if (this.getOption('highlightSeriesOpts')) {
ctx.clearRect(0, 0, this.width_, this.height_);
var alpha = 1.0 - this.getNumericOption('highlightSeriesBackgroundAlpha');
if (this.getOption('highlightSeriesOpts')) {
ctx.clearRect(0, 0, this.width_, this.height_);
var alpha = 1.0 - this.getNumericOption('highlightSeriesBackgroundAlpha');