Merge pull request #2103 from radarhere/append_images

Added append_images parameter to GIF saving

PIL/GifImagePlugin.py

@@ -351,34 +351,38 @@ def _save(im, fp, filename, save_all=False):
         previous = None
 
         first_frame = None
-        for im_frame in ImageSequence.Iterator(im):
+        append_images = im.encoderinfo.get("append_images", [])
-            im_frame = _convert_mode(im_frame)
+        for imSequence in [im]+append_images:
+            for im_frame in ImageSequence.Iterator(imSequence):
+                encoderinfo = im.encoderinfo.copy()
+                im_frame = _convert_mode(im_frame)
 
-            # To specify duration, add the time in milliseconds to getdata(),
+                # To specify duration, add the time in milliseconds to getdata(),
-            # e.g. getdata(im_frame, duration=1000)
+                # e.g. getdata(im_frame, duration=1000)
-            if not previous:
+                if not previous:
-                # global header
+                    # global header
-                first_frame = getheader(im_frame, palette, im.encoderinfo)[0]
+                    first_frame = getheader(im_frame, palette, encoderinfo)[0]
-                first_frame += getdata(im_frame, (0, 0), **im.encoderinfo)
+                    first_frame += getdata(im_frame, (0, 0), **encoderinfo)
-            else:
-                if first_frame:
-                    for s in first_frame:
-                        fp.write(s)
-                    first_frame = None
-
-                # delta frame
-                delta = ImageChops.subtract_modulo(im_frame, previous.copy())
-                bbox = delta.getbbox()
-
-                if bbox:
-                    # compress difference
-                    for s in getdata(im_frame.crop(bbox),
-                                     bbox[:2], **im.encoderinfo):
-                        fp.write(s)
                 else:
-                    # FIXME: what should we do in this case?
+                    if first_frame:
-                    pass
+                        for s in first_frame:
-            previous = im_frame
+                            fp.write(s)
+                        first_frame = None
+
+                    # delta frame
+                    delta = ImageChops.subtract_modulo(im_frame, previous.copy())
+                    bbox = delta.getbbox()
+
+                    if bbox:
+                        # compress difference
+                        encoderinfo['include_color_table'] = True
+                        for s in getdata(im_frame.crop(bbox),
+                                         bbox[:2], **encoderinfo):
+                            fp.write(s)
+                    else:
+                        # FIXME: what should we do in this case?
+                        pass
+                previous = im_frame
         if first_frame:
             save_all = False
     if not save_all:
@@ -455,7 +459,7 @@ def _get_local_header(fp, im, offset, flags):
         fp.write(b"!" +
                  o8(249) +                # extension intro
                  o8(4) +                  # length
-                 o8(transparency_flag) +  # transparency info present
+                 o8(transparency_flag) +  # packed fields
                  o16(duration) +          # duration
                  o8(transparency) +       # transparency index
                  o8(0))
@@ -476,13 +480,27 @@ def _get_local_header(fp, im, offset, flags):
                  o8(1) +
                  o16(number_of_loops) +   # number of loops
                  o8(0))
+    include_color_table = im.encoderinfo.get('include_color_table')
+    if include_color_table:
+        try:
+            palette = im.encoderinfo["palette"]
+        except KeyError:
+            palette = None
+        palette_bytes = _get_palette_bytes(im, palette, im.encoderinfo)[0]
+        color_table_size = _get_color_table_size(palette_bytes)
+        if color_table_size:
+            flags = flags | 128               # local color table flag
+            flags = flags | color_table_size
+
     fp.write(b"," +
              o16(offset[0]) +             # offset
              o16(offset[1]) +
              o16(im.size[0]) +            # size
              o16(im.size[1]) +
-             o8(flags) +                  # flags
+             o8(flags))                   # flags
-             o8(8))                       # bits
+    if include_color_table and color_table_size:
+        fp.write(_get_header_palette(palette_bytes))
+    fp.write(o8(8))                       # bits
 
 
 def _save_netpbm(im, fp, filename):
@@ -550,31 +568,25 @@ def _get_used_palette_colors(im):
 
     return used_palette_colors
 
+def _get_color_table_size(palette_bytes):
+    # calculate the palette size for the header
+    import math
+    color_table_size = int(math.ceil(math.log(len(palette_bytes)//3, 2)))-1
+    if color_table_size < 0:
+        color_table_size = 0
+    return color_table_size
 
-def getheader(im, palette=None, info=None):
+def _get_header_palette(palette_bytes):
-    """Return a list of strings representing a GIF header"""
+    color_table_size = _get_color_table_size(palette_bytes)
 
