import numpy as npy
import numpy.linalg as linalg
from pylab import figure, show
class Transformer:
def __init__(self, axes):
self.theta = 0
self.dtheta = 0.01
self.sx = 1.
self.sy = 1.
self.dx = 0.001
self.axes = axes
self.canvas = axes.figure.canvas
self.canvas.mpl_connect('button_press_event', self.press)
self.canvas.mpl_connect('button_release_event', self.release)
self.canvas.mpl_connect('motion_notify_event', self.move)
X1 = self.X1 = npy.matrix(npy.random.rand(2,2000))-0.5
x1 = X1[0].flat
y1 = X1[1].flat
x2 = X1[0].flat # no transformation yet
y2 = X1[1].flat
self.line1, self.line2 = ax.plot(x1, y1,'go', x2, y2, 'ro', markersize=2)
self.xlast = None
self.ylast = None
self.title = ax.set_title('drag the left or right mouse to stretch and rotate', fontweight='bold')
def press(self, event):
'mouse press, save the x and y locations'
self.xlast = event.xdata
self.ylast = event.ydata
def release(self, event):
'release the mouse'
self.xlast = None
self.ylast = None
self.draw()
def draw(self):
sx, sy, theta = self.sx, self.sy, self.theta
a = sx*npy.cos(theta)
b = -sx*npy.sin(theta)
c = sy*npy.sin(theta)
d = sy*npy.cos(theta)
M = npy.matrix([[a,b],[c,d]])
X2 = M*self.X1
x2 = X2[0].flat
y2 = X2[1].flat
self.line2.set_data(x2,y2)
self.canvas.draw()
def move(self, event):
if not event.inaxes: return # not over axes
if self.xlast is None: return # no initial data
if not event.button: return # no button press
dx = event.xdata - self.xlast
dy = event.ydata - self.ylast
if event.button==1:
self.theta += dx
elif event.button==3:
self.sx += dx
self.sy += dy
self.title.set_text('sx=%1.2f, sy=%1.2f, theta=%1.2f'%(self.sx, self.sy, self.theta))
self.draw()
self.xlast = event.xdata
self.ylast = event.ydata
from pylab import subplot, show
fig = figure()
ax = fig.add_subplot(111)
t = Transformer(ax)
show()
