Provide a paste-manager api to customize final delta.

src/modules/paste-manager.coffee

@@ -5,23 +5,34 @@ dom      = Quill.require('dom')
 Delta    = Quill.require('delta')
 
 class PasteManager
-  constructor: (@quill, @options) ->
+  @DEFAULTS:
+    onConvert: null
+
+  constructor: (@quill, options) ->
     @container = @quill.addContainer('ql-paste-manager')
     @container.setAttribute('contenteditable', true)
     dom(@quill.root).on('paste', _.bind(this._paste, this))
+    @options = _.defaults(options, PasteManager.DEFAULTS)
+    @options.onConvert ?= this._onConvert;
+
+  _onConvert: (container) =>
+    doc = new Document(container, @quill.options)
+    delta = doc.toDelta()
+    lengthAdded = delta.length()
+    if lengthAdded == 0
+      return delta
+    # Need to remove trailing newline so paste is inline, losing format is expected and observed in Word
+    return delta.compose(new Delta().retain(lengthAdded - 1).delete(1))
 
   _paste: ->
     oldDocLength = @quill.getLength()
     range = @quill.getSelection()
     return unless range?
     @container.focus()
     _.defer( =>
-      doc = new Document(@container, @quill.options)
-      delta = doc.toDelta()
-      lengthAdded = Math.max(0, delta.length() - 1)
+      delta = @options.onConvert(@container)
+      lengthAdded = delta.length()
       if lengthAdded > 0
-        # Need to remove trailing newline so paste is inline, losing format is expected and observed in Word
-        delta = delta.compose(new Delta().retain(lengthAdded).delete(1))
         delta.ops.unshift({ retain: range.start }) if range.start > 0
         delta.delete(range.end - range.start)
         @quill.updateContents(delta, 'user')

test/unit/modules/paste-manager.coffee

@@ -23,4 +23,42 @@ describe('PasteManager', ->
       )
     )
   )
+
+  it('optionally allows custom delta creation', (done) ->
+    container = $('#editor-container').get(0)
+    container.innerHTML = '
+      <div>
+        <div>0123</div>
+      </div>'
+    quill = new Quill(container.firstChild, {
+      modules: {
+        'paste-manager': {
+          onConvert: ->
+            new Quill.Delta().insert('something else', {
+              italic: true
+            })
+        }
+      }
+    })
+    pasteManager = quill.getModule('paste-manager')
+    quill.setSelection(2, 2)
+    pasteManager._paste()
+    pasteManager.container.innerHTML = '
+      <b>Pasted</b>
+      <div style="text-align: right;">Text</div>
+    '
+    quill.on(Quill.events.TEXT_CHANGE, (delta) ->
+      expect(delta).toEqualDelta(
+        new Quill.Delta()
+        .retain(2)
+        .insert('something else', { italic: true })
+      )
+      _.defer( ->
+        range = quill.getSelection()
+        expect(range.start).toEqual(16)
+        expect(range.end).toEqual(16)
+        done()
+      )
+    )
+  )
 )