feat: isIdentity

HarryGogonis · Jun 25, 2017 · 4d39263 · 4d39263
1 parent c18f6e2
commit 4d39263
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diff --git a/src/index.js b/src/index.js
@@ -133,6 +133,18 @@ class Matrix extends Map {
     )
   }
 
+  /**
+   * @return {boolean} true if identity (no transforms applied)
+   */
+  isIdentity () {
+    return this.get('a') === 1
+      && this.get('b') === 0
+      && this.get('c') === 0
+      && this.get('d') === 1
+      && this.get('e') === 0
+      && this.get('f') === 0
+  }
+
   /**
    * @return {string}
    */

diff --git a/src/index.spec.js b/src/index.spec.js
@@ -101,6 +101,11 @@ describe('multiply', () => {
   })
 })
 
+describe('isIdentity', () => {
+  expect(mockMatrix.isIdentity()).toBe(false)
+  expect(new Matrix().isIdentity()).toBe(true)
+})
+
 describe('toString', () => {
   it('should return a matrix string', () => {
     let str = mockMatrix.toString()