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Annotation of /fract/julia3.cgi

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Revision 1.3 - (hide annotations)
Sun Feb 25 22:54:15 2001 UTC (23 years, 8 months ago) by masse
Branch: MAIN
CVS Tags: HEAD
Changes since 1.2: +30 -47 lines
Extracted function drawrect from julia.cgi to Drawrect.py .
To use drawrect you now have to include function pointers to the
functions plot and fillrect in the arguments of drawrect .

1 teddy 1.1 #!/usr/bin/python
2    
3 masse 1.3 import sys
4    
5     sys.stderr = sys.stdout
6     #print "Content-Type: text/plain"
7     #print
8    
9     import cgi, Image, ImageDraw
10 teddy 1.1 from string import atoi
11 masse 1.3 from Drawrect import drawrect
12    
13 teddy 1.1
14     form= cgi.FieldStorage()
15    
16 teddy 1.2 # Image size
17     if form.has_key('width'):
18     width=atoi(form['width'].value)
19     else:
20     width= 570
21     if form.has_key('height'):
22     height=atoi(form['height'].value)
23     else:
24     height= 570
25    
26 teddy 1.1 xmax, ymax = width-1, height-1 # Coordinate maximums
27    
28     inx=max(0, min(atoi(form['image.x'].value), xmax))
29     iny=max(0, min(atoi(form['image.y'].value), ymax))
30     debug= form.has_key('debug')
31    
32     if form.has_key('iter'):
33     maxiter=atoi(form['iter'].value)
34     else:
35     maxiter= 270
36    
37     c1, c2 = (-2+2j), (2-2j) # Corner coordinates
38    
39     # Force c1 to be upper left and c2 to be lower right
40     c1, c2= complex(min(c1.real, c2.real), max(c1.imag, c2.imag)), \
41     complex(max(c1.real, c2.real), min(c1.imag, c2.imag))
42    
43     def constant(x, y):
44     creal= (float(x)/xmax)*(c2.real - c1.real)+c1.real
45     cimag= (float(y)/ymax)*(c2.imag - c1.imag)+c1.imag
46     return complex(creal, cimag)
47    
48     c= constant(inx, iny) # Julia set coordinate
49    
50     julia= Image.new("L", (width, height))
51     draw= ImageDraw.Draw(julia)
52    
53     def plot(x, y):
54     z= constant(x, y)
55     i= 0
56     color= julia.getpixel((x, y))
57     if color<>0:
58     return color
59     while i<maxiter and abs(z)<2:
60     z= z**2+c
61     i= i+1
62     color= 16*i%256
63     if i>=maxiter or color==0:
64     if debug:
65     color= 255
66     else:
67     color= 1
68     try:
69     julia.putpixel((x, y), color)
70     if yorig >= 0: # The x axis is visible on image
71     ym= 2*yorig-y # ym is y mirrored over yorig
72     xm= 2*xorig-x
73     if ym >= 0 and ym <= ymax and xm>=0 and xm<=xmax:
74     # ym is on the image
75     julia.putpixel((xm-1, ym), color)
76     except IndexError, the_error:
77     print "coord", x, y, xm, ym
78     raise IndexError, the_error
79     return color
80    
81 masse 1.3
82    
83 teddy 1.1 # Initial default values
84     yfrom= 0
85     yto= ymax
86     yorig= -1 # The pixel coordinate of the x axis; negative means not on image
87     xorig= -1
88    
89 masse 1.3
90     def fillrect(x1, y1, x2, y2, color):
91     draw.rectangle([x1, y1, x2, y2], fill= color)
92     if yorig >= 0: # The x axis is visible on image
93     # mirror over yorig, but keep within image
94     y1m= max(0, min(2*yorig-y1, ymax))
95     y2m= max(0, min(2*yorig-y2, ymax))
96     x1m= max(0, min(2*xorig-x1, xmax))
97     x2m= max(0, min(2*xorig-x2, xmax))
98     draw.rectangle([x1m, y1m, x2m, y2m], fill= color)
99    
100    
101 teddy 1.1 # Check if we should do mirroring
102     if c1.imag > 0 and c2.imag < 0: # the x axis is visible
103     yorig= int((-c1.imag/(c2.imag-c1.imag))*height) # pixel pos. of x axis
104     if c1.imag < abs(c2.imag): # the x axis is closer to top than bottom
105     yfrom= yorig # Begin at x axis
106     else:
107     yto= yorig # End at x axis
108    
109     if c1.real < 0 and c2.real > 0:
110     xorig= int((-c1.real/(c2.real-c1.real))*height)
111    
112 masse 1.3 if not debug:
113     funcpoint= fillrect
114     else:
115     funcpoint= lambda x1, y1, x2, y2, color: x1+y1+x2+y2+color
116    
117     drawrect((0, yfrom), (xmax, yto), plot, funcpoint)
118 teddy 1.1
119     print "Content-type: image/png"
120     print
121     julia.save(sys.stdout, "PNG")
122 masse 1.3

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