function getShapeClass(name) {
    if (_customShapeMap.hasOwnProperty(name)) {
        return _customShapeMap[name];
    }
}
Sub pixel optimize for canvas

@param {number} position Coordinate, such as x, y
@param {number} lineWidth Should be nonnegative integer.
@param {boolean=} positiveOrNegative Default false (negative).
@return {number} Optimized position.