src/Stage.ts
import { Util } from './Util';
import { Factory } from './Factory';
import { Container, ContainerConfig } from './Container';
import { Konva } from './Global';
import { SceneCanvas, HitCanvas } from './Canvas';
import { GetSet, Vector2d } from './types';
import { Shape } from './Shape';
import { Layer } from './Layer';
import { DD } from './DragAndDrop';
import { _registerNode } from './Global';
import * as PointerEvents from './PointerEvents';
export interface StageConfig extends ContainerConfig {
container: HTMLDivElement | string;
}
// CONSTANTS
var STAGE = 'Stage',
STRING = 'string',
PX = 'px',
MOUSEOUT = 'mouseout',
MOUSELEAVE = 'mouseleave',
MOUSEOVER = 'mouseover',
MOUSEENTER = 'mouseenter',
MOUSEMOVE = 'mousemove',
MOUSEDOWN = 'mousedown',
MOUSEUP = 'mouseup',
POINTERMOVE = 'pointermove',
POINTERDOWN = 'pointerdown',
POINTERUP = 'pointerup',
POINTERCANCEL = 'pointercancel',
LOSTPOINTERCAPTURE = 'lostpointercapture',
POINTEROUT = 'pointerout',
POINTERLEAVE = 'pointerleave',
POINTEROVER = 'pointerover',
POINTERENTER = 'pointerenter',
CONTEXTMENU = 'contextmenu',
TOUCHSTART = 'touchstart',
TOUCHEND = 'touchend',
TOUCHMOVE = 'touchmove',
TOUCHCANCEL = 'touchcancel',
WHEEL = 'wheel',
MAX_LAYERS_NUMBER = 5,
EVENTS = [
[MOUSEENTER, '_pointerenter'],
[MOUSEDOWN, '_pointerdown'],
[MOUSEMOVE, '_pointermove'],
[MOUSEUP, '_pointerup'],
[MOUSELEAVE, '_pointerleave'],
[TOUCHSTART, '_pointerdown'],
[TOUCHMOVE, '_pointermove'],
[TOUCHEND, '_pointerup'],
[TOUCHCANCEL, '_pointercancel'],
[MOUSEOVER, '_pointerover'],
[WHEEL, '_wheel'],
[CONTEXTMENU, '_contextmenu'],
[POINTERDOWN, '_pointerdown'],
[POINTERMOVE, '_pointermove'],
[POINTERUP, '_pointerup'],
[POINTERCANCEL, '_pointercancel'],
[LOSTPOINTERCAPTURE, '_lostpointercapture'],
];
const EVENTS_MAP = {
mouse: {
[POINTEROUT]: MOUSEOUT,
[POINTERLEAVE]: MOUSELEAVE,
[POINTEROVER]: MOUSEOVER,
[POINTERENTER]: MOUSEENTER,
[POINTERMOVE]: MOUSEMOVE,
[POINTERDOWN]: MOUSEDOWN,
[POINTERUP]: MOUSEUP,
[POINTERCANCEL]: 'mousecancel',
pointerclick: 'click',
pointerdblclick: 'dblclick',
},
touch: {
[POINTEROUT]: 'touchout',
[POINTERLEAVE]: 'touchleave',
[POINTEROVER]: 'touchover',
[POINTERENTER]: 'touchenter',
[POINTERMOVE]: TOUCHMOVE,
[POINTERDOWN]: TOUCHSTART,
[POINTERUP]: TOUCHEND,
[POINTERCANCEL]: TOUCHCANCEL,
pointerclick: 'tap',
pointerdblclick: 'dbltap',
},
pointer: {
[POINTEROUT]: POINTEROUT,
[POINTERLEAVE]: POINTERLEAVE,
[POINTEROVER]: POINTEROVER,
[POINTERENTER]: POINTERENTER,
[POINTERMOVE]: POINTERMOVE,
[POINTERDOWN]: POINTERDOWN,
[POINTERUP]: POINTERUP,
[POINTERCANCEL]: POINTERCANCEL,
pointerclick: 'pointerclick',
pointerdblclick: 'pointerdblclick',
},
};
const getEventType = (type) => {
if (type.indexOf('pointer') >= 0) {
return 'pointer';
}
if (type.indexOf('touch') >= 0) {
return 'touch';
}
return 'mouse';
};
const getEventsMap = (eventType: string) => {
const type = getEventType(eventType);
if (type === 'pointer') {
return Konva.pointerEventsEnabled && EVENTS_MAP.pointer;
}
if (type === 'touch') {
return EVENTS_MAP.touch;
}
if (type === 'mouse') {
return EVENTS_MAP.mouse;
}
};
function checkNoClip(attrs: any = {}) {
if (attrs.clipFunc || attrs.clipWidth || attrs.clipHeight) {
Util.warn(
'Stage does not support clipping. Please use clip for Layers or Groups.'
