making Lidar - step 04 : Refresh Screen

360도마다 스크린을 새로 시작하게 만들기.

# -*- coding: utf-8 -*-
"""
From main library's example, ScatterPlot.py, 
I will take out one of chart to make it for Lidar data display.
"""
from pyqtgraph.Qt import QtGui, QtCore
import pyqtgraph as pg
import numpy as np
from collections import namedtuple
from itertools import chain
import sys

app = QtGui.QApplication([])
mw = QtGui.QMainWindow()
mw.resize(530,500)
view = pg.GraphicsLayoutWidget()  ## GraphicsView with GraphicsLayout inserted by default
mw.setCentralWidget(view)
mw.show()
mw.setWindowTitle('Lidar Test, unit in mm')

## create areas to add plots
w1 = view.addPlot()
  
###### Refresh Screen   
def RefreshScreen():
   # Add polar grid lines
   w1.clear()   # clear screen and start drawing basic lines
   w1.addLine(x=0, pen=0.3)  # draw vertical center line
   w1.addLine(y=0, pen=0.3)  # draw horizontal center line
   for radius in range(200, 2000, 200):   # Draw 9 circles 200 ~ 2000 step 200
      # Adding circle (x, y, width, height)
      circleWidth = radius * 2
      circleHeight = radius * 2
      circle = pg.QtGui.QGraphicsEllipseItem(-radius, -radius, circleWidth, circleHeight)
      circle.setPen(pg.mkPen(0.3))
      w1.addItem(circle)  # addItem means draw or plot.  Here, draw circle
   
######  I have to focus on putting data here.   
def _update():
   RefreshScreen()  # Draw basic graph with no data dots
   
   n = 360
   
   s1 = pg.ScatterPlotItem(size=5, pen=pg.mkPen(None), brush=pg.mkBrush(255, 255, 255, 120))
   # Make 2 Dimension (X,Y) points array of 360 dots on scale of 500 for 500 mm.
   pos = np.random.normal(size=(2,n), scale=500)
   spots = [{'pos': pos[:,i], 'data': 1} for i in range(n)] + [{'pos': [0,0], 'data': 1}]
   s1.addPoints(spots)
   # addItem means draw or plot.  Here, plot all points
   w1.addItem(s1, ignoreBounds = True)  # ignoreBounds will prevent annoying rescaling
   

timer = QtCore.QTimer(interval=1)
timer.timeout.connect(_update)
timer.start(500)  # duration number in millisecond

# RefreshScreen()  # Calling once, later it will be called from _update every 360 degree
_update()   # Calling only once, timer will keep calling them 


if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()