This code is based on the Tcl
aniwave.tcl demo. A wave frequency line is drawn and animated, moving the frequency peak from right to left and back along the line.
# File: aniwave.py
# http://infohost.nmt.edu/tcc/help/pubs/tkinter//canvas.html#create_line
from tkinter import *
from tkinter import ttk
from demopanels import MsgPanel, SeeDismissPanel
class AnimatedWaveDemo(ttk.Frame):
def __init__(self, isapp=True, name='aniwavedemo'):
ttk.Frame.__init__(self, name=name)
self.pack(expand=Y, fill=BOTH)
self.master.title('Animated Wave Demo')
self.isapp = isapp
self._create_widgets()
def _create_widgets(self):
if self.isapp:
MsgPanel(self,
["This demonstration contains a canvas widget with a line item ",
"inside it. The animation routines work by adjusting the ",
"coordinates list of the line; which, in turn, changes the ",
"position of the frequency zig-zag on the line."])
SeeDismissPanel(self)
self._create_demo_panel()
def _create_demo_panel(self):
demoPanel = Frame(self)
demoPanel.pack(side=TOP, fill=BOTH, expand=Y)
# Create a canvas large enough to hold the wave. In fact, the wave
# sticks off both sides of the canvas to prevent visual glitches.
self.__canvas = Canvas(demoPanel, width=300, height=200, background='black')
self.__canvas.pack(padx=10, pady=10, expand=Y)
# Create a coordinates list for the wave. This code does a very sketchy
# job and relies on Tk's line smoothing to make things look better.
self.__waveCoords = []
for x in range(-10, 305, 5):
self.__waveCoords.extend((x, 100)) # straight line
self.__waveCoords.extend((305,0, 310, 200)) # frequency zig-zag
# Create a smoothed line using the wave coordinates we've just set
self.__canvas.create_line(self.__waveCoords, tags=('wave',),
width=1, fill='green', smooth=True)
self.__direction = 'left' # set the direction of wave
self._move() # start the animation
def _move(self):
# start the animation
self._basic_motion()
self._reverse_wave()
# repeat the animation every 10 milliseconds
self.after(10, self._move)
def _basic_motion(self):
# Basic motion handler.
# Advances the 'y' coordinates of the wave line
# one step in the currently active direction.
# get a copy of the current wave line coordinates
oc = list(self.__waveCoords)
oclen = len(oc)
for i in range(1, oclen, 2):
if self.__direction == 'left':
idx = i + 2
# at a boundary?
if idx > oclen: idx = 1
self.__waveCoords[i] = oc[idx]
else: # moving 'right'
idx = i - 2
# at a boundary?
if idx < 0: idx = oclen-1
self.__waveCoords[i] = oc[idx]
# redraw the wave line
self.__canvas.coords('wave', *self.__waveCoords)
def _reverse_wave(self):
# Oscillation handler. This detects whether to reverse the direction
# of the wave by checking to see if the peak of the wave (whose size
# we already know) has moved off the screen.
# get current wave line coordinates
wave = self.__canvas.coords('wave')
if wave[1] < 10: # first 'y' coord
self.__direction = 'right'
elif wave[-1] < 10: # last 'y' coord
self.__direction = 'left'
if __name__ == '__main__':
AnimatedWaveDemo().mainloop()
