClient window. But can you please tell me how to get
> a
> >>hWnd for the MDIClient window?
> >>
> >>Thanks again for your advice.
> >>Tim Coulter
> >>
> >
> >
> >-Tom
> >(please post replies to the newsgroup)
>

[Michael Culley]

Tim,

> However, from my experimentation,
> the biggest problem occurs when the last child form is closed, since the
> MDIForm has no way of knowing that the active form is Nothing.

You are right, the code I posted doesn't work too well when unloading an MDI
child form.

> Michael, your AM/FM concept sounds like a very sound approach. Is it
possible
> to get some details of the workings, or is it confidential?

I'll make up a sample project tonight.

Michael Culley

"Tim Coulter" <tim.coulter@wanadoo.fr> wrote in message
news:3a769abc$1@news.devx.com...
>
> Thanks to everyone for your suggestions. As Michael pointed out, it is
only
> necessary to sink the events for the active child form (hence the need to
> know when it changes) so it would be reasonable to get the each child form
> to notify the MDIForm when it becomes active. However, from my
experimentation,
> the biggest problem occurs when the last child form is closed, since the
> MDIForm has no way of knowing that the active form is Nothing.
>
> Tom, you were right, the WM_MDIACTIVATE message occurs before the
MDIForm.ActiveForm
> property changes, so this is not going to help.
>
> Michael, your AM/FM concept sounds like a very sound approach. Is it
possible
> to get some details of the workings, or is it confidential?
>
> Thanks again everone.
> Tim Coulter
>
>
>
> tjeshGibberish@blazenet.net (Tom Esh) wrote:
> >>...But can you please tell me how to get a
> >>hWnd for the MDIClient window?..
> >The classname is "MDIClient", so...
> >hwndClient = FindWindowEx(MDIForm.hwnd, 0&, "MDIClient", vbNullString)
> >....does it.
> >Note however the specific child being activated/deactivated is not
> >identified in the msg params received by MDIClient. (Windows just
> >tosses the message at MDIClient and expects it to figure out the
> >rest.) I'm not sure about the sequence, but the MDIForm.ActiveForm
> >prop may not get updated until WM_MDIACTIVATE has been processed.
> >
> >Truth is I've never needed the Api for this. Typically I just have the
> >child call a public or friend method in the MDI parent form, and if
> >neccessary pass a reference to itself.
> >
> >Ex:
> >'In the MDI parent...
> >Friend Sub ChildActivated(oChild As frmChild)
> > '...do whatever...
> >End Sub
> >
> >'In frmChild...
> >Private Sub Form_Activate()
> > MDIForm.ChildActivated Me
> >End Sub
> >
> >
> >On 29 Jan 2001 13:20:28 -0800, "Tim Coulter" <tim.coulter@wanadoo.fr>
> >wrote:
> >
> >>
> >>Tom,
> >>
> >>Many thanks for your response to my question. I am a little closer to
achieving
> >>my objective, but not quite there yet.
> >>
> >>What I really want to do is raise events within child forms which can be
> >>handled in the MDI parent form. To do this, the MDIForm needs to keep
track
> >>of the active child form, and so it needs an event (or equivalent) which
> >>indicates when the user switches between child forms.
> >>
> >>From your explanation, I now understand that I need to intercept the
WM_MDIACTIVATE
> >>message to the MDIClient window. But can you please tell me how to get
> a
> >>hWnd for the MDIClient window?
> >>
> >>Thanks again for your advice.
> >>Tim Coulter
> >>
> >
> >
> >-Tom
> >(please post replies to the newsgroup)
>

[Michael Culley]

This is available if anyone is interested then email me.

--
Michael Culley

www.vbdotcom.com
"Michael Culley" <mike@vbdotcom.com> wrote in message
news:3a7775b4@news.devx.com...
> Tim,
>
> > However, from my experimentation,
> > the biggest problem occurs when the last child form is closed, since the
> > MDIForm has no way of knowing that the active form is Nothing.
>
> You are right, the code I posted doesn't work too well when unloading an
MDI
> child form.
>
> > Michael, your AM/FM concept sounds like a very sound approach. Is it
> possible
> > to get some details of the workings, or is it confidential?
>
> I'll make up a sample project tonight.
>
> Michael Culley
>
> "Tim Coulter" <tim.coulter@wanadoo.fr> wrote in message
> news:3a769abc$1@news.devx.com...
> >
> > Thanks to everyone for your suggestions. As Michael pointed out, it is
> only
> > necessary to sink the events for the active child form (hence the need
to
> > know when it changes) so it would be reasonable to get the each child
form
> > to notify the MDIForm when it becomes active. However, from my
> experimentation,
> > the biggest problem occurs when the last child form is closed, since the
> > MDIForm has no way of knowing that the active form is Nothing.
> >
> > Tom, you were right, the WM_MDIACTIVATE message occurs before the
> MDIForm.ActiveForm
> > property changes, so this is not going to help.
> >
> > Michael, your AM/FM concept sounds like a very sound approach. Is it
> possible
> > to get some details of the workings, or is it confidential?
> >
> > Thanks again everone.
> > Tim Coulter
> >
> >
> >
> > tjeshGibberish@blazenet.net (Tom Esh) wrote:
> > >>...But can you please tell me how to get a
> > >>hWnd for the MDIClient window?..
> > >The classname is "MDIClient", so...
> > >hwndClient = FindWindowEx(MDIForm.hwnd, 0&, "MDIClient", vbNullString)
> > >....does it.
> > >Note however the specific child being activated/deactivated is not
> > >identified in the msg params received by MDIClient. (Windows just
> > >tosses the message at MDIClient and expects it to figure out the
> > >rest.) I'm not sure about the sequence, but the MDIForm.ActiveForm
> > >prop may not get updated until WM_MDIACTIVATE has been processed.
> > >
> > >Truth is I've never needed the Api for this. Typically I just have the
> > >child call a public or friend method in the MDI parent form, and if
> > >neccessary pass a reference to itself.
> > >
> > >Ex:
> > >'In the MDI parent...
> > >Friend Sub ChildActivated(oChild As frmChild)
> > > '...do whatever...
> > >End Sub
> > >
> > >'In frmChild...
> > >Private Sub Form_Activate()
> > > MDIForm.ChildActivated Me
> > >End Sub
> > >
> > >
> > >On 29 Jan 2001 13:20:28 -0800, "Tim Coulter" <tim.coulter@wanadoo.fr>
> > >wrote:
> > >
> > >>
> > >>Tom,
> > >>
> > >>Many thanks for your response to my question. I am a little closer to
> achieving
> > >>my objective, but not quite there yet.
> > >>
> > >>What I really want to do is raise events within child forms which can
be
> > >>handled in the MDI parent form. To do this, the MDIForm needs to keep
> track
> > >>of the active child form, and so it needs an event (or equivalent)
which
> > >>indicates when the user switches between child forms.
> > >>
> > >>From your explanation, I now understand that I need to intercept the
> WM_MDIACTIVATE
> > >>message to the MDIClient window. But can you please tell me how to get
> > a
> > >>hWnd for the MDIClient window?
> > >>
> > >>Thanks again for your advice.
> > >>Tim Coulter
> > >>
> > >
> > >
> > >-Tom
> > >(please post replies to the newsgroup)
> >
>
>

