Visualize Math.random() in a canvas element

random-canvas.coffee

                                                                                                                    
#                                                                                                                        
# Visualize random data on a canvas element                                                                              
#                                                                                                                        
                                                                                                                         
$ ->                                                                                                                     
                                                                                                                         
  canvas = $ "#canvas"                                                                                                   
  ctxt   = canvas[0].getContext "2d"                                                                                     
                                                                                                                         
  blocksize = 32                                                                                                         
  height    = 3                                                                                                          
  width     = 8                                                                                                          
                                                                                                                         
  id = ctxt.createImageData 1, 1                                                                                         
  data = id.data                                                                                                         
                                                                                                                         
  rand = ->                                                                                                              
    Math.floor Math.random() * 256                                                                                       
                                                                                                                         
  setData = ->                                                                                                           
    for i in [0..3]                                                                                                      
      data[i] = rand()                                                                                                   
                                                                                                                         
  xOffset = 0                                                                                                            
  yOffset = 0                                                                                                            
                                                                                                                         
  fillBlock = ->                                                                                                         
    for x in [0..blocksize - 1]                                                                                          
      for y in [0..blocksize - 1]                                                                                        
        setData()                                                                                                        
        ctxt.putImageData id, x + xOffset, y + yOffset                                                                   
                                                                                                                         
  fillRow = ->                                                                                                           
    xOffset = 0                                                                                                          
    for x in [0..width]                                                                                                  
      fillBlock()                                                                                                        
      xOffset += blocksize                                                                                               
                                                                                                                         
  for y in [0..height]                                                                                                   
    fillRow()                                                                                                            
    yOffset += blocksize