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https://github.com/python-pillow/Pillow.git
synced 2024-12-25 17:36:18 +03:00
Added local color table for subsequent GIF frames
This commit is contained in:
Andrew Murray
parent
6e7553fb0f
commit
be7a191b6e
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@ -372,6 +372,7 @@ def _save(im, fp, filename, save_all=False):
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if bbox:
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# compress difference
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encoderinfo['include_color_table'] = True
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for s in getdata(im_frame.crop(bbox),
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bbox[:2], **im.encoderinfo):
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fp.write(s)
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@ -455,7 +456,7 @@ def _get_local_header(fp, im, offset, flags):
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fp.write(b"!" +
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o8(249) + # extension intro
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o8(4) + # length
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o8(transparency_flag) + # transparency info present
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o8(transparency_flag) + # packed fields
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o16(duration) + # duration
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o8(transparency) + # transparency index
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o8(0))
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@ -476,13 +477,27 @@ def _get_local_header(fp, im, offset, flags):
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o8(1) +
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o16(number_of_loops) + # number of loops
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o8(0))
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include_color_table = im.encoderinfo.get('include_color_table')
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if include_color_table:
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try:
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palette = im.encoderinfo["palette"]
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except KeyError:
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palette = None
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palette_bytes = _get_palette_bytes(im, palette, im.encoderinfo)[0]
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color_table_size = _get_color_table_size(palette_bytes)
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if color_table_size:
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flags = flags | 128 # local color table flag
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flags = flags | color_table_size
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fp.write(b"," +
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o16(offset[0]) + # offset
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o16(offset[1]) +
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o16(im.size[0]) + # size
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o16(im.size[1]) +
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o8(flags) + # flags
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o8(8)) # bits
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o8(flags)) # flags
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if include_color_table and color_table_size:
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fp.write(_get_header_palette(palette_bytes))
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fp.write(o8(8)) # bits
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def _save_netpbm(im, fp, filename):
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@ -550,31 +565,25 @@ def _get_used_palette_colors(im):
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return used_palette_colors
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def _get_color_table_size(palette_bytes):
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# calculate the palette size for the header
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import math
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color_table_size = int(math.ceil(math.log(len(palette_bytes)//3, 2)))-1
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if color_table_size < 0:
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color_table_size = 0
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return color_table_size
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def getheader(im, palette=None, info=None):
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"""Return a list of strings representing a GIF header"""
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def _get_header_palette(palette_bytes):
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color_table_size = _get_color_table_size(palette_bytes)
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# Header Block
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# http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
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version = b"87a"
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for extensionKey in ["transparency", "duration", "loop", "comment"]:
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if info and extensionKey in info:
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if ((extensionKey == "duration" and info[extensionKey] == 0) or
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(extensionKey == "comment" and not (1 <= len(info[extensionKey]) <= 255))):
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continue
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version = b"89a"
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break
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else:
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if im.info.get("version") == "89a":
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version = b"89a"
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header = [
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b"GIF"+version + # signature + version
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o16(im.size[0]) + # canvas width
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o16(im.size[1]) # canvas height
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]
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# add the missing amount of bytes
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# the palette has to be 2<<n in size
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actual_target_size_diff = (2 << color_table_size) - len(palette_bytes)//3
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if actual_target_size_diff > 0:
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palette_bytes += o8(0) * 3 * actual_target_size_diff
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return palette_bytes
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def _get_palette_bytes(im, palette, info):
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if im.mode == "P":
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if palette and isinstance(palette, bytes):
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source_palette = palette[:768]
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@ -617,15 +626,38 @@ def getheader(im, palette=None, info=None):
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if not palette_bytes:
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palette_bytes = source_palette
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return palette_bytes, used_palette_colors
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def getheader(im, palette=None, info=None):
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"""Return a list of strings representing a GIF header"""
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# Header Block
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# http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
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version = b"87a"
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for extensionKey in ["transparency", "duration", "loop", "comment"]:
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if info and extensionKey in info:
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if ((extensionKey == "duration" and info[extensionKey] == 0) or
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(extensionKey == "comment" and not (1 <= len(info[extensionKey]) <= 255))):
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continue
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version = b"89a"
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break
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else:
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if im.info.get("version") == "89a":
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version = b"89a"
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header = [
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b"GIF"+version + # signature + version
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o16(im.size[0]) + # canvas width
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o16(im.size[1]) # canvas height
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]
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palette_bytes, used_palette_colors = _get_palette_bytes(im, palette, info)
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# Logical Screen Descriptor
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# calculate the palette size for the header
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import math
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color_table_size = int(math.ceil(math.log(len(palette_bytes)//3, 2)))-1
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if color_table_size < 0:
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color_table_size = 0
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color_table_size = _get_color_table_size(palette_bytes)
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# size of global color table + global color table flag
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header.append(o8(color_table_size + 128))
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header.append(o8(color_table_size + 128)) # packed fields
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# background + reserved/aspect
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if info and "background" in info:
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background = info["background"]
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@ -640,14 +672,8 @@ def getheader(im, palette=None, info=None):
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header.append(o8(background) + o8(0))
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# end of Logical Screen Descriptor
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# add the missing amount of bytes
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# the palette has to be 2<<n in size
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actual_target_size_diff = (2 << color_table_size) - len(palette_bytes)//3
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if actual_target_size_diff > 0:
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palette_bytes += o8(0) * 3 * actual_target_size_diff
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# Header + Logical Screen Descriptor + Global Color Table
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header.append(palette_bytes)
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header.append(_get_header_palette(palette_bytes))
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return header, used_palette_colors
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