keeping MDI Child forms within Main form

Dirk Naudts

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Oct 21, 2001, 7:35:50 AM10/21/01

to

Hi,

I'm looking for a way to "block" MDI-Children to move beyond the main-forms'
borders.
The main form is shown full screen, and shouldn't show scrollbars.
Childforms can be moved by the user, but not leave the screen borders.

How can I accomplish this ?

Thanks,

Dirk Naudts.

Johnnie

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Oct 21, 2001, 10:58:43 AM10/21/01

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>Hi,
>
>I'm looking for a way to "block" MDI-Children to move beyond the
>main-forms' borders.

You can catch the WM_Move message and do what ever you want with it

here is a small sample that will try to prevent a form from moving outisde
the screen it is not working correctly as you will see but I have
no time to make it work correctly right now. It will start you of though.

Regards
Johnnie.

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;

type
TForm1 = class(TForm)
private
{ Private declarations }
procedure WMMove(var Message: TWMMove); message WM_MOVE;
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.DFM}

Procedure Tform1.WMMove(Var MEssage:TWMMove);
Var
Exc: Boolean;
begin
If (message.XPos + Width) > Screen.Width then begin
left := screen.Width - width;
exc := true
end;
if (Message.YPos + height) > Screen.Height then
begin
top :=screen.Height - Height;
exc:=true;
end;
if exc then Message.Result:=0;
end;

end.

Peter Below (TeamB)

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Oct 21, 2001, 1:12:08 PM10/21/01

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In article <3bd2b3cf_1@dnews>, Dirk Naudts wrote:
> I'm looking for a way to "block" MDI-Children to move beyond the main-forms'
> borders.
> The main form is shown full screen, and shouldn't show scrollbars.
> Childforms can be moved by the user, but not leave the screen borders.
>

Limit a child form to the parents clientwindow

> Is it possible to limit the MDI client form movement, so that the form
> cannot be moved outside the client area of the MDI form?

Yes, you can handle the WM_WINDOWPOSCHANGING message in the child forms and
modify the message parameters if needs be to keep the child fully visible.
Of course this is a breach of the standard Windows behaviour.

private // in form declaration
Procedure WMWINDOWPOSCHANGING(Var msg: TWMWINDOWPOSCHANGING);
message WM_WINDOWPOSCHANGING;

Procedure TForm1.WMWINDOWPOSCHANGING(Var msg: TWMWINDOWPOSCHANGING);
var
r: TRect;
Begin
With msg.Windowpos^ Do Begin
If (flags and SWP_NOMOVE) = 0 Then Begin
Windows.GetClientrect( Application.Mainform.clienthandle, r );
If x < 0 then x:= 0;
if y < 0 then y:= 0;
if (x+cx) > r.right then x:= r.right - cx;
if (y+cy) > r.bottom then
y:= r.bottom - cy;
End;
End;
inherited;
End;

Peter Below (TeamB) 10011...@compuserve.com)
No e-mail responses, please, unless explicitly requested!
Note: I'm unable to visit the newsgroups every day at the moment,
so be patient if you don't get a reply immediately.

Dirk Naudts

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Oct 22, 2001, 3:50:21 AM10/22/01

to

Thanks Peter,

works lovely !
I used to do it this way :

procedure Tfrmnextlots.WndProc(var Message: Tmessage);
begin
// frmstrKlok is main MDI form
inherited;
if message.Msg = WM_MOVE then
begin
if left < 0 then
left := 0;
if Top < 0 then
Top := 0;
if left > (frmstrKlok.clientwidth - (width+5)) then
left := frmstrKlok.clientwidth - (width+5);
if top > frmstrKlok.clientheight - (height+60) then
top := frmstrKlok.clientheight - (height+60);
if Sys.autoupdateFormsettings then
Savepos;
end;
end;

But this produced flickering and for a (to me) unknown reason produces AV
from time to time.

But as said, your solution is MUCH better !
Peter Below (TeamB) <10011...@compuXXserve.com> schreef in berichtnieuws
VA.00007bb...@antispam.compuserve.com...