def __init__(self, wdw, r, c):
"""
Determines layout of the canvas,
number of rows and colums is r and c.
"""
wdw.title('a 4-bar mechanism')
self.fbr = FourBar()
self.rows = r
self.cols = c
self.ox = c/3
self.oy = 3*r/4
# print "A =" , (self.ox, self.oy)
self.togo = False
# the canvas and start, stop, and clear buttons
self.c = Canvas(wdw, width=self.cols, height=self.rows, bg='green')
self.c.grid(row=1, column=2, columnspan=2)
self.startbut = Button(wdw, text='start', command = self.start)
self.startbut.grid(row=3, column=2, sticky=W+E)
self.stopbut = Button(wdw, text='stop', command = self.stop)
self.stopbut.grid(row=3, column=3, sticky=W+E)
self.clearbut = Button(wdw, text='clear', command = self.clear)
self.clearbut.grid(row=3, column=4, columnspan=3, sticky=W+E)
# the length of the crank
self.crank_lbl = Label(wdw, text='crank', justify=LEFT)
self.crank_lbl.grid(row=0, column=0)
self.crank_bar = IntVar()
self.L = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.crank_bar, command=self.draw_mechanism)
self.L.set(self.fbr.crank)
self.L.grid(row=1, column=0)
# the angle that drives the crank
self.angle_lbl = Label(wdw, text='angle', justify=LEFT)
self.angle_lbl.grid(row=0, column=1)
self.angle = DoubleVar()
self.t = Scale(wdw, orient='vertical', from_=0, to=6.30, \
tickinterval=0.30, resolution=0.01, length=self.rows, \
variable=self.angle, command=self.draw_mechanism)
self.t.grid(row=1, column=1)
self.angle.set(self.fbr.angle)
# the bar at the right
self.right_bar_lbl = Label(wdw, text='right bar', justify=LEFT)
self.right_bar_lbl.grid(row=0, column=4)
self.right_bar = IntVar()
self.r = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.right_bar, command=self.draw_mechanism)
self.r.grid(row=1, column=4)
self.right_bar.set(self.fbr.right)
# the top bar attached to the crank
self.top_bar_lbl = Label(wdw, text='top bar', justify=LEFT)
self.top_bar_lbl.grid(row=0, column=5)
self.r_top_bar = IntVar()
self.R = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.r_top_bar, command=self.draw_mechanism)
self.R.grid(row=1, column=5)
self.r_top_bar.set(self.fbr.top)
# the scale for the coupler bar
self.coupler_bar_lbl = Label(wdw, text='coupler', justify=LEFT)
self.coupler_bar_lbl.grid(row=0, column=6)
self.coupler_bar = IntVar()
self.cpl = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.coupler_bar, command=self.draw_mechanism)
self.cpl.grid(row=1, column=6)
self.coupler_bar.set(self.fbr.coupler)
# the horizontal bottom bar
self.flat_lbl = Label(wdw, text='right joint', justify=RIGHT)
self.flat_lbl.grid(row=2, column=1)
self.flat = IntVar()
self.f = Scale(wdw, orient='horizontal', from_=0, to=self.rows/2, \
tickinterval=50, resolution=1, length=self.cols, \
variable=self.flat, command=self.draw_mechanism)
self.f.grid(row=2, column=2, columnspan=2)
self.flat.set(self.fbr.flat)
# coordinates of the coupler point appear on top
self.ex = Entry(wdw) # for x value
self.ex.grid(row=0, column=2)
self.ex.insert(INSERT, "x = ")
self.ey = Entry(wdw) # for y value
self.ey.grid(row=0, column=3)
self.ey.insert(INSERT,"y = ")
# check button for drawing of coupler curve
self.curve = IntVar()
self.cb = Checkbutton(wdw, text='coupler', \
variable=self.curve, onvalue=1, offvalue=0)
self.curve.set(1)
self.cb.grid(row=3, column=0)
# draw the mechanism on canvas
self.draw_mechanism(0)
class FourBarGUI(object):
"""
GUI to model a 4-bar mechanism.
"""
def __init__(self, wdw, r, c):
"""
Determines layout of the canvas,
number of rows and colums is r and c.
