Merge Item#_remove() and Layer#_remove().

And add Project#_changed(), so it can be called through #_getOwner().

src/item/Item.js

@@ -208,24 +208,8 @@ var Item = Base.extend(Emitter, /** @lends Item# */{
             // child triggers this notification on the parent.
             Item._clearBoundsCache(this);
         }
-        if (project) {
-            if (flags & /*#=*/ChangeFlag.APPEARANCE) {
-                project._needsUpdate = true;
-            }
-            // Have project keep track of changed items so they can be iterated.
-            // This can be used for example to update the SVG tree. Needs to be
-            // activated in Project
-            if (project._changes) {
-                var entry = project._changesById[this._id];
-                if (entry) {
-                    entry.flags |= flags;
-                } else {
-                    entry = { item: this, flags: flags };
-                    project._changesById[this._id] = entry;
-                    project._changes.push(entry);
-                }
-            }
-        }
+        if (project)
+            project._changed(flags, this);
         // If this item is a symbol's definition, notify it of the change too
         if (symbol)
             symbol._changed(flags);
@@ -1081,15 +1065,10 @@ var Item = Base.extend(Emitter, /** @lends Item# */{
 
     setMatrix: function() {
         // Use Matrix#initialize to easily copy over values.
+        // NOTE: calling initialize() also calls #_changed() for us, through its
+        // call to #set() / #reset(), and this also handles _applyMatrix for us.
         var matrix = this._matrix;
         matrix.initialize.apply(matrix, arguments);
-        if (this._applyMatrix) {
-            // Directly apply the internal matrix. This will also call
-            // _changed() for us.
-            this.transform(null, true);
-        } else {
-            this._changed(/*#=*/Change.GEOMETRY);
-        }
     },
 
     /**
@@ -2389,23 +2368,25 @@ var Item = Base.extend(Emitter, /** @lends Item# */{
      * Removes the item from its parent's children list.
      */
     _remove: function(notifySelf, notifyParent) {
-        var parent = this._parent;
-        if (parent) {
+        var owner = this._getOwner(),
+            project = this._project,
+            index = this._index;
+        if (owner && index != null) {
+            // Only required for layers, but not enough to merit an override.
+            if (project._activeLayer === this)
+                project._activeLayer = this.getNextSibling()
+                        || this.getPreviousSibling();
             if (this._name)
                 this._removeNamed();
-            if (this._index != null)
-                Base.splice(parent._children, null, this._index, 1);
+            Base.splice(owner._children, null, index, 1);
             this._installEvents(false);
             // Notify self of the insertion change. We only need this
             // notification if we're tracking changes for now.
-            if (notifySelf) {
-                var project = this._project;
-                if (project && project._changes)
-                    this._changed(/*#=*/Change.INSERTION);
-            }
-            // Notify parent of changed children
+            if (notifySelf && project._changes)
+                this._changed(/*#=*/Change.INSERTION);
+            // Notify owner of changed children (this can be the project too).
             if (notifyParent)
-                parent._changed(/*#=*/Change.CHILDREN);
+                owner._changed(/*#=*/Change.CHILDREN, this);
             this._parent = null;
             return true;
         }

src/item/Layer.js

@@ -68,42 +68,12 @@ var Layer = Group.extend(/** @lends Layer# */{
 
     /**
      * Private helper to return the owner, either the parent, or the project
-     * for top-level layers.
+     * for top-level layers, if they are inserted in it.
      */
     _getOwner: function() {
         return this._parent || this._index != null && this._project;
     },
 
-    /**
-     * Removes the layer from its project's layers list
-     * or its parent's children list.
-     */
-    _remove: function _remove(notifySelf, notifyParent) {
-        if (this._parent)
-            return _remove.base.call(this, notifySelf, notifyParent);
-        if (this._index != null) {
-            var project = this._project;
-            if (project._activeLayer === this)
-                project._activeLayer = this.getNextSibling()
-                        || this.getPreviousSibling();
-            Base.splice(project._children, null, this._index, 1);
-            this._installEvents(false);
-            // Notify self of the insertion change. We only need this
-            // notification if we're tracking changes for now.
-            if (notifySelf && project._changes)
-                this._changed(/*#=*/Change.INSERTION);
-            // Notify parent of changed children
-            if (notifyParent) {
-                // TODO: project._changed(/*#=*/Change.LAYERS);
-                // Tell project we need a redraw. This is similar to _changed()
-                // mechanism.
-                project._needsUpdate = true;
-            }
-            return true;
-        }
-        return false;
-    },
-
     isInserted: function isInserted() {
         return this._parent ? isInserted.base.call(this) : this._index != null;
     },

src/project/Project.js

@@ -80,6 +80,32 @@ var Project = PaperScopeItem.extend(/** @lends Project# */{
         return Base.serialize(this._children, options, true, dictionary);
     },
 
+    /**
+     * Private notifier that is called whenever a change occurs in the project.
+     *
+     * @param {ChangeFlag} flags describes what exactly has changed
+     * @param {Item} item the item that has caused the change
+     */
+    _changed: function(flags, item) {
+        if (flags & /*#=*/ChangeFlag.APPEARANCE) {
+            this._needsUpdate = true;
+        }
+        // Have project keep track of changed items so they can be iterated.
+        // This can be used for example to update the SVG tree. Needs to be
+        // activated in Project
+        var changes = this._changes;
+        if (changes && item) {
+            var changesById = this._changesById,
+                id = item._id,
+                entry = changesById[id];
+            if (entry) {
+                entry.flags |= flags;
+            } else {
+                changes.push(changesById[id] = { item: item, flags: flags });
+            }
+        }
+    },
+
     /**
      * Activates this project, so all newly created items will be placed
      * in it.

src/project/Symbol.js

@@ -93,13 +93,11 @@ var Symbol = Base.extend(/** @lends Symbol# */{
      * @param {ChangeFlag} flags describes what exactly has changed
      */
     _changed: function(flags) {
-        if (flags & /*#=*/ChangeFlag.GEOMETRY) {
+        if (flags & /*#=*/ChangeFlag.GEOMETRY)
             // Clear cached bounds of all items that this symbol is linked to.
             Item._clearBoundsCache(this);
-        }
-        if (flags & /*#=*/ChangeFlag.APPEARANCE) {
-            this.project._needsUpdate = true;
-        }
+        if (flags & /*#=*/ChangeFlag.APPEARANCE)
+            this.project._changed(flags);
     },
 
     /**

src/view/View.js

@@ -265,8 +265,7 @@ var View = Base.extend(Emitter, /** @lends View# */{
      * @param {ChangeFlag} flags describes what exactly has changed
      */
     _changed: function(flags) {
-        if (flags & /*#=*/ChangeFlag.APPEARANCE)
-            this._project._needsUpdate = true;
+        this._project._changed(flats);
     },
 
     _transform: function(matrix) {