def _test_png_predictors(self, columns, encoded_data, pixel_data): obj = EncodedObject(encoded_data, Filter.Uncompressed, columns = columns, predictor = Predictor.PNGPredictionOptimum) obj_decode = obj.decode() self.assertEqual(len(obj_decode), len(pixel_data)) for line_offset in range(0, len(pixel_data), columns): self.assertEqual(obj_decode[line_offset : line_offset + columns], pixel_data[line_offset : line_offset + columns], "Row %d" % (line_offset // columns)) self.assertEqual(obj_decode, pixel_data)
def _encode_image(cls, image_filename, lossless):
if lossless:
img = PnmPicture.read_file(image_filename)
if img.img_format == PnmPictureFormat.Bitmap:
# PDFs use exactly inverted syntax for 1-bit images
img.invert()
imgdata = EncodedObject.create(img.data)
(colorspace, bits_per_component) = {
PnmPictureFormat.Bitmap: (PDFImageColorSpace.DeviceGray, 1),
PnmPictureFormat.Graymap: (PDFImageColorSpace.DeviceGray, 8),
PnmPictureFormat.Pixmap: (PDFImageColorSpace.DeviceRGB, 8),
}[img.img_format]
width = img.width
height = img.height
else:
with open(image_filename, "rb") as f:
imgdata = EncodedObject(encoded_data=f.read(),
filtering=Filter.DCTDecode)
(width, height, colorspace,
bits_per_component) = cls._get_image_geometry(image_filename)
colorspace = {
"Gray": PDFImageColorSpace.DeviceGray,
"sRGB": PDFImageColorSpace.DeviceRGB,
}[colorspace]
return PDFImage(width=width,
height=height,
colorspace=colorspace,
bits_per_component=bits_per_component,
imgdata=imgdata,
inverted=False)
def test_flate_decompress(self):
compressed_data = bytes.fromhex(
"78 9c 73 cb cf 4f 4a 2c 02 00 07 eb 02 5a")
obj = EncodedObject(compressed_data, Filter.FlateDecode)
self.assertEqual(obj.decode(), b"Foobar")
def test_no_decompress(self):
uncompressed_data = b"Foobar"
obj = EncodedObject(uncompressed_data, Filter.Uncompressed)
self.assertEqual(obj.decode(), b"Foobar")
def put_image(self, pdfimage):
if pdfimage.image_format not in [ "JPEG", "RGB", "GRAY" ]:
raise UnsupportedError("PDF can only handle JPEG, RGB or GRAY image formats, but %s was supplied." % (pdfimage.image_format))
custom_metadata = {
"resolution_dpi": list(pdfimage.resolution_dpi),
"comment": pdfimage.comment,
}
image = self.pdf.new_object({
PDFName("/Type"): PDFName("/XObject"),
PDFName("/Subtype"): PDFName("/Image"),
PDFName("/Interpolate"): True,
PDFName("/Width"): pdfimage.dimensions.width,
PDFName("/Height"): pdfimage.dimensions.height,
PDFName("/CustomMetadata"): PDFString(json.dumps(custom_metadata)),
})
if pdfimage.image_format == "JPEG":
image.set_stream(EncodedObject(encoded_data = pdfimage.data, filtering = Filter.DCTDecode))
elif pdfimage.image_format in [ "RGB", "GRAY" ]:
image.set_stream(EncodedObject.create(pdfimage.data, compress = True))
else:
raise NotImplementedError(pdfimage.image_format)
if pdfimage.pixel_format == PixelFormat.RGB:
image.content[PDFName("/ColorSpace")] = PDFName("/DeviceRGB")
image.content[PDFName("/BitsPerComponent")] = 8
elif pdfimage.pixel_format == PixelFormat.Grayscale:
image.content[PDFName("/ColorSpace")] = PDFName("/DeviceGray")
image.content[PDFName("/BitsPerComponent")] = 8
elif pdfimage.pixel_format == PixelFormat.BlackWhite:
image.content[PDFName("/ColorSpace")] = PDFName("/DeviceGray")
image.content[PDFName("/BitsPerComponent")] = 1
else:
raise NotImplementedError(pdfimage.pixel_format)
image_extents_mm = pdfimage.extents_mm
image_scale_x = self.printable_area_mm.width / image_extents_mm.width
image_scale_y = self.printable_area_mm.height / image_extents_mm.height
image_scalar = min(image_scale_x, image_scale_y)
if image_scalar > 1:
# Never enlarge
image_scalar = 1
printed_size_mm = image_extents_mm * image_scalar
page_dimensions_mm = self._hl_page.extents_mm
offset_mm = (page_dimensions_mm - printed_size_mm) / 2
offset_dots = offset_mm * 72 / 25.4
printed_size_dots = printed_size_mm * 72 / 25.4
params = {
"xoffset": offset_dots.width,
"yoffset": offset_dots.height,
"xscalar": printed_size_dots.width,
"yscalar": printed_size_dots.height,
}
self._hl_page.append_stream(textwrap.dedent("""\
%(xscalar)f 0 0 %(yscalar)f %(xoffset)f %(yoffset)f cm
/Img Do
""" % (params)))
page_obj = self._hl_page.page_obj
if not PDFName("/Resources") in page_obj.content:
page_obj.content[PDFName("/Resources")] = { }
if not PDFName("/XObject") in page_obj.content[PDFName("/Resources")]:
page_obj.content[PDFName("/Resources")][PDFName("/XObject")] = { }
page_obj.content[PDFName("/Resources")][PDFName("/XObject")][PDFName("/Img")] = image.xref