-    # Header Block
+    # add the missing amount of bytes
-    # http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
+    # the palette has to be 2<<n in size
-
+    actual_target_size_diff = (2 << color_table_size) - len(palette_bytes)//3
-    version = b"87a"
+    if actual_target_size_diff > 0:
-    for extensionKey in ["transparency", "duration", "loop", "comment"]:
+        palette_bytes += o8(0) * 3 * actual_target_size_diff
-        if info and extensionKey in info:
+    return palette_bytes
-            if ((extensionKey == "duration" and info[extensionKey] == 0) or
-                (extensionKey == "comment" and not (1 <= len(info[extensionKey]) <= 255))):
-                continue
-            version = b"89a"
-            break
-    else:
-        if im.info.get("version") == "89a":
-            version = b"89a"
-
-    header = [
-        b"GIF"+version +        # signature + version
-        o16(im.size[0]) +       # canvas width
-        o16(im.size[1])         # canvas height
-    ]
 
+def _get_palette_bytes(im, palette, info):
     if im.mode == "P":
         if palette and isinstance(palette, bytes):
             source_palette = palette[:768]
@@ -617,15 +629,38 @@ def getheader(im, palette=None, info=None):
 
     if not palette_bytes:
         palette_bytes = source_palette
+    return palette_bytes, used_palette_colors
+
+def getheader(im, palette=None, info=None):
+    """Return a list of strings representing a GIF header"""
+
+    # Header Block
+    # http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
+
+    version = b"87a"
+    for extensionKey in ["transparency", "duration", "loop", "comment"]:
+        if info and extensionKey in info:
+            if ((extensionKey == "duration" and info[extensionKey] == 0) or
+                (extensionKey == "comment" and not (1 <= len(info[extensionKey]) <= 255))):
+                continue
+            version = b"89a"
+            break
+    else:
+        if im.info.get("version") == "89a":
+            version = b"89a"
+
+    header = [
+        b"GIF"+version +        # signature + version
+        o16(im.size[0]) +       # canvas width
+        o16(im.size[1])         # canvas height
+    ]
+
+    palette_bytes, used_palette_colors = _get_palette_bytes(im, palette, info)
 
     # Logical Screen Descriptor
-    # calculate the palette size for the header
+    color_table_size = _get_color_table_size(palette_bytes)
-    import math
-    color_table_size = int(math.ceil(math.log(len(palette_bytes)//3, 2)))-1
-    if color_table_size < 0:
-        color_table_size = 0
     # size of global color table + global color table flag
-    header.append(o8(color_table_size + 128))
+    header.append(o8(color_table_size + 128))  # packed fields
     # background + reserved/aspect
     if info and "background" in info:
         background = info["background"]
@@ -640,14 +675,8 @@ def getheader(im, palette=None, info=None):
     header.append(o8(background) + o8(0))
     # end of Logical Screen Descriptor
 
-    # add the missing amount of bytes
-    # the palette has to be 2<<n in size
-    actual_target_size_diff = (2 << color_table_size) - len(palette_bytes)//3
-    if actual_target_size_diff > 0:
-        palette_bytes += o8(0) * 3 * actual_target_size_diff
-
     # Header + Logical Screen Descriptor + Global Color Table
-    header.append(palette_bytes)
+    header.append(_get_header_palette(palette_bytes))
     return header, used_palette_colors
 
 

Tests/test_file_gif.py

@@ -306,6 +306,24 @@ class TestFileGif(PillowTestCase):
         reread = Image.open(out)
         self.assertEqual(reread.info["version"], b"GIF87a")
 
+    def test_append_images(self):
+        out = self.tempfile('temp.gif')
+
+        # Test appending single frame images
+        im = Image.new('RGB', (100, 100), '#f00')
+        ims = [Image.new('RGB', (100, 100), color) for color in ['#0f0', '#00f']]
+        im.save(out, save_all=True, append_images=ims)
+
+        reread = Image.open(out)
+        self.assertEqual(reread.n_frames, 3)
+
+        # Tests appending single and multiple frame images
+        im = Image.open("Tests/images/dispose_none.gif")
+        ims = [Image.open("Tests/images/dispose_prev.gif")]
+        im.save(out, save_all=True, append_images=ims)
+
+        reread = Image.open(out)
+        self.assertEqual(reread.n_frames, 10)
 
 if __name__ == '__main__':
     unittest.main()

docs/handbook/image-file-formats.rst

@@ -103,7 +103,9 @@ Saving sequences
 
 When calling :py:meth:`~PIL.Image.Image.save`, if a multiframe image is used,
 by default only the first frame will be saved. To save all frames, the
-``save_all`` parameter must be present and set to ``True``.
+``save_all`` parameter must be present and set to ``True``. To append
+additional frames when saving, the ``append_images`` parameter can be set to a
+list of images containing the extra frames.
 
 If present, the ``loop`` parameter can be used to set the number of times
 the GIF should loop, and the ``duration`` parameter can set the number of