增加getPromise返回一个Promise实例，此方法会中断链式编码

增加linear缓动

src/support/Tween.ts

@@ -31,10 +31,10 @@ export interface ITweenPlugin {
 	resolveLerp(fromValue, toValue, ratio, allowOutOfBounds): any;
 }
 
-function injectChildProps(target, key, value){
-	if(typeof value === 'object'){
+function injectChildProps(target, key, value) {
+	if (typeof value === 'object') {
 		injectProp(target[key], value)
-	}else{
+	} else {
 		target[key] = value;
 	}
 }
@@ -140,6 +140,7 @@ export class Tween extends HashObject {
 	protected duration: number;
 	protected onLoopComplete: Function;
 	protected onComplete: Function;
+	protected promise: any;
 
 	constructor(host: any, target: any, options?: TweenOptions, plugins = []) {
 		super();
@@ -162,7 +163,7 @@ export class Tween extends HashObject {
 	/**
 	 * 获取动画链(高级功能)
 	 */
-	get queue(){
+	get queue() {
 		return this._queue;
 	}
 
@@ -208,9 +209,9 @@ export class Tween extends HashObject {
 						currentValue = toValue;
 					}
 
-					if(typeof currentValue === 'object'){
+					if (typeof currentValue === 'object') {
 						injectProp(target[key], currentValue);
-					}else{
+					} else {
 						target[key] = currentValue;
 					}
 				}
@@ -229,15 +230,15 @@ export class Tween extends HashObject {
 		}
 	};
 
-	protected  getInitProps(fields) {
+	protected getInitProps(fields) {
 		const props = {};
 		for (let field of fields) {
 			if (field in this.target) {
 				let value = this.target[field];
-				if(typeof value === 'object'){
-					if(value.clone){
+				if (typeof value === 'object') {
+					if (value.clone) {
 						value = value.clone();
-					}else{
+					} else {
 						injectProp(props[field] = {}, this.target[field]);
 					}
 				}
@@ -251,13 +252,18 @@ export class Tween extends HashObject {
 	/**
 	 * 设置目标的属性
 	 * @param props 属性对象
+	 * @param immediately 是否立刻执行，而不是在下一帧
 	 */
-	set(props) {
+	set(props, immediately = false) {
 		this._queue.push({action: 'set', props});
 		if (this.autoPlay) {
 			this._start();
 		}
 
+		if (immediately) {
+			this._set(props, immediately);
+		}
+
 		return this;
 	}
 
@@ -267,7 +273,7 @@ export class Tween extends HashObject {
 	 * @param duration 耗时(ms)
 	 * @param ease 缓动方法
 	 */
-	to(props, duration?:number, ease?: Function) {
+	to(props, duration?: number, ease?: Function) {
 		this._queue.push({action: 'to', props, duration, ease});
 		if (this.autoPlay) {
 			this._start();
@@ -322,11 +328,6 @@ export class Tween extends HashObject {
 		}
 	}
 
-	private _doPlay = (resetLoopCounting) => {
-		addTween(this.target, this);
-		this._start(resetLoopCounting);
-	};
-
 	/**
 	 * 终止补间动画
 	 */
@@ -336,10 +337,26 @@ export class Tween extends HashObject {
 		this.host.cancelOnNextTick(this.onUpdate);
 	}
 
-	protected _set(props) {
-		this.status = STATUS.DO_SET;
+	/**
+	 * 返回一个Promise
+	 */
+	getPromise() {
+		return new Promise(resolve => {
+			this.promise = {resolve};
+		})
+	}
+
+	private _doPlay = (resetLoopCounting) => {
+		addTween(this.target, this);
+		this._start(resetLoopCounting);
+	};
+
+	protected _set(props, immediately = false) {
 		injectProp(this.target, props, injectChildProps);
-		this._doNextAction();
+		if (!immediately) {
+			this.status = STATUS.DO_SET;
+			this._doNextAction();
+		}
 	}
 
 	protected _to(props, duration, ease) {
@@ -349,10 +366,10 @@ export class Tween extends HashObject {
 		this.fromProps = {};
 		for (let key in props) {
 			let value = this.target[key];
-			if(typeof value === 'object'){
-				if(value.clone){
+			if (typeof value === 'object') {
+				if (value.clone) {
 					value = value.clone();
-				}else{
+				} else {
 					injectProp(props[key] = {}, this.target[key]);
 				}
 			}
@@ -377,7 +394,7 @@ export class Tween extends HashObject {
 
 	protected _call(func, thisObj, params) {
 		this.status = STATUS.DO_CALL;
-		func.apply(thisObj, params);
+		func.apply(thisObj || this.host, params);
 		this._doNextAction();
 	}
 
@@ -435,7 +452,7 @@ export class Tween extends HashObject {
 		}
 	};
 
-	protected _onEnd(){
+	protected _onEnd() {
 		this.onLoopComplete && this.onLoopComplete();
 		if (this.loop < 0) {
 			this._doStart();
@@ -444,6 +461,9 @@ export class Tween extends HashObject {
 		} else {
 			this.status = STATUS.IDLE;
 			this.onComplete && this.onComplete();
+
+			this.promise && this.promise.resolve();
+			this.promise = null;
 		}
 	}
 }
\ No newline at end of file

src/tools/ease.ts

@@ -5,6 +5,7 @@
  */
 
 export enum Ease {
+	linear = 'linear',
 	quadIn = 'quadIn',
 	quadOut = 'quadOut',
 	quadInOut = 'quadInOut',
@@ -34,6 +35,10 @@ export enum Ease {
 	elasticInOut = 'elasticInOut',
 }
 
+export function linear(t){
+	return t;
+}
+
 export function get(amount) {
 	if (amount < -1) {
 		amount = -1;