1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
|
#!/usr/bin/env python
"""
Test ImageSurface.get_data()
"""
import tempfile
import cairo
if not (cairo.HAS_IMAGE_SURFACE and cairo.HAS_PNG_FUNCTIONS):
raise SystemExit ('cairo was not compiled with ImageSurface and PNG support')
width, height = 128, 128
def create_surface(cformat, w, h):
"create black triangle on white background"
surface = cairo.ImageSurface(cformat, w, h)
ctx = cairo.Context(surface)
ctx.set_source_rgb(1, 1, 1) # white
ctx.set_operator(cairo.OPERATOR_SOURCE)
ctx.paint()
# Draw out the triangle using absolute coordinates
ctx.move_to(w/2, h/3)
ctx.line_to(2*w/3, 2*h/3)
ctx.rel_line_to(-1*w/3, 0)
ctx.close_path()
ctx.set_source_rgb(0, 0, 0) # black
ctx.set_line_width(15)
ctx.stroke()
return surface
def test_python_buffer():
"get_data() and modify data using Python"
surface = create_surface(cairo.FORMAT_ARGB32, width, height)
_, f1 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
surface.write_to_png(f1)
buf = surface.get_data()
stride = surface.get_stride()
for i in range(height):
offset = i * stride + 120
buf[offset] = b'\xFF'
buf[offset + 1] = b'\x00'
buf[offset + 2] = b'\x00'
_, f2 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
surface.write_to_png(f2)
print("""\
test_python_buffer:
original data: %s
modified data: %s
""" % (f1, f2))
def test_numpy_and_python_buffer():
"get_data() and modify data using numpy"
try:
import numpy
except:
print("numpy not installed")
return
surface = create_surface(cairo.FORMAT_ARGB32, width, height)
_, f1 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
surface.write_to_png(f1)
buf = surface.get_data()
a = numpy.ndarray(shape=(w,h,4), dtype=numpy.uint8, buffer=buf)
# draw a vertical line
a[:,40,0] = 255 # byte 0 is blue on little-endian systems
a[:,40,1] = 0
a[:,40,2] = 0
_, f2 = tempfile.mkstemp(prefix='pycairo_', suffix='.png')
surface.write_to_png(f2)
print("""\
test_numpy_and_python_buffer:
original data: %s
modified data: %s
""" % (f1, f2))
test_python_buffer()
test_numpy_and_python_buffer()
|
