Restricting line to be connected

VCL TMS Diagram Studio
1

I would like to restrict lines on the drawing all to be connected to linkpoints, and after that also restrict which linkpoints can be joined.

I started to code the OnAcceptLink event handler, but I discovered that this event is never fired if I draw a line in the middle of nowhere. without connection any blocks.
Any suggestion ?

2

Use property RequiresConnections to prevent lines to be inserted without being connected to some link point. Then continue using OnAcceptLink to filter which link points are accepted or not.

3

Where can I set it ? Is there any event fired when the Link is going to be created ?

4

RequiresConnection is a property of TDiagramLine object. You must set it for each line in your diagram.

Event OnInsertLink is fired whenever a new line is added to the diagram.
5

I've tried adding 

  ALink.RequiresConnections:=true;
in the OnInsertLink event, but the editor still allows me to draw connections on an empty diagram.
I'm using the latest version with delphi 7.
6

This should work. Can you send me a compilable project through support e-mail so I can check what is wrong?

7

I'll package and send it, I think this 2 pics says it all...


8
Problem is when the OnInsertLink is called the line is already inserted. You must set Requiresconnections before the line is inserted. Here is one way of doing that:

 
type
  TMyDiagramLine = class(TDiagramLine)
  public
    constructor Create(AOwner: TComponent); override;
  end;


constructor TMyDiagramLine.Create(AOwner: TComponent);
begin
  inherited;
  RequiresConnections := true;
end;


procedure TForm1.FormCreate(Sender: TObject);
begin
  // Replace TDiagramLine type by my own TMyDiagramLine
  RegDControlList.FindByID('TDiagramLine').DControlClass := MyDiagramLine;
end;
9

ok that works thaks!