[Extgraph-developer] TSimplegraph.DrawObjectOrder

[Marco W. <in...@ca...>]

Hi guys,

My first real need and adjustment to the code is the being able to 
influence the drawing order of the GraphObjects. For this to work I've 
done the following:

    * Introduced a new TDrawObjectOrder enumeration (ooZOrder,
      ooLinksFirst, ooNodesFirst)
    * Added a published property DrawObjectOrder (default value
      ooLinksFirst for backward compatible behaviour)
    * Rewritten the TSimpleGraph.Draw method a little.

Below is a small snippet to show you how this influences the drawing of 
GraphObjects, you can compare it to the existing code in this method 
which always draws links first and the other objects on top of that. 
However this ignores the ZOrder and the need for it to happen the other 
way around (as it does in my case).

Hope to write about more changes I've made and add even more usable 
changes soon...

Regards,
Marco.

procedure TSimpleGraph.Draw(Canvas: TCanvas);
var
  I: Integer;

  (* MW *)
  procedure DrawObjects(aType: TDrawObjects);
  var
    i: integer;
  begin
    for I := 0 to Objects.Count - 1 do
      with Objects[I] do
        if (aType = doAll) or
          (IsLink and (aType = doLinks)) or
          (not IsLink and (aType = doNodes)) then
          Draw(Canvas);
  end;

begin
  (* MW *)
  case DrawObjectOrder of
    ooNodesFirst: DrawObjects(doNodes);
    ooLinksFirst: DrawObjects(doLinks);
  end;

  if Linking and ((State = gsMoveLink) or
    ((CommandMode = cmLinkNodes) and (FirstNodeOfLink <> nil))) then
  begin
    Canvas.Pen.Mode := pmNot;
    Canvas.Pen.Width := 1;
    Canvas.Pen.Style := psSolid;
    DefaultLinkClass.DrawDraft(Canvas,
      Rect(StartPoint.X, StartPoint.Y, StopPoint.X, StopPoint.Y));
  end;

  (* MW *)
  case DrawObjectOrder of
    ooNodesFirst: DrawObjects(doLinks);
    ooLinksFirst: DrawObjects(doNodes);
  else
    DrawObjects(doAll);
  end;

  if Linking and (CommandMode = cmLinkNodes) and (FirstNodeOfLink <> 
nil) then
  ...
  ...