Add legacy pdf image extract option (#1225)

kindlecomicconverter/pdfjpgextract.py

@@ -0,0 +1,75 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2012-2014 Ciro Mattia Gonano <ciromattia@gmail.com>
+# Copyright (c) 2013-2019 Pawel Jastrzebski <pawelj@iosphe.re>
+#
+# Based upon the code snippet by Ned Batchelder
+# (http://nedbatchelder.com/blog/200712/extracting_jpgs_from_pdfs.html)
+#
+# Permission to use, copy, modify, and/or distribute this software for
+# any purpose with or without fee is hereby granted, provided that the
+# above copyright notice and this permission notice appear in all
+# copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+# WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+# AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+# DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
+# OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+# TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+# PERFORMANCE OF THIS SOFTWARE.
+#
+
+import os
+
+# skip stray images a few pixels in size in some PDFs
+# typical images are many thousands in length
+# https://github.com/ciromattia/kcc/pull/546
+STRAY_IMAGE_LENGTH_THRESHOLD = 300
+
+
+class PdfJpgExtract:
+    def __init__(self, fname, fullPath):
+        self.fname = fname
+        self.path = fullPath
+
+    def getPath(self):
+        return self.path
+
+    def extract(self):
+        pdf = open(self.fname, "rb").read()
+        startmark = b"\xff\xd8"
+        startfix = 0
+        endmark = b"\xff\xd9"
+        endfix = 2
+        i = 0
+        njpg = 0
+        while True:
+            istream = pdf.find(b"stream", i)
+            if istream < 0:
+                break
+            istart = pdf.find(startmark, istream, istream + 20)
+            if istart < 0:
+                i = istream + 20
+                continue
+            iend = pdf.find(b"endstream", istart)
+            if iend < 0:
+                raise Exception("Didn't find end of stream!")
+            iend = pdf.find(endmark, iend - 20)
+            if iend < 0:
+                raise Exception("Didn't find end of JPG!")
+            istart += startfix
+            iend += endfix
+            i = iend
+
+            if iend - istart < STRAY_IMAGE_LENGTH_THRESHOLD:
+                continue
+
+            jpg = pdf[istart:iend]
+            jpgfile = open(os.path.join(self.path, "jpg%d.jpg" % njpg), "wb")
+            jpgfile.write(jpg)
+            jpgfile.close()
+            njpg += 1
+
+        return njpg