def _handle_failed_image(idiff, src_img, pngr, img_fname):
"""Writes all the necessary images when an image comparison
failed."""
f_base, f_ext = os.path.splitext(img_fname)
# write out the difference file in full.
pngw = tvtk.PNGWriter(file_name=f_base + ".diff.png")
configure_input(pngw, idiff)
pngw.write()
# write the difference image scaled and gamma adjusted for the
# dashboard.
sz = pngr.output.dimensions
if sz[1] <= 250.0:
mag = 1.0
else:
mag = 250.0/sz[1]
shrink = tvtk.ImageResample(interpolate=1)
configure_input(shrink, idiff.output)
shrink.set_axis_magnification_factor(0, mag)
shrink.set_axis_magnification_factor(1, mag)
gamma = tvtk.ImageShiftScale(shift=0, scale=10)
configure_input(gamma, shrink)
jpegw = tvtk.JPEGWriter(file_name=f_base + ".diff.small.jpg",
quality=85)
configure_input(jpegw, gamma)
jpegw.write()
# write out the image that was generated.
pngw.trait_set(file_name=f_base + ".test.png")
configure_input(pngw, src_img)
pngw.write()
# write out a smaller version of the image that was generated.
configure_input(shrink, idiff.input)
jpegw.trait_set(file_name=f_base + ".test.small.jpg")
configure_input(jpegw, shrink)
jpegw.write()
# write out the valid image that matched.
configure_input(shrink, idiff.image)
jpegw.trait_set(file_name=f_base + ".small.jpg")
configure_input(jpegw, shrink)
jpegw.write()
def compare_image_with_saved_image(src_img,
img_fname,
threshold=10,
allow_resize=True):
"""Compares a source image (src_img, which is a tvtk.ImageData)
with the saved image file whose name is given in the second
argument. If the image file does not exist the image is generated
and stored. If not the source image is compared to that of the
figure. This function also handles multiple images and finds the
best matching image. If `allow_resize` is True then the images
are rescaled if they are not of the same size.
"""
f_base, f_ext = os.path.splitext(os.path.abspath(img_fname))
if not os.path.isfile(img_fname):
# generate the image
pngw = tvtk.PNGWriter(file_name=img_fname, input=src_img)
pngw.write()
if VERBOSE:
print "Creating baseline image '%s'." % img_fname
return
pngr = tvtk.PNGReader(file_name=img_fname)
pngr.update()
if allow_resize:
src_resample = tvtk.ImageResample(input=src_img,
interpolate=1,
interpolation_mode='cubic')
img_resample = tvtk.ImageResample(input=pngr.output,
interpolate=1,
interpolation_mode='cubic')
_set_scale(src_resample, img_resample)
idiff = tvtk.ImageDifference(input=src_resample.output,
image=img_resample.output)
else:
idiff = tvtk.ImageDifference(input=src_img, image=pngr.output)
idiff.update()
min_err = idiff.thresholded_error
img_err = min_err
best_img = img_fname
err_index = 0
count = 0
if min_err > threshold:
count = 1
test_failed = 1
err_index = -1
while 1: # keep trying images till we get the best match.
new_fname = f_base + "_%d.png" % count
if not os.path.exists(new_fname):
# no other image exists.
break
# since file exists check if it matches.
pngr.file_name = new_fname
pngr.update()
if allow_resize:
_set_scale(src_resample, img_resample)
idiff.update()
alt_err = idiff.thresholded_error
if alt_err < threshold:
# matched,
err_index = count
test_failed = 0
min_err = alt_err
img_err = alt_err
best_img = new_fname
break
else:
if alt_err < min_err:
# image is a better match.
err_index = count
min_err = alt_err
img_err = alt_err
best_img = new_fname
count = count + 1
# closes while loop.
if test_failed:
_handle_failed_image(idiff, src_img, pngr, best_img)
_print_image_error(img_err, err_index, f_base)
msg = "Failed image test: %f\n" % idiff.thresholded_error
raise AssertionError, msg
# output the image error even if a test passed
_print_image_success(img_err, err_index)