增加解码方法

src/2d/math/Matrix.ts

 import {Point} from "././Point";
 import {HashObject} from "../HashObject";
-import {cos, DEG_TO_RAD, RAD_TO_DEG, sin} from "../const";
+import {cos, DEG_TO_RAD, PI_2, RAD_TO_DEG, sin} from "../const";
+import Transform from "./Transform";
 
 /**
  * 2维矩阵
@@ -421,6 +422,42 @@ export class Matrix extends HashObject {
 		return Math.round(Math.atan2(this.b, this.a) * RAD_TO_DEG);
 	}
 
+	decompose(transform: Transform) {
+		const a = this.a;
+		const b = this.b;
+		const c = this.c;
+		const d = this.d;
+		//取斜切
+		const skewX = -Math.atan2(-c, d);
+		const skewY = Math.atan2(b, a);
+
+		const delta = Math.abs(skewX + skewY);
+		//斜切值和旋转不唯一，所以设定条件只取其一
+		if (delta < 0.00001 || Math.abs(PI_2 - delta) < 0.00001) {
+			transform.rotation = skewY;
+			//考虑是否必要
+			if (a < 0 && d >= 0) {
+				transform.rotation += (transform.rotation <= 0) ? Math.PI : -Math.PI;
+			}
+			transform.skew.x = transform.skew.y = 0;
+		}
+		else {
+			transform.rotation = 0;
+			transform.skew.x = skewX;
+			transform.skew.y = skewY;
+		}
+
+		//取缩放
+		transform.scale.x = Math.sqrt((a * a) + (b * b));
+		transform.scale.y = Math.sqrt((c * c) + (d * d));
+
+		//取位置
+		transform.position.x = this.tx;
+		transform.position.y = this.ty;
+
+		return transform;
+	}
+
 	/**
 	 * Creates an array from the current Matrix object.与glsl中的mat3对应,注意行列主序执行transpose;
 	 *