Fixes #4

petereigenschink · Sep 22, 2017 · 025bd9a · 025bd9a
1 parent c304e34
commit 025bd9a
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Showing 9 changed files with 139 additions and 33 deletions.
diff --git a/.gitignore b/.gitignore
@@ -1,3 +1,4 @@
 dist
 docs
 node_modules
+.DS_Store
diff --git a/build/steganography.js b/build/steganography.js
@@ -1,5 +1,5 @@
 /*
- * steganography.js v1.0.2 2016-04-23
+ * steganography.js v1.0.3 2017-09-22
  *
  * Copyright (C) 2012 Peter Eigenschink (http://www.peter-eigenschink.at/)
  * Dual-licensed under MIT and Beerware license.
@@ -59,10 +59,10 @@ var util = {
   "loadImg": function(url) {
     var image = new Image();
     image.src = url;
-    while(image.hasOwnProperty('complete') && !image.complete) {}
     return image;
   }
 };
+
 Cover.prototype.config = {
   "t": 3,
   "threshold": 1,
@@ -94,8 +94,13 @@ Cover.prototype.getHidingCapacity = function(image, options) {
   return t*width*height/codeUnitSize >> 0;
 };
 Cover.prototype.encode = function(message, image, options) {
+  // Handle image url
   if(image.length) {
     image = util.loadImg(image);
+  } else if(image.src) {
+    image = util.loadImg(image.src);
+  } else if(!(image instanceof HTMLImageElement)) {
+    throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
   }
 
   options = options || {};
@@ -108,7 +113,7 @@ Cover.prototype.encode = function(message, image, options) {
     args = options.args || config.args,
     messageDelimiter = options.messageDelimiter || config.messageDelimiter;
 
-  if(!t || t < 1 || t > 7) throw "Error: Parameter t = " + t + " is not valid: 0 < t < 8";
+  if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
 
   var shadowCanvas = document.createElement('canvas'),
     shadowCtx = shadowCanvas.getContext('2d');
@@ -141,7 +146,10 @@ Cover.prototype.encode = function(message, image, options) {
     dec = message.charCodeAt(i) || 0;
     curOverlapping = (overlapping*i)%t;
     if(curOverlapping > 0 && oldDec) {
+      // Mask for the new character, shifted with the count of overlapping bits
       mask = Math.pow(2,t-curOverlapping) - 1;
+      // Mask for the old character, i.e. the t-curOverlapping bits on the right
+      // of that character
       oldMask = Math.pow(2, codeUnitSize) * (1 - Math.pow(2, -curOverlapping));
       left = (dec & mask) << curOverlapping;
       right = (oldDec & oldMask) >> (codeUnitSize - curOverlapping);
@@ -189,7 +197,7 @@ Cover.prototype.encode = function(message, image, options) {
     }
     for(i=offset*4; i<(offset+qS.length)*4 && i<data.length; i+=4)
       data[i+3] = qS[(i/4)%threshold];
-    
+
     subOffset = qS.length;
   }
   // Write message-delimiter
@@ -203,23 +211,29 @@ Cover.prototype.encode = function(message, image, options) {
 
   return shadowCanvas.toDataURL();
 };
+
 Cover.prototype.decode = function(image, options) {
+  // Handle image url
   if(image.length) {
     image = util.loadImg(image);
+  } else if(image.src) {
+    image = util.loadImg(image.src);
+  } else if(!(image instanceof HTMLImageElement)) {
+    throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
   }
 
   options = options || {};
   var config = this.config;
-  
+
   var t = options.t || config.t,
     threshold = options.threshold || config.threshold,
     codeUnitSize = options.codeUnitSize || config.codeUnitSize,
     prime = util.findNextPrime(Math.pow(2, t)),
-    args = options.args || config.args, 
+    args = options.args || config.args,
     messageCompleted = options.messageCompleted || config.messageCompleted;
 
-  if(!t || t < 1 || t > 7) throw "Error: Parameter t = " + t + " is not valid: 0 < t < 8";
-    
+  if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
+
   var shadowCanvas = document.createElement('canvas'),
     shadowCtx = shadowCanvas.getContext('2d');
 
