Waveform ImageData Node

waveform.coffee

app.get '/waveform', (req, res) ->
  
  # If URL and Callback present
  if req.param("url") && req.param("callback")
  
    # Get the parameters
    url       = decodeURIComponent(req.param("url"))
    callback  = req.param("callback")
  
    # Create a Bufferlist
    bl = new BufferList()
  
    # Request image and pass response to Bufferlist
    request { uri: url, responseBodyStream: bl, encoding: null }, (error, response, body) ->
    
      # console.log response.headers['content-type']
    
      # If the request was OK
      if !error && response.statusCode == 200
    
        # Get MimeType
        mimetype = response.headers["content-type"]
            
        # Make sure it's a PNG    
        if mimetype == "image/png"
    
          # Create the prefix for the data URL
          type_prefix = "data:" + mimetype + ";base64,"
    
          # Get the image from the response stream as a string and convert it to base64
          # image     = new Buffer(bl.toString(), 'binary')
          image     = new Buffer(body)
          image_64  = body.toString('base64')
          
          # Concat the prefix and the image
          image_64  = type_prefix + image_64
    
          # Get the image filename
          filename = "/tmp/" + url.substring( url.lastIndexOf('/') + 1 )
    
          # Create a WriteStream for the image
          out = fs.createWriteStream(filename)
          
          # Save it
          out.write(image)
          # out.write(body)
          out.end()
    
          # Get the image dimensions using GraphicsMagick
          im.identify filename, (err, data) ->
           
            # Delete the tmp image
            fs.unlink(filename)
      
            # Error getting dimensions
            if err
              res.send("Error getting image dimensions", 400)
            else
      
              # The data to be returned
              return_variable =
                "width": data.width
                "height": data.height
                "data": image_64
          
              # Stringifiy the return variable and wrap it in the callback for JSONP compatibility
              return_variable = callback + "(" + JSON.stringify(return_variable) + ");"

              # Set the headers as OK and JS
              res.writeHead(200, 'Content-Type': 'application/javascript; charset=UTF-8')

              # Return the data
              res.end(return_variable)
              
        else
          res.send("This file type is not supported", 400)
      else
        res.send("Third-party server error", response.statusCode)
  else
    res.send("No URL or no callback was specified. These are required", 400)