function createOrUpdateBarRect(bar, symbolMeta, isUpdate) {
	        var rectShape = zrUtil.extend({}, symbolMeta.barRectShape);

	        var barRect = bar.__pictorialBarRect;
	        if (!barRect) {
	            barRect = bar.__pictorialBarRect = new graphic.Rect({
	                z2: 2,
	                shape: rectShape,
	                silent: true,
	                style: {
	                    stroke: 'transparent',
	                    fill: 'transparent',
	                    lineWidth: 0
	                }
	            });

	            bar.add(barRect);
	        }
	        else {
	            updateAttr(barRect, null, {shape: rectShape}, symbolMeta, isUpdate);
	        }
	    }
Create single coordinate system and inject it into seriesModel.

@param {module:echarts/model/Global} ecModel
@param {module:echarts/ExtensionAPI} api
@return {Array.<module:echarts/coord/single/Single>}