function Brush(model, ecModel, api) {
	        this.model = model;
	        this.ecModel = ecModel;
	        this.api = api;

	        /**
	         * @private
	         * @type {string}
	         */
	        this._brushType;

	        /**
	         * @private
	         * @type {string}
	         */
	        this._brushMode;
	    }
Convert a time data(time, value) item to (x, y) point.

@override
@param  {Array|number} data data
@param  {boolean} [clamp=true] out of range
@return {Array} point