"""
wdw.title('a 4-bar mechanism')
self.fbr = FourBar()
self.rows = r
self.cols = c
self.ox = c/3
self.oy = 3*r/4
# print "A =" , (self.ox, self.oy)
self.togo = False
# the canvas and start, stop, and clear buttons
self.c = Canvas(wdw, width=self.cols, height=self.rows, bg='green')
self.c.grid(row=1, column=2, columnspan=2)
self.startbut = Button(wdw, text='start', command = self.start)
self.startbut.grid(row=3, column=2, sticky=W+E)
self.stopbut = Button(wdw, text='stop', command = self.stop)
self.stopbut.grid(row=3, column=3, sticky=W+E)
self.clearbut = Button(wdw, text='clear', command = self.clear)
self.clearbut.grid(row=3, column=4, columnspan=3, sticky=W+E)
# the length of the crank
self.crank_lbl = Label(wdw, text='crank', justify=LEFT)
self.crank_lbl.grid(row=0, column=0)
self.crank_bar = IntVar()
self.L = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.crank_bar, command=self.draw_mechanism)
self.L.set(self.fbr.crank)
self.L.grid(row=1, column=0)
# the angle that drives the crank
self.angle_lbl = Label(wdw, text='angle', justify=LEFT)
self.angle_lbl.grid(row=0, column=1)
self.angle = DoubleVar()
self.t = Scale(wdw, orient='vertical', from_=0, to=6.30, \
tickinterval=0.30, resolution=0.01, length=self.rows, \
variable=self.angle, command=self.draw_mechanism)
self.t.grid(row=1, column=1)
self.angle.set(self.fbr.angle)
# the bar at the right
self.right_bar_lbl = Label(wdw, text='right bar', justify=LEFT)
self.right_bar_lbl.grid(row=0, column=4)
self.right_bar = IntVar()
self.r = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.right_bar, command=self.draw_mechanism)
self.r.grid(row=1, column=4)
self.right_bar.set(self.fbr.right)
# the top bar attached to the crank
self.top_bar_lbl = Label(wdw, text='top bar', justify=LEFT)
self.top_bar_lbl.grid(row=0, column=5)
self.r_top_bar = IntVar()
self.R = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.r_top_bar, command=self.draw_mechanism)
self.R.grid(row=1, column=5)
self.r_top_bar.set(self.fbr.top)
# the scale for the coupler bar
self.coupler_bar_lbl = Label(wdw, text='coupler', justify=LEFT)
self.coupler_bar_lbl.grid(row=0, column=6)
self.coupler_bar = IntVar()
self.cpl = Scale(wdw, orient='vertical', from_=0, to=self.rows/2, \
tickinterval=20, resolution=1, length=self.rows, \
variable=self.coupler_bar, command=self.draw_mechanism)
self.cpl.grid(row=1, column=6)
self.coupler_bar.set(self.fbr.coupler)
# the horizontal bottom bar
self.flat_lbl = Label(wdw, text='right joint', justify=RIGHT)
self.flat_lbl.grid(row=2, column=1)
self.flat = IntVar()
self.f = Scale(wdw, orient='horizontal', from_=0, to=self.rows/2, \
tickinterval=50, resolution=1, length=self.cols, \
variable=self.flat, command=self.draw_mechanism)
self.f.grid(row=2, column=2, columnspan=2)
self.flat.set(self.fbr.flat)
# coordinates of the coupler point appear on top
self.ex = Entry(wdw) # for x value
self.ex.grid(row=0, column=2)
self.ex.insert(INSERT, "x = ")
self.ey = Entry(wdw) # for y value
self.ey.grid(row=0, column=3)
self.ey.insert(INSERT,"y = ")
# check button for drawing of coupler curve
self.curve = IntVar()
self.cb = Checkbutton(wdw, text='coupler', \
variable=self.curve, onvalue=1, offvalue=0)
self.curve.set(1)
self.cb.grid(row=3, column=0)
# draw the mechanism on canvas
self.draw_mechanism(0)
def update_values(self):
"""
Takes all values of the scales and updates
the data attributes of self.fbr.
"""
self.fbr.flat = self.flat.get()
self.fbr.crank = self.crank_bar.get()
self.fbr.top = self.r_top_bar.get()
self.fbr.right = self.right_bar.get()
self.fbr.coupler = self.coupler_bar.get()
self.fbr.angle = self.angle.get()
#self.fbr.print_joints()
def draw_coupler_point(self, p):
"""
Draws coupler point with coordinates in p
if the curve checkbox is on.
Note that the previous values for the coordinates
of the coupler point are stored in the entry fields.
"""
if self.curve.get() == 1:
px = self.ox + p[0]
py = self.oy - p[1]
eqx = self.ex.get()
Lx = eqx.split('=')
if Lx[1] == ' ':
qx = 0.0
else:
qx = float(Lx[1])
eqy = self.ey.get()
Ly = eqy.split('=')
if Ly[1] == ' ':
qy = 0.0
else:
qy = float(Ly[1])
if (qx != 0.0) and (qy != 0.0):
qx = self.ox + qx
qy = self.oy - qy
self.c.create_line(qx, qy, px, py, width=1)
def fill_entries(self, p):
"""
Fills the entry fields with the coordinates
of the coupler point in p.
"""
sx = 'x = %f' % p[0]
sy = 'y = %f' % p[1]
self.ex.delete(0, END)
self.ex.insert(INSERT, sx)
self.ey.delete(0, END)
self.ey.insert(INSERT, sy)
def draw_link(self, p, q, s):
"""
Draws the link from point with coordinates in p
to the point with coordinates in q, using s as tag.
"""
self.c.delete(s)
px = self.ox + p[0]
py = self.oy - p[1]
qx = self.ox + q[0]
qy = self.oy - q[1]
self.c.create_line(px, py, qx, qy, width=2, tags=s)
def draw_mechanism(self, v):
"""
Fills the canvas with the current model
of the planar 4-bar mechanism.
Because this command is called by the sliders,
the argument v is needed but not used.
"""
self.update_values()
L = self.fbr.joints()
for i in range(0, len(L)):
p = L[i]
px = self.ox + p[0]
py = self.oy - p[1]
sj = 'joint%d' % i
self.c.delete(sj)
self.c.create_oval(px-6, py-6, px+6, py+6, width=1, \
outline='black', fill='red', tags=sj)
self.draw_link(L[0], L[2], 'link0')
self.draw_link(L[1], L[3], 'link1')
self.draw_link(L[2], L[3], 'link2')
self.draw_link(L[2], L[4], 'link3')
self.draw_coupler_point(L[4])
self.fill_entries(L[4])
def start(self):
"""
Starts the animation, adding 0.01 to angle.
"""
self.togo = True
while self.togo:
theta = self.angle.get()
theta = theta + 0.01
if theta > 6.28:
theta = 0
self.angle.set(theta)
self.draw_mechanism(0)
self.c.update()
def stop(self):
"""
Stops the animation.
"""
self.togo = False
def clear(self):
"""
Clears the canvas.
"""
self.c.delete(ALL)
