codehwang · November 28, 2017 08:32 · Jul 13, 2015 · Jul 13, 2015
diff --git a/gistfile1.txt → gif.py b/gistfile1.txt → gif.py
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,136 @@
+# From https://github.com/wnyc/PIL/blob/master/Scripts/gifmaker.py
+#
+# The Python Imaging Library
+# $Id$
+#
+# convert sequence format to GIF animation
+#
+# history:
+#       97-01-03 fl     created
+#
+# Copyright (c) Secret Labs AB 1997.  All rights reserved.
+# Copyright (c) Fredrik Lundh 1997.
+#
+# See the README file for information on usage and redistribution.
+#
+
+#
+# For special purposes, you can import this module and call
+# the makedelta or compress functions yourself.  For example,
+# if you have an application that generates a sequence of
+# images, you can convert it to a GIF animation using some-
+# thing like the following code:
+#
+#       import Image
+#       import gifmaker
+#
+#       sequence = []
+#
+#       # generate sequence
+#       for i in range(100):
+#           im = <generate image i>
+#           sequence.append(im)
+#
+#       # write GIF animation
+#       fp = open("out.gif", "wb")
+#       gifmaker.makedelta(fp, sequence)
+#       fp.close()
+#
+# Alternatively, use an iterator to generate the sequence, and
+# write data directly to a socket.  Or something...
+#
+
+from PIL import Image, ImageChops
+import string
+
+from PIL.GifImagePlugin import getheader, getdata
+
+# --------------------------------------------------------------------
+# sequence iterator
+
+class image_sequence:
+    def __init__(self, im):
+        self.im = im
+    def __getitem__(self, ix):
+        try:
+            if ix:
+                self.im.seek(ix)
+            return self.im
+        except EOFError:
+            raise IndexError # end of sequence
+
+# --------------------------------------------------------------------
+# straightforward delta encoding
+
+def makedelta(fp, sequence):
+    """Convert list of image frames to a GIF animation file"""
+
+    frames = 0
+
+    previous = None
+
+    for im in sequence:
+
+        #
+        # FIXME: write graphics control block before each frame
+
+        if not previous:
+
+            # global header
+            for s in getheader(im) + getdata(im):
+                fp.write(s)
+
+        else:
+
+            # delta frame
+            delta = ImageChops.subtract_modulo(im, previous)
+
+            bbox = delta.getbbox()
+
+            if bbox:
+
+                # compress difference
+                for s in getdata(im.crop(bbox), offset = bbox[:2]):
+                    fp.write(s)
+
+            else:
+                # FIXME: what should we do in this case?
+                pass
+
+        previous = im.copy()
+
+        frames = frames + 1
+
+    fp.write(";")
+
+    return frames
+
+# --------------------------------------------------------------------
+# main hack
+
+def compress(infile, outfile):
+
+    # open input image, and force loading of first frame
+    im = Image.open(infile)
+    im.load()
+
+    # open output file
+    fp = open(outfile, "wb")
+
+    seq = image_sequence(im)
+
+    makedelta(fp, seq)
+
+    fp.close()
+
+
+if __name__ == "__main__":
+
+    import sys
+
+    if len(sys.argv) < 3:
+        print "GIFMAKER -- create GIF animations"
+        print "Usage: gifmaker infile outfile"
+        sys.exit(1)
+
+    compress(sys.argv[1], sys.argv[2])