new_contents: """
  * Copyright 2008 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
  *
  * http:#www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  """
  
  
  
  from pyjamas.Timer import Timer
  from pyjamas import Window
  from pyjamas.ui.Composite import Composite
  from pyjamas.ui.VerticalPanel import VerticalPanel
  from pyjamas.Canvas.ImageLoader import loadImages
  
  from SimpleCanvasDemo import SimpleCanvasDemo
  
  from pyjamas import log
  
  class LogoDemoControls(Composite):
      def __init__(self):
          Composite.__init__(self, VerticalPanel())
  
  """*
  * Demo Showcasing simple image rendering, transformations and animations.
  """
  class LogoDemo(SimpleCanvasDemo):
  
      """
      * Controls for the logo demo. We dont actually have any controls at the
      * moment, so we just initialize with an empty Vertical Panel.
      """
  
  
      def __init__(self, theCanvas):
          SimpleCanvasDemo.__init__(self, theCanvas)
          self.height = 400
          self.width = 600
          self.demoName = "GWT Logo"
  
          """
          * Reference to our ImageHandle that gets initialized on the callback from
          * ImageLoader.
          """
          self.img = None
  
          self.rotation = 0.1
  
          self.run = False
  
      def createControls(self):
          self.controls = LogoDemoControls()
  
  
      def drawDemo(self):
          # The following is the same as doing
          # self.canvas.resize(width,height)
          self.canvas.setCoordSize(self.width, self.height)
          self.canvas.setPixelHeight(self.height)
          self.canvas.setPixelWidth(self.width)
  
          imageUrls = ["pyjamas.128x128.png"]
  
  
          if self.img is None:
              # The first time this demo gets run we need to load our images.
              # Maintain a reference to the image we load so we can use it
              # the next time the demo is selected
              loadImages(imageUrls, self)
  
          else:
              # Go ahead and animate
              if isImageLoaded(self.img):
                  self.run = True
                  log.writebr("already loaded")
                  Timer(1, self)
              else:
                  Window.alert("Refresh the page to reload the image.")
  
  
      def onImagesLoaded(self, imageHandles):
          log.writebr("loaded")
          # Drawing code involving images goes here
          self.img = imageHandles[0]
          self.run = True
          Timer(1, self)
  
  
      def stopDemo(self):
          self.run = False
  
  
      def isImageLoaded(self, imgElem):
          return imgElem.__isLoaded
  
      def renderingLoop(self):
          self.canvas.saveContext()
  
          self.canvas.clear()
          # Draw a version of the logo, sampling the last 100x100
          # (image is 185x175) pixels of the image.
          # Draw starting at position 10, 10
          # scaled up by a factor of 2 on the self.canvas (using 200x200 as the
          # destination dimensions).
          self.canvas.drawImage(self.img, 84, 74, 100, 100, 10, 10, 200, 200)
  
          # draw an animated version
          self.canvas.translate(300, 200)
          self.canvas.rotate(self.rotation)
          self.canvas.scale(.9, .9)
  
          self.canvas.drawImage(self.img, 0, 0)
          self.rotation += 0.1
  
          self.canvas.restoreContext()
  
          log.writebr(str(self.rotation))
  
      def onTimer(self, tid):
          if not self.run:
              return
          self.renderingLoop()
          Timer(10, self)
  
  
  
subject: add GWTCanvas demo