@@ -306,5 +320,6 @@ Cover.prototype.decode = function(image, options) {
 
   return message;
 };
+
 return new Cover();
 });
diff --git a/build/steganography.min.js b/build/steganography.min.js
diff --git a/package.json b/package.json
@@ -7,7 +7,7 @@
     "type": "git",
     "url": "https://github.com/petereigenschink/steganography.js"
   },
-  "version": "1.0.2",
+  "version": "1.0.3",
   "license": "MIT",
   "devDependencies": {
     "grunt": "0.4.5",

diff --git a/src/decode.js b/src/decode.js
@@ -1,20 +1,25 @@
 Cover.prototype.decode = function(image, options) {
+  // Handle image url
   if(image.length) {
     image = util.loadImg(image);
+  } else if(image.src) {
+    image = util.loadImg(image.src);
+  } else if(!(image instanceof HTMLImageElement)) {
+    throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
   }
 
   options = options || {};
   var config = this.config;
-  
+
   var t = options.t || config.t,
     threshold = options.threshold || config.threshold,
     codeUnitSize = options.codeUnitSize || config.codeUnitSize,
     prime = util.findNextPrime(Math.pow(2, t)),
-    args = options.args || config.args, 
+    args = options.args || config.args,
     messageCompleted = options.messageCompleted || config.messageCompleted;
 
-  if(!t || t < 1 || t > 7) throw "Error: Parameter t = " + t + " is not valid: 0 < t < 8";
-    
+  if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
+
   var shadowCanvas = document.createElement('canvas'),
     shadowCtx = shadowCanvas.getContext('2d');
 
@@ -100,4 +105,4 @@ Cover.prototype.decode = function(image, options) {
   if(charCode !== 0) message += String.fromCharCode(charCode & mask);
 
   return message;
-};
+};
diff --git a/src/encode.js b/src/encode.js
@@ -1,6 +1,11 @@
 Cover.prototype.encode = function(message, image, options) {
+  // Handle image url
   if(image.length) {
     image = util.loadImg(image);
+  } else if(image.src) {
+    image = util.loadImg(image.src);
+  } else if(!(image instanceof HTMLImageElement)) {
+    throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
   }
 
   options = options || {};
@@ -13,7 +18,7 @@ Cover.prototype.encode = function(message, image, options) {
     args = options.args || config.args,
     messageDelimiter = options.messageDelimiter || config.messageDelimiter;
 
-  if(!t || t < 1 || t > 7) throw "Error: Parameter t = " + t + " is not valid: 0 < t < 8";
+  if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
 
   var shadowCanvas = document.createElement('canvas'),
     shadowCtx = shadowCanvas.getContext('2d');
@@ -46,7 +51,10 @@ Cover.prototype.encode = function(message, image, options) {
     dec = message.charCodeAt(i) || 0;
     curOverlapping = (overlapping*i)%t;
     if(curOverlapping > 0 && oldDec) {
+      // Mask for the new character, shifted with the count of overlapping bits
       mask = Math.pow(2,t-curOverlapping) - 1;
+      // Mask for the old character, i.e. the t-curOverlapping bits on the right
+      // of that character
       oldMask = Math.pow(2, codeUnitSize) * (1 - Math.pow(2, -curOverlapping));
       left = (dec & mask) << curOverlapping;
       right = (oldDec & oldMask) >> (codeUnitSize - curOverlapping);
@@ -94,7 +102,7 @@ Cover.prototype.encode = function(message, image, options) {
     }
     for(i=offset*4; i<(offset+qS.length)*4 && i<data.length; i+=4)
       data[i+3] = qS[(i/4)%threshold];
-    
+
     subOffset = qS.length;
   }
   // Write message-delimiter
@@ -107,4 +115,4 @@ Cover.prototype.encode = function(message, image, options) {
   shadowCtx.putImageData(imageData, 0, 0);
 
