refactor: Move validation logic to core

src/color-thief-node.js

@@ -28,13 +28,18 @@ function getColor(img, quality) {
 }
 
 function getPalette(img, colorCount = 10, quality = 10) {
+    const options = core.validateOptions({
+        colorCount,
+        quality
+    });
+
     return new Promise((resolve, reject) => {
         loadImg(img)
             .then(imgData => {
                 const pixelCount = imgData.shape[0] * imgData.shape[1];
-                const pixelArray = core.createPixelArray(imgData.data, pixelCount, quality);
+                const pixelArray = core.createPixelArray(imgData.data, pixelCount, options.quality);
 
-                const cmap = quantize(pixelArray, colorCount);
+                const cmap = quantize(pixelArray, options.colorCount);
                 const palette = cmap? cmap.palette() : null;
 
                 resolve(palette);

src/color-thief.js

@@ -31,17 +31,11 @@ import core from './core.js';
 var CanvasImage = function (image) {
     this.canvas  = document.createElement('canvas');
     this.context = this.canvas.getContext('2d');
-
     this.width  = this.canvas.width  = image.width;
     this.height = this.canvas.height = image.height;
-
     this.context.drawImage(image, 0, 0, this.width, this.height);
 };
 
-CanvasImage.prototype.getPixelCount = function () {
-    return this.width * this.height;
-};
-
 CanvasImage.prototype.getImageData = function () {
     return this.context.getImageData(0, 0, this.width, this.height);
 };
@@ -86,25 +80,22 @@ ColorThief.prototype.getColor = function(sourceImage, quality = 10) {
  *
  */
 ColorThief.prototype.getPalette = function(sourceImage, colorCount, quality) {
-
-    if (typeof colorCount === 'undefined' || colorCount < 2 || colorCount > 256) {
-        colorCount = 10;
-    }
-    if (typeof quality === 'undefined' || quality < 1) {
-        quality = 10;
-    }
+    const options = core.validateOptions({
+        colorCount,
+        quality
+    });
 
     // Create custom CanvasImage object
     var image      = new CanvasImage(sourceImage);
     var imageData  = image.getImageData();
     var pixels     = imageData.data;
-    var pixelCount = image.getPixelCount();
+    var pixelCount = image.width * image.height;
 
-    const pixelArray = core.createPixelArray(imageData, pixelCount, quality);
+    const pixelArray = core.createPixelArray(imageData.data, pixelCount, options.quality);
 
     // Send array to quantize function which clusters values
     // using median cut algorithm
-    var cmap    = quantize(pixelArray, colorCount);
+    var cmap    = quantize(pixelArray, options.colorCount);
     var palette = cmap? cmap.palette() : null;
 
     return palette;

src/core-node.js

@@ -19,6 +19,31 @@ function createPixelArray(imgData, pixelCount, quality) {
     return pixelArray;
 }
 
+function validateOptions(options) {
+    let { colorCount, quality } = options;
+
+    if (typeof colorCount === 'undefined' || !Number.isInteger(colorCount)) {
+        colorCount = 10;
+    } else if (colorCount === 1 ) {
+        throw new Error('colorCount should be between 2 and 20. To get one color, call getColor() instead of getPalette()');
+    } else {
+        colorCount = Math.max(colorCount, 2);
+        colorCount = Math.min(colorCount, 20);
+    }
+
+    if (typeof quality === 'undefined' || Number.isInteger(quality)) {
+        quality = 10;
+    } else if (quality < 1) {
+        quality = 10;
+    }
+
+    return {
+        colorCount,
+        quality
+    }
+}
+
 module.exports = {
-    createPixelArray
+    createPixelArray,
+    validateOptions
 };

src/core.js

@@ -19,6 +19,31 @@ function createPixelArray(imgData, pixelCount, quality) {
     return pixelArray;
 }
 
+function validateOptions(options) {
+    let { colorCount, quality } = options;
+
+    if (typeof colorCount === 'undefined' || !Number.isInteger(colorCount)) {
+        colorCount = 10;
+    } else if (colorCount === 1 ) {
+        throw new Error('colorCount should be between 2 and 20. To get one color, call getColor() instead of getPalette()');
+    } else {
+        colorCount = Math.max(colorCount, 2);
+        colorCount = Math.min(colorCount, 20);
+    }
+
+    if (typeof quality === 'undefined' || Number.isInteger(quality)) {
+        quality = 10;
+    } else if (quality < 1) {
+        quality = 10;
+    }
+
+    return {
+        colorCount,
+        quality
+    }
+}
+
 export default {
     createPixelArray,
-}
+    validateOptions
+};