I had a customer asking how he could make the lines in a LineSeries have a sensitivity to mouse proximity similar to the datapoints.
Here is what I came up with:

The essence of the solution was to extend the LineRenderer and draw an additional line with alpha=0, but of specified width, to the graphics object that the visible line is drawn on. That way mouse events will be dispatched by this line.

I figured the most logical place to specify the lineSensitivity attribute would be on the “Stroke” object, so I added that property to an extension of the Stroke class that I then access in my custom LineRenderer.

Here is the Stroke extension:

package
{
    import mx.graphics.Stroke;

    public class MyStroke extends Stroke
    {
        public function MyStroke(color:uint=0.0, weight:Number=0.0, alpha:Number=1.0, pixelHinting:Boolean=false, scaleMode:String="normal", caps:String=null, joints:String=null, miterLimit:Number=0.0)
        {
            super(color, weight, alpha, pixelHinting, scaleMode, caps, joints, miterLimit);
        }
       
        private var _lineSensitivity:Number=50;
   
        [Inspectable(category="General")]
   
        public function get lineSensitivity():Number
        {
            return _lineSensitivity;
        }
       
        /**
         *  @private
         */
        public function set lineSensitivity(value:Number):void
        {
            _lineSensitivity = value;
        }      
       
    }
}
 

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