Texture.add will no longer let you add a frame to a texture with th…

…e same name or index as one that already exists in the texture. Doing so will now return `null` instead of a Frame object, and the `frameTotal` will never be incremented. Fix #4459

CHANGELOG.md

@@ -103,6 +103,7 @@ Notes:
 * `Tween.stop` assumed that the parent was the TweenManager. If the Tween has been added to the Timeline, that was not true and the stop method crashed (thanks @TadejZupancic)
 * Calling `Tween.restart` multiple times in a row would cause the tween to freeze. It will now disregard all additional calls to `restart` if it's already in a pending state (thanks @rgk)
 * Tween Timelines would only apply the `delay` value of a child tween once and not on loop. Fix #3841 (thanks @Edwin222 @Antriel)
+* `Texture.add` will no longer let you add a frame to a texture with the same name or index as one that already exists in the texture. Doing so will now return `null` instead of a Frame object, and the `frameTotal` will never be incremented. Fix #4459 (thanks @BigZaphod)
 
 ### Examples, Documentation and TypeScript
 

src/textures/Texture.js

@@ -137,6 +137,8 @@ var Texture = new Class({
      * Adds a new Frame to this Texture.
      *
      * A Frame is a rectangular region of a TextureSource with a unique index or string-based key.
+     * 
+     * The name given must be unique within this Texture. If it already exists, this method will return `null`.
      *
      * @method Phaser.Textures.Texture#add
      * @since 3.0.0
@@ -148,10 +150,15 @@ var Texture = new Class({
      * @param {number} width - The width of this Frame.
      * @param {number} height - The height of this Frame.
      *
-     * @return {Phaser.Textures.Frame} The Frame that was added to this Texture.
+     * @return {?Phaser.Textures.Frame} The Frame that was added to this Texture, or `null` if the given name already exists.
      */
     add: function (name, sourceIndex, x, y, width, height)
     {
+        if (this.has(name))
+        {
+            return null;
+        }
+
         var frame = new Frame(this, name, sourceIndex, x, y, width, height);
 
         this.frames[name] = frame;