Merge pull request #4457 from atom/mb-text-editor-element-methods

Add `TextEditorElement` methods needed to replace deprecated APIs

spec/text-editor-element-spec.coffee

@@ -104,6 +104,27 @@ describe "TextEditorElement", ->
       scrollbarWidth = verticalScrollbarNode.offsetWidth - verticalScrollbarNode.clientWidth
       expect(scrollbarWidth).toEqual(8)
 
+  describe "::onDidAttach and ::onDidDetach", ->
+    it "invokes callbacks when the element is attached and detached", ->
+      element = new TextEditorElement
+
+      attachedCallback = jasmine.createSpy("attachedCallback")
+      detachedCallback = jasmine.createSpy("detachedCallback")
+
+      element.onDidAttach(attachedCallback)
+      element.onDidDetach(detachedCallback)
+
+      jasmine.attachToDOM(element)
+
+      expect(attachedCallback).toHaveBeenCalled()
+      expect(detachedCallback).not.toHaveBeenCalled()
+
+      attachedCallback.reset()
+      element.remove()
+
+      expect(attachedCallback).not.toHaveBeenCalled()
+      expect(detachedCallback).toHaveBeenCalled()
+
   describe "::setUpdatedSynchronously", ->
     it "controls whether the text editor is updated synchronously", ->
       spyOn(window, 'requestAnimationFrame').andCallFake (fn) -> fn()
@@ -124,3 +145,13 @@ describe "TextEditorElement", ->
       element.getModel().setText("goodbye")
       expect(window.requestAnimationFrame).not.toHaveBeenCalled()
       expect(element.shadowRoot.textContent).toContain "goodbye"
+
+  describe "::getDefaultCharacterWidth", ->
+    it "returns null before the element is attached", ->
+      element = new TextEditorElement
+      expect(element.getDefaultCharacterWidth()).toBeNull()
+
+    it "returns the width of a character in the root scope", ->
+      element = new TextEditorElement
+      jasmine.attachToDOM(element)
+      expect(element.getDefaultCharacterWidth()).toBeGreaterThan(0)

src/text-editor-element.coffee

@@ -1,3 +1,4 @@
+{Emitter} = require 'event-kit'
 {View, $, callRemoveHooks} = require 'space-pen'
 React = require 'react-atom-fork'
 Path = require 'path'
@@ -13,10 +14,12 @@ class TextEditorElement extends HTMLElement
   model: null
   componentDescriptor: null
   component: null
+  attached: false
   lineOverdrawMargin: null
   focusOnAttach: false
 
   createdCallback: ->
+    @emitter = new Emitter
     @initializeContent()
     @createSpacePenShim()
     @addEventListener 'focus', @focused.bind(this)
@@ -61,6 +64,10 @@ class TextEditorElement extends HTMLElement
     @mountComponent() unless @component?.isMounted()
     @component.checkForVisibilityChange()
     @focus() if @focusOnAttach
+    @emitter.emit("did-attach")
+
+  detachedCallback: ->
+    @emitter.emit("did-detach")
 
   initialize: (model) ->
     @setModel(model)
@@ -160,6 +167,24 @@ class TextEditorElement extends HTMLElement
 
   isUpdatedSynchronously: -> @updatedSynchronously
 
+  # Extended: get the width of a character of text displayed in this element.
+  #
+  # Returns a {Number} of pixels.
+  getDefaultCharacterWidth: ->
+    @getModel().getDefaultCharWidth()
+
+  # Extended: call the given `callback` when the editor is attached to the DOM.
+  #
+  # * `callback` {Function}
+  onDidAttach: (callback) ->
+    @emitter.on("did-attach", callback)
+
+  # Extended: call the given `callback` when the editor is detached from the DOM.
+  #
+  # * `callback` {Function}
+  onDidDetach: (callback) ->
+    @emitter.on("did-detach", callback)
+
 stopEventPropagation = (commandListeners) ->
   newCommandListeners = {}
   for commandName, commandListener of commandListeners