如何在draw2d中的特定位置添加图形？

Question

I want to add label at start or end position of connection. But here I did not found locator except ManhattanMidpointLocator. So how can I do this? How can I place label at where on connection?
Please find my code as below,

draw2d.LabelConnection = function() {
  draw2d.Connection.call(this);
  this.sourcePort = null;
  this.targetPort = null;
  this.lineSegments = [];
  this.setColor(new draw2d.Color(0, 255, 0));
  this.setLineWidth(2);

  var label = new draw2d.Label("Message");
  label.setBackgroundColor(new draw2d.Color(230, 230, 250));
  label.setBorder(new draw2d.LineBorder(1));
  this.addFigure(label, new draw2d.Locator());
};

draw2d.LabelConnection.prototype = new draw2d.Connection();
draw2d.LabelConnection.prototype.type = "draw2d.LabelConnection";

The above code shows label at (0,0) position. plz help me out.

Answer 1

I'm not sure about what you mean by "any location" but if you implement your own locator it's pretty straightforward.

Look at the code of the ManhattanMidpointLocator. In the relocate function you know everything about the connection on the canvas. From that you just invent a calculation for the position of the label.

Answer 2

Now working with Graphiti in place of Draw2D but the code for your locator should look as follow (didn't tested) :

draw2d.StartConnectionLocator=function(/*:draw2d.Connection*/ connection)
{
  draw2d.ConnectionLocator.call(this,connection);
};
draw2d.StartConnectionLocator.prototype.relocate=function(/*:draw2d.Figure*/ target)
{
   var conn = this.getConnection();

   var points = conn.getPoints();
   var index = Math.floor((points.getSize() -2) / 2);
   if (points.getSize() <= index+1)
      return; 

   var startPoint = points.get(0);
   var myPosition = new draw2d.Point();
   myPosition.x = startPoint.x +5;
   myPosition.y = startPoint.y +5;

   target.setPosition(myPosition.x,myPosition.y);
};

Answer 3

Use:

Connection.getStartPoint() to determine the start poit of the connection instead to retrieve all segments of the connection.

Greetings