);
}
return attrs;
}
const NO_POINTERS_MESSAGE = `Pointer position is missing and not registered by the stage. Looks like it is outside of the stage container. You can set it manually from event: stage.setPointersPositions(event);`;
export const stages: Stage[] = [];
/**
* Stage constructor. A stage is used to contain multiple layers
* @constructor
* @memberof Konva
* @augments Konva.Container
* @param {Object} config
* @param {String|Element} config.container Container selector or DOM element
* @@nodeParams
* @example
* var stage = new Konva.Stage({
* width: 500,
* height: 800,
* container: 'containerId' // or "#containerId" or ".containerClass"
* });
*/
export class Stage extends Container<Layer> {
content: HTMLDivElement;
pointerPos: Vector2d | null;
_pointerPositions: (Vector2d & { id?: number })[] = [];
_changedPointerPositions: (Vector2d & { id: number })[] = [];
bufferCanvas: SceneCanvas;
bufferHitCanvas: HitCanvas;
_mouseTargetShape: Shape;
_touchTargetShape: Shape;
_pointerTargetShape: Shape;
_mouseClickStartShape: Shape;
_touchClickStartShape: Shape;
_pointerClickStartShape: Shape;
_mouseClickEndShape: Shape;
_touchClickEndShape: Shape;
_pointerClickEndShape: Shape;
_mouseDblTimeout: any;
_touchDblTimeout: any;
_pointerDblTimeout: any;
constructor(config: StageConfig) {
super(checkNoClip(config));
this._buildDOM();
this._bindContentEvents();
stages.push(this);
this.on('widthChange.konva heightChange.konva', this._resizeDOM);
this.on('visibleChange.konva', this._checkVisibility);
this.on(
'clipWidthChange.konva clipHeightChange.konva clipFuncChange.konva',
() => {
checkNoClip(this.attrs);
}
);
this._checkVisibility();
}
_validateAdd(child) {
const isLayer = child.getType() === 'Layer';
const isFastLayer = child.getType() === 'FastLayer';
const valid = isLayer || isFastLayer;
if (!valid) {
Util.throw('You may only add layers to the stage.');
}
}
_checkVisibility() {
if (!this.content) {
return;
}
const style = this.visible() ? '' : 'none';
this.content.style.display = style;
}
/**
* set container dom element which contains the stage wrapper div element
* @method
* @name Konva.Stage#setContainer
* @param {DomElement} container can pass in a dom element or id string
*/
setContainer(container) {
if (typeof container === STRING) {
if (container.charAt(0) === '.') {
var className = container.slice(1);
container = document.getElementsByClassName(className)[0];
} else {
var id;
if (container.charAt(0) !== '#') {
id = container;
} else {
id = container.slice(1);
}
container = document.getElementById(id);
}
if (!container) {
throw 'Can not find container in document with id ' + id;
}
}
this._setAttr('container', container);
if (this.content) {
if (this.content.parentElement) {
this.content.parentElement.removeChild(this.content);
}
container.appendChild(this.content);
}
return this;
}
shouldDrawHit() {
return true;
}
/**
* clear all layers
* @method
* @name Konva.Stage#clear
*/
clear() {
var layers = this.children,
len = layers.length,
n;
for (n = 0; n < len; n++) {
layers[n].clear();
}
return this;
}
clone(obj?) {
if (!obj) {
obj = {};
}
obj.container =
typeof document !== 'undefined' && document.createElement('div');
return Container.prototype.clone.call(this, obj) as this;
}
destroy() {
