src/dygraph-interaction-model.js
function(event, g) {
  var chartPos = utils.findPos(g.canvas_);
  var box = {
    left: chartPos.x,
    right: chartPos.x + g.canvas_.offsetWidth,
    top: chartPos.y,
    bottom: chartPos.y + g.canvas_.offsetHeight
  };

  var pt = {
    x: utils.pageX(event),
    y: utils.pageY(event)
  };

  var dx = distanceFromInterval(pt.x, box.left, box.right),
      dy = distanceFromInterval(pt.y, box.top, box.bottom);
  return Math.max(dx, dy);
}
function(event, g) {
  var chartPos = utils.findPos(g.canvas_);
  var box = {
    left: chartPos.x,
    right: chartPos.x + g.canvas_.offsetWidth,
    top: chartPos.y,
    bottom: chartPos.y + g.canvas_.offsetHeight
  };

  var pt = {
    x: utils.pageX(event),
    y: utils.pageY(event)
  };

  var dx = distanceFromInterval(pt.x, box.left, box.right),
      dy = distanceFromInterval(pt.y, box.top, box.bottom);
  return Math.max(dx, dy);
}
function ( event , g ) { var chartPos = utils . findPos ( g . canvas_ ) ; var box = { left : chartPos . x , right : chartPos . x + g . canvas_ . offsetWidth , top : chartPos . y , bottom : chartPos . y + g . canvas_ . offsetHeight } ; var pt = { x : utils . pageX ( event ) , y : utils . pageY ( event ) } ; var dx = distanceFromInterval ( pt . x , box . left , box . right ) , dy = distanceFromInterval ( pt . y , box . top , box . bottom ) ; return Math . max ( dx , dy ) ; }
Returns the number of pixels by which the event happens from the nearest
edge of the chart. For events in the interior of the chart, this returns zero.
Returns the number of pixels by which the event happens from the nearest edge of the chart . For events in the interior of the chart this returns zero .