draw2d on drag start event

Question

I want to call my custom callback function every time, when user starts dragging figures. I tried to do it like so:

figure.onDragStart = function (x, y, shiftKey, ctrlKey) {
    myfunc();
};

But the problem is, every time when my function is called, figure is positioned to 0,0 coordinate. I'm not sure what is wrong with that and how can I fix it.

yes, sure. it may be just `function myfunc(){ console.log("Hello world") }`. So, it is just an arbitrary function. — Jacobian, Aug 15 '17 at 14:33
Have you tried adding `return true;` to `figure.onDragStart`? — Nelson Yeung, Aug 15 '17 at 14:50
I've just tried `figure.onDragStart = function () { return true; }` and got the very same effect. So, it seems like the library itself positions the figure to `0,0` point when this event is fired. — Jacobian, Aug 15 '17 at 14:58

ConnorsFan · Accepted Answer · 2017-08-21T00:38:11.100

Instead of redefining the onDragStart method, you can handle the dragstart event:

figure.on("dragstart", function(event, ui) {
    // Do something
});

According to the draw2d documentation, that event is triggered by onDragStart. The ui parameter contains x, y, shiftKey and ctrlKey.

You can see the code in action in this jsfiddle. A message is displayed in the console when you start dragging a rectangle. The green rectangle uses the dragstart event and responds correctly. The red one redefines the onDragStart method, with the problem mentioned in your question.

draw2d on drag start event

1 Answers1