super.destroy();
var content = this.content;
if (content && Util._isInDocument(content)) {
this.container().removeChild(content);
}
var index = stages.indexOf(this);
if (index > -1) {
stages.splice(index, 1);
}
Util.releaseCanvas(this.bufferCanvas._canvas, this.bufferHitCanvas._canvas);
return this;
}
/**
* returns ABSOLUTE pointer position which can be a touch position or mouse position
* pointer position doesn't include any transforms (such as scale) of the stage
* it is just a plain position of pointer relative to top-left corner of the canvas
* @method
* @name Konva.Stage#getPointerPosition
* @returns {Vector2d|null}
*/
getPointerPosition(): Vector2d | null {
const pos = this._pointerPositions[0] || this._changedPointerPositions[0];
if (!pos) {
Util.warn(NO_POINTERS_MESSAGE);
return null;
}
return {
x: pos.x,
y: pos.y,
};
}
_getPointerById(id?: number) {
return this._pointerPositions.find((p) => p.id === id);
}
getPointersPositions() {
return this._pointerPositions;
}
getStage() {
return this;
}
getContent() {
return this.content;
}
_toKonvaCanvas(config) {
config = config || {};
config.x = config.x || 0;
config.y = config.y || 0;
config.width = config.width || this.width();
config.height = config.height || this.height();
var canvas = new SceneCanvas({
width: config.width,
height: config.height,
pixelRatio: config.pixelRatio || 1,
});
var _context = canvas.getContext()._context;
var layers = this.children;
if (config.x || config.y) {
_context.translate(-1 * config.x, -1 * config.y);
}
layers.forEach(function (layer) {
if (!layer.isVisible()) {
return;
}
var layerCanvas = layer._toKonvaCanvas(config);
_context.drawImage(
layerCanvas._canvas,
config.x,
config.y,
layerCanvas.getWidth() / layerCanvas.getPixelRatio(),
layerCanvas.getHeight() / layerCanvas.getPixelRatio()
);
});
return canvas;
}
/**
* get visible intersection shape. This is the preferred
* method for determining if a point intersects a shape or not
* @method
* @name Konva.Stage#getIntersection
* @param {Object} pos
* @param {Number} pos.x
* @param {Number} pos.y
* @returns {Konva.Node}
* @example
* var shape = stage.getIntersection({x: 50, y: 50});
*/
getIntersection(pos: Vector2d) {
if (!pos) {
return null;
}
var layers = this.children,
len = layers.length,
end = len - 1,
n;
for (n = end; n >= 0; n--) {
const shape = layers[n].getIntersection(pos);
if (shape) {
return shape;
}
}
return null;
}
_resizeDOM() {
var width = this.width();
var height = this.height();
if (this.content) {
// set content dimensions
this.content.style.width = width + PX;
this.content.style.height = height + PX;
}
this.bufferCanvas.setSize(width, height);
this.bufferHitCanvas.setSize(width, height);
// set layer dimensions
this.children.forEach((layer) => {
layer.setSize({ width, height });
layer.draw();
});
}
add(layer: Layer, ...rest) {
if (arguments.length > 1) {
for (var i = 0; i < arguments.length; i++) {
this.add(arguments[i]);
}
return this;
}
super.add(layer);
var length = this.children.length;
if (length > MAX_LAYERS_NUMBER) {
Util.warn(
'The stage has ' +
length +
' layers. Recommended maximum number of layers is 3-5. Adding more layers into the stage may drop the performance. Rethink your tree structure, you can use Konva.Group.'
