Add initial image viewer

An image session will be opened by project.buildEditSession()
for known image extensions.

Closes #203

src/app/image-edit-session.coffee

@@ -0,0 +1,33 @@
+fsUtils = require 'fs-utils'
+
+module.exports=
+class ImageEditSession
+  registerDeserializer(this)
+
+  @deserialize: (state) ->
+    if fsUtils.exists(state.path)
+      project.buildEditSession(state.path)
+    else
+      console.warn "Could not build edit session for path '#{state.path}' because that file no longer exists"
+
+  constructor: (@path) ->
+
+  serialize: ->
+    deserializer: 'ImageEditSession'
+    path: @path
+
+  getViewClass: ->
+    require 'image-view'
+
+  getTitle: ->
+    if path = @getPath()
+      fsUtils.base(path)
+    else
+      'untitled'
+
+  getUri: -> @path
+
+  getPath: -> @path
+
+  isEqual: (other) ->
+    other instanceof ImageEditSession and @getUri() is other.getUri()

src/app/image-view.coffee

@@ -0,0 +1,43 @@
+ScrollView = require 'scroll-view'
+
+module.exports =
+class ImageView extends ScrollView
+  @content: ->
+    @div class: 'image-view', tabindex: -1, =>
+      @img outlet: 'image'
+
+  initialize: (imageEditSession) ->
+    requireStylesheet 'image-view'
+
+    @image.load => @updateSize()
+    @setPath(imageEditSession?.getPath())
+
+  afterAttach: (onDom) ->
+    return unless onDom
+
+    if pane = @getPane()
+      @active = @is(pane.activeView)
+      @subscribe pane, 'pane:active-item-changed', (event, item) =>
+        wasActive = @active
+        @active = @is(pane.activeView)
+        @updateSize() if @active and not wasActive
+
+  updateSize: ->
+    return unless @isVisible()
+
+    @image.css
+      'margin-left': -@image.width() / 2
+      'margin-top': -@image.height() / 2
+    @image.show()
+
+  setPath: (path) ->
+    if path?
+      @image.hide().attr('src', path) if @image.attr('src') isnt path
+    else
+      @image.hide()
+
+  setModel: (imageEditSession) ->
+    @setPath(imageEditSession?.getPath())
+
+  getPane: ->
+    @parent('.item-views').parent('.pane').view()

src/app/project.coffee

@@ -4,6 +4,7 @@ $ = require 'jquery'
 Range = require 'range'
 Buffer = require 'text-buffer'
 EditSession = require 'edit-session'
+ImageEditSession = require 'image-edit-session'
 EventEmitter = require 'event-emitter'
 Directory = require 'directory'
 BufferedProcess = require 'buffered-process'
@@ -85,7 +86,10 @@ class Project
   setSoftWrap: (@softWrap) ->
 
   buildEditSession: (filePath, editSessionOptions={}) ->
-    @buildEditSessionForBuffer(@bufferForPath(filePath), editSessionOptions)
+    if fsUtils.isImageExtension(fsUtils.extension(filePath))
+      new ImageEditSession(filePath)
+    else
+      @buildEditSessionForBuffer(@bufferForPath(filePath), editSessionOptions)
 
   buildEditSessionForBuffer: (buffer, editSessionOptions) ->
     options = _.extend(@defaultEditSessionOptions(), editSessionOptions)