random_noise.py

#!/usr/bin/env python
# encoding: utf-8

import sys

from PyQt4.QtCore import *
from PyQt4.QtGui import *
from random import randint, random
import Image, ImageQt

###############################################################################
class Canvas(QWidget):
  WIDTH = 300

  def __init__(self, parent=None):
    super(QWidget,self).__init__(parent)
    self.qwhite_noise = None
    self.white_noise = None
    self.qsignal = None
    self.signal = None
    self.square = (randint(0,Canvas.WIDTH-15), randint(0,Canvas.WIDTH-15), 15)
    self.bias = 0.25
    self.generate_white_noise()
    self.setFixedSize(QSize(Canvas.WIDTH*2+1,Canvas.WIDTH))

  def generate_white_noise(self):
    im = Image.new("L", (Canvas.WIDTH, Canvas.WIDTH))
    im.putdata([randint(0,1)*255 for x in im.getdata()])
    self.white_noise = im
    self.white_noise.save('/tmp/white_noise.bmp')
#    self.qwhite_noise = QPixmap.fromImage(ImageQt.ImageQt(im))
    self.qwhite_noise = QPixmap('/tmp/white_noise.bmp')
    self.redraw_square()

  def redraw_square(self):
    signal = self.white_noise.copy()
    x, y, length = self.square
    npixels = length*length

    # Generate a square with bias percent of white pixels
    nwhite = int(float(npixels)*self.bias + 0.5)
    square = [255]*nwhite + [0]*(npixels-nwhite)

    # Random pixel permutation
    for i in range(nwhite,len(square)):
      j = randint(0,i+1)
      square[i], square[j] = square[j], square[i]

    # Paste the square in the image
    sq = Image.new("L", (length,length))
    sq.putdata(square)
    signal.paste(sq,(x,y))

    self.signal = signal
    self.signal.save('/tmp/signal.bmp')
#    self.qsignal = QPixmap.fromImage(ImageQt.ImageQt(signal))
    self.qsignal = QPixmap('/tmp/signal.bmp')

    self.repaint()

  def paintEvent(self, e):
    paint = QPainter(self)
    paint.fillRect(self.rect(), QBrush(QColor(250,0,0)))
    if self.signal:
      paint.drawPixmap(QPoint(0,0),self.qsignal)
      paint.drawPixmap(QPoint(Canvas.WIDTH+1,0),self.qwhite_noise)

  def randomize_square_location(self):
    if self.square:
      x, y, len = self.square
      x = randint(0, Canvas.WIDTH-len)
      y = randint(0, Canvas.WIDTH-len)
      self.square = (x, y, len)
      print "x = ",x,", y = ",y
      self.redraw_square()

  def set_length(self, length):
    length = max(1, length)
    length = min(Canvas.WIDTH, length)
    if self.square:
      x, y, _ = self.square
      x = min(x, Canvas.WIDTH-length)
      y = min(y, Canvas.WIDTH-length)
      self.square = (x, y, length)
    else:
      self.square = (0, 0, length)
    self.redraw_square()

  def set_bias(self, bias):
    bias = max(0.0, bias)
    bias = min(1.0, bias)
    self.bias = bias
    self.redraw_square()

###############################################################################
class Window(QWidget):

  def __init__(self, title=None, parent = None):
    QWidget.__init__(self, parent)

    controlsLayout = QVBoxLayout()
    self.canvas = Canvas()
    controlsLayout.addWidget(self.canvas)
    controlsLayout.addWidget(QLabel(self.tr('bias')))
    controlsLayout.addWidget(QLabel(self.tr('length')))
    self.setLayout(controlsLayout)

  def keyPressEvent(self, event):
    if type(event) == QKeyEvent:
      c = event.key()

      if c == Qt.Key_Q:
        quit()
        event.accept()

      elif c == Qt.Key_R:
        self.canvas.randomize_square_location()
        event.accept()

    else:
      event.ignore()

###############################################################################
if __name__ == "__main__":
  import sys

  app = QApplication(sys.argv)
  window = Window()

  window.show()

  sys.exit(app.exec_())