);
}
layer.setSize({ width: this.width(), height: this.height() });
// draw layer and append canvas to container
layer.draw();
if (Konva.isBrowser) {
this.content.appendChild(layer.canvas._canvas);
}
// chainable
return this;
}
getParent() {
return null;
}
getLayer() {
return null;
}
hasPointerCapture(pointerId: number): boolean {
return PointerEvents.hasPointerCapture(pointerId, this);
}
setPointerCapture(pointerId: number) {
PointerEvents.setPointerCapture(pointerId, this);
}
releaseCapture(pointerId: number) {
PointerEvents.releaseCapture(pointerId, this);
}
/**
* returns an array of layers
* @method
* @name Konva.Stage#getLayers
*/
getLayers() {
return this.children;
}
_bindContentEvents() {
if (!Konva.isBrowser) {
return;
}
EVENTS.forEach(([event, methodName]) => {
this.content.addEventListener(
event,
(evt) => {
this[methodName](evt);
},
{ passive: false }
);
});
}
_pointerenter(evt: PointerEvent) {
this.setPointersPositions(evt);
const events = getEventsMap(evt.type);
if (events) {
this._fire(events.pointerenter, {
evt: evt,
target: this,
currentTarget: this,
});
}
}
_pointerover(evt) {
this.setPointersPositions(evt);
const events = getEventsMap(evt.type);
if (events) {
this._fire(events.pointerover, {
evt: evt,
target: this,
currentTarget: this,
});
}
}
_getTargetShape(evenType) {
let shape: Shape | null = this[evenType + 'targetShape'];
if (shape && !shape.getStage()) {
shape = null;
}
return shape;
}
_pointerleave(evt) {
const events = getEventsMap(evt.type);
const eventType = getEventType(evt.type);
if (!events) {
return;
}
this.setPointersPositions(evt);
var targetShape = this._getTargetShape(eventType);
var eventsEnabled =
!(Konva.isDragging() || Konva.isTransforming()) || Konva.hitOnDragEnabled;
if (targetShape && eventsEnabled) {
targetShape._fireAndBubble(events.pointerout, { evt: evt });
targetShape._fireAndBubble(events.pointerleave, { evt: evt });
this._fire(events.pointerleave, {
evt: evt,
target: this,
currentTarget: this,
});
this[eventType + 'targetShape'] = null;
} else if (eventsEnabled) {
this._fire(events.pointerleave, {
evt: evt,
target: this,
currentTarget: this,
});
this._fire(events.pointerout, {
evt: evt,
target: this,
currentTarget: this,
});
}
this.pointerPos = null;
this._pointerPositions = [];
}
_pointerdown(evt: TouchEvent | MouseEvent | PointerEvent) {
const events = getEventsMap(evt.type);
const eventType = getEventType(evt.type);
if (!events) {
return;
}
this.setPointersPositions(evt);
var triggeredOnShape = false;
this._changedPointerPositions.forEach((pos) => {
var shape = this.getIntersection(pos);
DD.justDragged = false;
// probably we are staring a click
Konva['_' + eventType + 'ListenClick'] = true;
// no shape detected? do nothing
if (!shape || !shape.isListening()) {
return;
}
if (Konva.capturePointerEventsEnabled) {
shape.setPointerCapture(pos.id);
}
// save where we started the click
this[eventType + 'ClickStartShape'] = shape;
shape._fireAndBubble(events.pointerdown, {
evt: evt,
pointerId: pos.id,
});
triggeredOnShape = true;
// TODO: test in iframe
// only call preventDefault if the shape is listening for events
const isTouch = evt.type.indexOf('touch') >= 0;
if (shape.preventDefault() && evt.cancelable && isTouch) {
evt.preventDefault();
}
});
// trigger down on stage if not already
if (!triggeredOnShape) {
this._fire(events.pointerdown, {
evt: evt,
target: this,
currentTarget: this,
pointerId: this._pointerPositions[0].id,
});
}
}
_pointermove(evt: TouchEvent | MouseEvent | PointerEvent) {
const events = getEventsMap(evt.type);
const eventType = getEventType(evt.type);
if (!events) {
return;
}
if (Konva.isDragging() && DD.node!.preventDefault() && evt.cancelable) {
evt.preventDefault();
}
this.setPointersPositions(evt);
var eventsEnabled =
!(Konva.isDragging() || Konva.isTransforming()) || Konva.hitOnDragEnabled;
if (!eventsEnabled) {
return;
}
var processedShapesIds = {};
let triggeredOnShape = false;
var targetShape = this._getTargetShape(eventType);
this._changedPointerPositions.forEach((pos) => {
const shape = (PointerEvents.getCapturedShape(pos.id) ||
this.getIntersection(pos)) as Shape;
const pointerId = pos.id;
const event = { evt: evt, pointerId };
var differentTarget = targetShape !== shape;
if (differentTarget && targetShape) {
targetShape._fireAndBubble(events.pointerout, { ...event }, shape);
