feat: applyToPoint()

docs/README.md

@@ -20,6 +20,7 @@ These matrices can be used for matrix calcuations on SVG CTMs (current transform
             * [.isInvertible()](#module_immutable-transform-matrix..Matrix+isInvertible) ⇒ <code>boolean</code>
             * [.inverse()](#module_immutable-transform-matrix..Matrix+inverse) ⇒ <code>Matrix</code>
             * [.divide(m)](#module_immutable-transform-matrix..Matrix+divide) ⇒ <code>Matrix</code>
+            * [.applyToPoint(x, y)](#module_immutable-transform-matrix..Matrix+applyToPoint) ⇒ <code>Object</code>
         * _static_
             * [.Matrix](#module_immutable-transform-matrix..Matrix.Matrix)
                 * [new Matrix(a, b, c, d, e, f)](#new_module_immutable-transform-matrix..Matrix.Matrix_new)
@@ -44,6 +45,7 @@ These matrices can be used for matrix calcuations on SVG CTMs (current transform
         * [.isInvertible()](#module_immutable-transform-matrix..Matrix+isInvertible) ⇒ <code>boolean</code>
         * [.inverse()](#module_immutable-transform-matrix..Matrix+inverse) ⇒ <code>Matrix</code>
         * [.divide(m)](#module_immutable-transform-matrix..Matrix+divide) ⇒ <code>Matrix</code>
+        * [.applyToPoint(x, y)](#module_immutable-transform-matrix..Matrix+applyToPoint) ⇒ <code>Object</code>
     * _static_
         * [.Matrix](#module_immutable-transform-matrix..Matrix.Matrix)
             * [new Matrix(a, b, c, d, e, f)](#new_module_immutable-transform-matrix..Matrix.Matrix_new)
@@ -163,6 +165,19 @@ Multiplies current matrix with an other matrix.
 | --- | --- | --- |
 | m | <code>Matrix</code> | matrix divisor |
 
+<a name="module_immutable-transform-matrix..Matrix+applyToPoint"></a>
+
+#### matrix.applyToPoint(x, y) ⇒ <code>Object</code>
+Apply current matrix to x and y point.
+
+**Kind**: instance method of [<code>Matrix</code>](#module_immutable-transform-matrix..Matrix)  
+**Returns**: <code>Object</code> - A new transformed point object  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| x | <code>number</code> | value for x |
+| y | <code>number</code> | value for y |
+
 <a name="module_immutable-transform-matrix..Matrix.Matrix"></a>
 
 #### Matrix.Matrix

package.json

@@ -20,7 +20,7 @@
     "lint": "standard src/*.js",
     "lint:fix": "npm run lint -- --fix",
     "test": "jest --coverage && cat ./coverage/lcov.info | coveralls",
-    "test:dev": "npm run test -- --watch",
+    "test:dev": "jest --watch",
     "prepublish": "npm run clean & npm run build",
     "docs": "jsdoc2md src/index.js > docs/README.md",
     "semantic-release": "semantic-release pre && npm publish && semantic-release post"

src/index.js

@@ -229,6 +229,20 @@ class Matrix extends Map {
       inverse.get('f')
     )
   }
+
+  /**
+   * Apply current matrix to x and y point.
+   *
+   * @param {number} x - value for x
+   * @param {number} y - value for y
+   * @returns {{x: number, y: number}} A new transformed point object
+   */
+  applyToPoint (x, y) {
+    return {
+      x: (x * this.get('a')) + (y * this.get('c')) + this.get('e'),
+      y: (x * this.get('b')) + (y * this.get('d')) + this.get('f')
+    }
+  }
 }
 
 export default Matrix

src/index.spec.js

@@ -161,3 +161,11 @@ describe('divide', () => {
     }).toThrow()
   })
 })
+
+describe('#applyToPoint', () => {
+  it('should compute the dot product and return a plain object', () => {
+    const x = 5
+    const y = 6
+    expect(new Matrix().applyToPoint(x, y)).toEqual({x, y})
+  })
+})