[Michael Culley]

This is available if anyone is interested then email me.

--
Michael Culley

www.vbdotcom.com
"Michael Culley" <mike@vbdotcom.com> wrote in message
news:3a7775b4@news.devx.com...
> Tim,
>
> > However, from my experimentation,
> > the biggest problem occurs when the last child form is closed, since the
> > MDIForm has no way of knowing that the active form is Nothing.
>
> You are right, the code I posted doesn't work too well when unloading an
MDI
> child form.
>
> > Michael, your AM/FM concept sounds like a very sound approach. Is it
> possible
> > to get some details of the workings, or is it confidential?
>
> I'll make up a sample project tonight.
>
> Michael Culley
>
> "Tim Coulter" <tim.coulter@wanadoo.fr> wrote in message
> news:3a769abc$1@news.devx.com...
> >
> > Thanks to everyone for your suggestions. As Michael pointed out, it is
> only
> > necessary to sink the events for the active child form (hence the need
to
> > know when it changes) so it would be reasonable to get the each child
form
> > to notify the MDIForm when it becomes active. However, from my
> experimentation,
> > the biggest problem occurs when the last child form is closed, since the
> > MDIForm has no way of knowing that the active form is Nothing.
> >
> > Tom, you were right, the WM_MDIACTIVATE message occurs before the
> MDIForm.ActiveForm
> > property changes, so this is not going to help.
> >
> > Michael, your AM/FM concept sounds like a very sound approach. Is it
> possible
> > to get some details of the workings, or is it confidential?
> >
> > Thanks again everone.
> > Tim Coulter
> >
> >
> >
> > tjeshGibberish@blazenet.net (Tom Esh) wrote:
> > >>...But can you please tell me how to get a
> > >>hWnd for the MDIClient window?..
> > >The classname is "MDIClient", so...
> > >hwndClient = FindWindowEx(MDIForm.hwnd, 0&, "MDIClient", vbNullString)
> > >....does it.
> > >Note however the specific child being activated/deactivated is not
> > >identified in the msg params received by MDIClient. (Windows just
> > >tosses the message at MDIClient and expects it to figure out the
> > >rest.) I'm not sure about the sequence, but the MDIForm.ActiveForm
> > >prop may not get updated until WM_MDIACTIVATE has been processed.
> > >
> > >Truth is I've never needed the Api for this. Typically I just have the
> > >child call a public or friend method in the MDI parent form, and if
> > >neccessary pass a reference to itself.
> > >
> > >Ex:
> > >'In the MDI parent...
> > >Friend Sub ChildActivated(oChild As frmChild)
> > > '...do whatever...
> > >End Sub
> > >
> > >'In frmChild...
> > >Private Sub Form_Activate()
> > > MDIForm.ChildActivated Me
> > >End Sub
> > >
> > >
> > >On 29 Jan 2001 13:20:28 -0800, "Tim Coulter" <tim.coulter@wanadoo.fr>
> > >wrote:
> > >
> > >>
> > >>Tom,
> > >>
> > >>Many thanks for your response to my question. I am a little closer to
> achieving
> > >>my objective, but not quite there yet.
> > >>
> > >>What I really want to do is raise events within child forms which can
be
> > >>handled in the MDI parent form. To do this, the MDIForm needs to keep
> track
> > >>of the active child form, and so it needs an event (or equivalent)
which
> > >>indicates when the user switches between child forms.
> > >>
> > >>From your explanation, I now understand that I need to intercept the
> WM_MDIACTIVATE
> > >>message to the MDIClient window. But can you please tell me how to get
> > a
> > >>hWnd for the MDIClient window?
> > >>
> > >>Thanks again for your advice.
> > >>Tim Coulter
> > >>
> > >
> > >
> > >-Tom
> > >(please post replies to the newsgroup)
> >
>
>