targetShape._fireAndBubble(events.pointerleave, { ...event }, shape);
}
if (shape) {
if (processedShapesIds[shape._id]) {
return;
}
processedShapesIds[shape._id] = true;
}
if (shape && shape.isListening()) {
triggeredOnShape = true;
if (differentTarget) {
shape._fireAndBubble(events.pointerover, { ...event }, targetShape);
shape._fireAndBubble(events.pointerenter, { ...event }, targetShape);
this[eventType + 'targetShape'] = shape;
}
shape._fireAndBubble(events.pointermove, { ...event });
} else {
if (targetShape) {
this._fire(events.pointerover, {
evt: evt,
target: this,
currentTarget: this,
pointerId,
});
this[eventType + 'targetShape'] = null;
}
}
});
if (!triggeredOnShape) {
this._fire(events.pointermove, {
evt: evt,
target: this,
currentTarget: this,
pointerId: this._changedPointerPositions[0].id,
});
}
}
_pointerup(evt) {
const events = getEventsMap(evt.type);
const eventType = getEventType(evt.type);
if (!events) {
return;
}
this.setPointersPositions(evt);
const clickStartShape = this[eventType + 'ClickStartShape'];
const clickEndShape = this[eventType + 'ClickEndShape'];
var processedShapesIds = {};
let triggeredOnShape = false;
this._changedPointerPositions.forEach((pos) => {
const shape = (PointerEvents.getCapturedShape(pos.id) ||
this.getIntersection(pos)) as Shape;
if (shape) {
shape.releaseCapture(pos.id);
if (processedShapesIds[shape._id]) {
return;
}
processedShapesIds[shape._id] = true;
}
const pointerId = pos.id;
const event = { evt: evt, pointerId };
let fireDblClick = false;
if (Konva['_' + eventType + 'InDblClickWindow']) {
fireDblClick = true;
clearTimeout(this[eventType + 'DblTimeout']);
} else if (!DD.justDragged) {
// don't set inDblClickWindow after dragging
Konva['_' + eventType + 'InDblClickWindow'] = true;
clearTimeout(this[eventType + 'DblTimeout']);
}
this[eventType + 'DblTimeout'] = setTimeout(function () {
Konva['_' + eventType + 'InDblClickWindow'] = false;
}, Konva.dblClickWindow);
if (shape && shape.isListening()) {
triggeredOnShape = true;
this[eventType + 'ClickEndShape'] = shape;
shape._fireAndBubble(events.pointerup, { ...event });
// detect if click or double click occurred
if (
Konva['_' + eventType + 'ListenClick'] &&
clickStartShape &&
clickStartShape === shape
) {
shape._fireAndBubble(events.pointerclick, { ...event });
if (fireDblClick && clickEndShape && clickEndShape === shape) {
shape._fireAndBubble(events.pointerdblclick, { ...event });
}
}
} else {
this[eventType + 'ClickEndShape'] = null;
if (Konva['_' + eventType + 'ListenClick']) {
this._fire(events.pointerclick, {
evt: evt,
target: this,
currentTarget: this,
pointerId,
});
}
if (fireDblClick) {
this._fire(events.pointerdblclick, {
evt: evt,
target: this,
currentTarget: this,
pointerId,
});
}
}
});
if (!triggeredOnShape) {
this._fire(events.pointerup, {
evt: evt,
target: this,
currentTarget: this,
pointerId: this._changedPointerPositions[0].id,
});
}
Konva['_' + eventType + 'ListenClick'] = false;
// always call preventDefault for desktop events because some browsers
// try to drag and drop the canvas element
// TODO: are we sure we need to prevent default at all?
// do not call this function on mobile because it prevent "click" event on all parent containers
// but apps may listen to it.
if (evt.cancelable && eventType !== 'touch') {
evt.preventDefault();
}
}
_contextmenu(evt) {
this.setPointersPositions(evt);
var shape = this.getIntersection(this.getPointerPosition()!);
if (shape && shape.isListening()) {
shape._fireAndBubble(CONTEXTMENU, { evt: evt });
} else {
this._fire(CONTEXTMENU, {
evt: evt,
target: this,
currentTarget: this,
});
}
}
_wheel(evt) {
this.setPointersPositions(evt);
var shape = this.getIntersection(this.getPointerPosition()!);
if (shape && shape.isListening()) {
shape._fireAndBubble(WHEEL, { evt: evt });
} else {
this._fire(WHEEL, {
evt: evt,
target: this,
currentTarget: this,
});
}
}
_pointercancel(evt: PointerEvent) {
this.setPointersPositions(evt);
const shape =
PointerEvents.getCapturedShape(evt.pointerId) ||
this.getIntersection(this.getPointerPosition()!);
if (shape) {
shape._fireAndBubble(POINTERUP, PointerEvents.createEvent(evt));
}
PointerEvents.releaseCapture(evt.pointerId);
}
_lostpointercapture(evt: PointerEvent) {
PointerEvents.releaseCapture(evt.pointerId);
}
/**
* manually register pointers positions (mouse/touch) in the stage.