   return shadowCanvas.toDataURL();
-};
+};
diff --git a/src/util.js b/src/util.js
@@ -40,7 +40,6 @@ var util = {
   "loadImg": function(url) {
     var image = new Image();
     image.src = url;
-    while(image.hasOwnProperty('complete') && !image.complete) {}
     return image;
   }
-};
+};
diff --git a/test/js/steganography.js b/test/js/steganography.js
@@ -1,5 +1,5 @@
 /*
- * steganography.js v1.0.2 2016-04-23
+ * steganography.js v1.0.3 2017-09-22
  *
  * Copyright (C) 2012 Peter Eigenschink (http://www.peter-eigenschink.at/)
  * Dual-licensed under MIT and Beerware license.
@@ -59,10 +59,10 @@ var util = {
   "loadImg": function(url) {
     var image = new Image();
     image.src = url;
-    while(image.hasOwnProperty('complete') && !image.complete) {}
     return image;
   }
 };
+
 Cover.prototype.config = {
   "t": 3,
   "threshold": 1,
@@ -94,8 +94,13 @@ Cover.prototype.getHidingCapacity = function(image, options) {
   return t*width*height/codeUnitSize >> 0;
 };
 Cover.prototype.encode = function(message, image, options) {
+  // Handle image url
   if(image.length) {
     image = util.loadImg(image);
+  } else if(image.src) {
+    image = util.loadImg(image.src);
+  } else if(!(image instanceof HTMLImageElement)) {
+    throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
   }
 
   options = options || {};
@@ -108,7 +113,7 @@ Cover.prototype.encode = function(message, image, options) {
     args = options.args || config.args,
     messageDelimiter = options.messageDelimiter || config.messageDelimiter;
 
-  if(!t || t < 1 || t > 7) throw "Error: Parameter t = " + t + " is not valid: 0 < t < 8";
+  if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
 
   var shadowCanvas = document.createElement('canvas'),
     shadowCtx = shadowCanvas.getContext('2d');
@@ -141,7 +146,10 @@ Cover.prototype.encode = function(message, image, options) {
     dec = message.charCodeAt(i) || 0;
     curOverlapping = (overlapping*i)%t;
     if(curOverlapping > 0 && oldDec) {
+      // Mask for the new character, shifted with the count of overlapping bits
       mask = Math.pow(2,t-curOverlapping) - 1;
+      // Mask for the old character, i.e. the t-curOverlapping bits on the right
+      // of that character
       oldMask = Math.pow(2, codeUnitSize) * (1 - Math.pow(2, -curOverlapping));
       left = (dec & mask) << curOverlapping;
       right = (oldDec & oldMask) >> (codeUnitSize - curOverlapping);
@@ -189,7 +197,7 @@ Cover.prototype.encode = function(message, image, options) {
     }
     for(i=offset*4; i<(offset+qS.length)*4 && i<data.length; i+=4)
       data[i+3] = qS[(i/4)%threshold];
-    
+
     subOffset = qS.length;
   }
   // Write message-delimiter
@@ -203,23 +211,29 @@ Cover.prototype.encode = function(message, image, options) {
 
   return shadowCanvas.toDataURL();
 };
+
 Cover.prototype.decode = function(image, options) {
+  // Handle image url
   if(image.length) {
     image = util.loadImg(image);
+  } else if(image.src) {
+    image = util.loadImg(image.src);
+  } else if(!(image instanceof HTMLImageElement)) {
+    throw new Error('IllegalInput: The input image is neither an URL string nor an image.');
   }
 
   options = options || {};
   var config = this.config;
-  
+
   var t = options.t || config.t,
     threshold = options.threshold || config.threshold,
     codeUnitSize = options.codeUnitSize || config.codeUnitSize,
     prime = util.findNextPrime(Math.pow(2, t)),
-    args = options.args || config.args, 
+    args = options.args || config.args,
     messageCompleted = options.messageCompleted || config.messageCompleted;
 
-  if(!t || t < 1 || t > 7) throw "Error: Parameter t = " + t + " is not valid: 0 < t < 8";
-    
+  if(!t || t < 1 || t > 7) throw new Error('IllegalOptions: Parameter t = " + t + " is not valid: 0 < t < 8');
+
   var shadowCanvas = document.createElement('canvas'),
     shadowCtx = shadowCanvas.getContext('2d');
 
@@ -306,5 +320,6 @@ Cover.prototype.decode = function(image, options) {
 
   return message;
 };
+
 return new Cover();
 });