[Oberon] FPGA - DIY Dialogs

Tomas Kral thomas.kral at email.cz
Sat Dec 15 11:31:42 CET 2018

On Thu, 13 Dec 2018 22:13:43 +0100
Tomas Kral <thomas.kral at email.cz> wrote:

> Fun when I try to add some message loop (handler), as I do not
> understand this part much.

I have copied over `Handler' code from `GraphicFrames.Mod', and skinned it to a bare skeleton. It seems
that to tap into Oberon event loop, one needs to extend `DisplayFrame' and install own `Handle'.

It seems to avoid circular references, there is a need of three modules, Main, Control, and Frame.
Possibly the concept of MVC, as noted in OOP by H.P.Mossenbock.

I am now able to clear frame, on opening and resizing, plus calling Update to draw DLog elements.
How do I clear frame only on initial opening not closing or resizing?
Note actual M.Y, M.H, has to be picked from the frame message! I do not get(*understand*) all the
other events, except `Oberon.InputMsg'. What if, I needed to add a new
handler for each `DLog' element at runtime, how do I chain all handlers then?

  Frame* = POINTER TO FrameDesc;
  FrameDesc* = RECORD (Display.FrameDesc)
  END ;

  UpdateMsg = RECORD (Display.FrameMsg)
    id: INTEGER;
  END ;

  PROCEDURE Handle*(F: Display.Frame; VAR M: Display.FrameMsg);
    VAR x, y, h: INTEGER;
    CASE F OF Frame:
      CASE M OF
          IF M.id = Oberon.track THEN
            x := M.X; y := M.Y;
            IF M.keys # {} THEN ELSE Oberon.DrawMouse(MyMouse, x, y) END
          ELSIF M.id = Oberon.consume THEN
       | UpdateMsg: (*my update, not sure what to do here*)
       | Oberon.ControlMsg:
           IF M.id = Oberon.neutralize THEN Oberon.RemoveMarks(F.X, F.Y, F.W, F.H);
             Out.String("neutralize msg"); Out.Ln
           ELSIF M.id = Oberon.defocus THEN END
       | Oberon.SelectionMsg: Out.String("select msg"); Out.Ln
       | Oberon.CopyMsg: Oberon.RemoveMarks(F.X, F.Y, F.W, F.H);
       | MenuViewers.ModifyMsg:
           Out.String("modify msg"); Out.Ln; 
           Display.ReplConst(Display.black, F.X, M.Y, F.W, M.H, Display.replace); (*clear frame*)
           DLogs.Update (*redrawing dialog screen*)
  END Handle;

Tomas Kral <thomas.kral at email.cz>

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