* So you can use stage.getPointerPosition(). Usually you don't need to use that method
* because all internal events are automatically registered. It may be useful if event
* is triggered outside of the stage, but you still want to use Konva methods to get pointers position.
* @method
* @name Konva.Stage#setPointersPositions
* @param {Object} event Event object
* @example
*
* window.addEventListener('mousemove', (e) => {
* stage.setPointersPositions(e);
* });
*/
setPointersPositions(evt) {
var contentPosition = this._getContentPosition(),
x: number | null = null,
y: number | null = null;
evt = evt ? evt : window.event;
// touch events
if (evt.touches !== undefined) {
// touchlist has not support for map method
// so we have to iterate
this._pointerPositions = [];
this._changedPointerPositions = [];
Array.prototype.forEach.call(evt.touches, (touch: any) => {
this._pointerPositions.push({
id: touch.identifier,
x: (touch.clientX - contentPosition.left) / contentPosition.scaleX,
y: (touch.clientY - contentPosition.top) / contentPosition.scaleY,
});
});
Array.prototype.forEach.call(
evt.changedTouches || evt.touches,
(touch: any) => {
this._changedPointerPositions.push({
id: touch.identifier,
x: (touch.clientX - contentPosition.left) / contentPosition.scaleX,
y: (touch.clientY - contentPosition.top) / contentPosition.scaleY,
});
}
);
} else {
// mouse events
x = (evt.clientX - contentPosition.left) / contentPosition.scaleX;
y = (evt.clientY - contentPosition.top) / contentPosition.scaleY;
this.pointerPos = {
x: x,
y: y,
};
this._pointerPositions = [{ x, y, id: Util._getFirstPointerId(evt) }];
this._changedPointerPositions = [
{ x, y, id: Util._getFirstPointerId(evt) },
];
}
}
_setPointerPosition(evt) {
Util.warn(
'Method _setPointerPosition is deprecated. Use "stage.setPointersPositions(event)" instead.'
);
this.setPointersPositions(evt);
}
_getContentPosition() {
if (!this.content || !this.content.getBoundingClientRect) {
return {
top: 0,
left: 0,
scaleX: 1,
scaleY: 1,
};
}
var rect = this.content.getBoundingClientRect();
return {
top: rect.top,
left: rect.left,
// sometimes clientWidth can be equals to 0
// i saw it in react-konva test, looks like it is because of hidden testing element
scaleX: rect.width / this.content.clientWidth || 1,
scaleY: rect.height / this.content.clientHeight || 1,
};
}
_buildDOM() {
this.bufferCanvas = new SceneCanvas({
width: this.width(),
height: this.height(),
});
this.bufferHitCanvas = new HitCanvas({
pixelRatio: 1,
width: this.width(),
height: this.height(),
});
if (!Konva.isBrowser) {
return;
}
var container = this.container();
if (!container) {
throw 'Stage has no container. A container is required.';
}
// clear content inside container
container.innerHTML = '';
// content
this.content = document.createElement('div');
this.content.style.position = 'relative';
this.content.style.userSelect = 'none';
this.content.className = 'konvajs-content';
this.content.setAttribute('role', 'presentation');
container.appendChild(this.content);
this._resizeDOM();
}
// currently cache function is now working for stage, because stage has no its own canvas element
cache() {
Util.warn(
'Cache function is not allowed for stage. You may use cache only for layers, groups and shapes.'
);
return this;
}
clearCache() {
return this;
}
/**
* batch draw
* @method
* @name Konva.Stage#batchDraw
* @return {Konva.Stage} this
*/
batchDraw() {
this.getChildren().forEach(function (layer) {
layer.batchDraw();
});
return this;
}
container: GetSet<HTMLDivElement, this>;
}
Stage.prototype.nodeType = STAGE;
_registerNode(Stage);
/**
* get/set container DOM element
* @method
* @name Konva.Stage#container
* @returns {DomElement} container
* @example
* // get container
* var container = stage.container();
* // set container
* var container = document.createElement('div');
* body.appendChild(container);
* stage.container(container);
*/
Factory.addGetterSetter(Stage, 'container');