[lazarus] How to scroll TMemo control in code

[Mattias Gaertner]

On Fri, 28 Mar 2003 00:32:12 +0100
Marc Weustink <marc at dommelstein.net> wrote:

> At 07:02 28-3-2003 +0800, you wrote:
> >Can anybody try help me figure out how to scroll the TMemo
> >programatically?
> >
> >I have seen this code in Delphi, though I am not sure if it works (in
> >Delphi)
> >
> >procedure MemoScrollDown(Memo: TMemo);
> >var
> >  ScrollMessage:TWMVScroll; (I replace this one with TLMVScroll)
> >  i:integer;
> >begin
> >  ScrollMessage.Msg:=WM_VScroll; (this one with LM_VScroll)
> >  for i := 0 to Memo.Lines.Count do
> >  begin
> >      ScrollMessage.ScrollCode:=sb_LineDown;
> >      ScrollMessage.Pos:=0;
> >   Memo.Dispatch(ScrollMessage);
> >  end;
> >end;
> >
> >
> >If I try the above code, it does not do anything.
> 
> :-)
> 
> It might work in Delphi, but it doesn't in the LCL (and never will)
> 
> Some background info:
> 
> The widgetset of you choice (GTK, win32, QT, GNOME) may be message based
> or event based or whatever to signal when the user does something. The 
> interface object of the LCL translates this to LCL-Messages (and object 
> calls) to be a bit Delphi compatible so that Delphi code based on messages
> 
> would work (code for WM_LBUTTONDOWN etc). This is thus from userinterface 
> to code.
> However the otherway around, the LCL doesn't translate messages from code 
> to the user interface.

Right.
I think, we should add some properties to TCustomMemo to control the
scrollbars.
Other components need them too, so we should do that in an independent way.
Ideas?


Mattias