image-contrast - npm Package Compare versions

Comparing version 0.0.6 to 0.0.7

index.js

@@ -1,7 +0,32 @@
-function copyImageData(ctx, src) {
-    var dst = ctx.createImageData(src.width, src.height);
-    dst.data.set(src.data);
-    return dst;
+/**
+ * @name getCanvas
+ * @param {number} w - width
+ * @param {number} h - height
+ * Create a canvas with the currect size
+ */
+function getCanvas(w, h) {
+    var canvas = document.createElement('canvas');
+    canvas.width = w;
+    canvas.height = h;
+
+    return canvas;
 }
 
+/**
+ * @name getPixels
+ * @param {object} canvas
+ * @param {object} context
+ * @param {object} imageData
+ * Get a deep copy of the image data so we don't change the original imageData
+ */
+function getPixels(canvas, context, imageData) {
+    context.putImageData(imageData, 0, 0);
+    return context.getImageData(0, 0, canvas.width, canvas.height);
+}
+
+/**
+ * @name getFactor
+ * @param {number} contrast
+ * Get the contrast factor based on the provided contrast value
+ */
 function getFactor(contrast) {
@@ -11,9 +36,17 @@ return (259 * (contrast + 255)) / (255 * (259 - contrast));
 
+/**
+ * @name transform
+ * @param {object} canvas
+ * @param {object} context
+ * @param {object} imageData
+ * @param {number} factor
+ * Iterate over the array applying the contrast transformation
+ */
 function transform(canvas, context, imageData, factor) {
     var data = imageData.data;
-    data.forEach(function (item, i) {
+    for (var i = 0; i < data.length; i+= 4) {
         data[i] = factor * (data[i] - 128) + 128;
         data[i+1] = factor * (data[i+1] - 128) + 128;
         data[i+2] = factor * (data[i+2] - 128) + 128;
-    });
+    }
 
@@ -33,11 +66,14 @@ context.putImageData(imageData, 0, 0);
     var result;
-    var canvas = document.createElement('canvas');
-    var context = canvas.getContext('2d');
+    var canvas;
+    var context;
 
     if (!options.data || !options.contrast) {
-        throw new Error('image-brightness:: invalid options provided');
+        throw new Error('image-contrast:: invalid options provided');
     }
 
-    options.data = copyImageData(context, options.data);
+    canvas = getCanvas(options.data.width, options.data.height);
+    context = canvas.getContext('2d');
 
+    options.data = getPixels(canvas, context, options.data);
+
     factor = getFactor(options.contrast)
@@ -44,0 +80,0 @@ result = transform(canvas, context, options.data, factor);

package.json

 {
   "name": "image-contrast",
-  "version": "0.0.6",
+  "version": "0.0.7",
   "description": "Small library to apply a contrast transformation to a image",
@@ -5,0 +5,0 @@ "main": "index.js",

sandbox/sandbox.js

@@ -16,6 +16,8 @@ var imageContrast = require('../index');
 
-    var canvas = document.createElement('canvas');
-    var context = canvas.getContext('2d');
     var img = new Image;
     img.onload = function(){
+        var canvas = document.createElement('canvas');
+        canvas.width = img.width;
+        canvas.height = img.height;
+        var context = canvas.getContext('2d');
         context.drawImage(img,0,0);
@@ -27,3 +29,3 @@
             data: data,
-            contrast: 30
+            contrast: 50
         });
@@ -34,3 +36,3 @@ applyResults('#target-1', results1);
             data: data,
-            contrast: 70
+            contrast: 100
         });
@@ -37,0 +39,0 @@ applyResults('#target-2', results2);

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Improved metrics

Total package byte prevSize

5686

increased by19.63%

Lines of code

101

increased by53.03%

No dependency changes