from . import Image, ImageFile
try:
from . import _webp
SUPPORTED = True
except ImportError:
SUPPORTED = False
from io import BytesIO
_VALID_WEBP_MODES = {
"RGBX": True,
"RGBA": True,
"RGB": True,
}
_VALID_WEBP_LEGACY_MODES = {
"RGB": True,
"RGBA": True,
}
_VP8_MODES_BY_IDENTIFIER = {
b"VP8 ": "RGB",
b"VP8X": "RGBA",
b"VP8L": "RGBA", # lossless
}
def _accept(prefix):
is_riff_file_format = prefix[:4] == b"RIFF"
is_webp_file = prefix[8:12] == b"WEBP"
is_valid_vp8_mode = prefix[12:16] in _VP8_MODES_BY_IDENTIFIER
if is_riff_file_format and is_webp_file and is_valid_vp8_mode:
if not SUPPORTED:
return "image file could not be identified " \
"because WEBP support not installed"
return True
[文档]class WebPImageFile(ImageFile.ImageFile):
format = "WEBP"
format_description = "WebP image"
def _open(self):
if not _webp.HAVE_WEBPANIM:
# Legacy mode
data, width, height, self.mode, icc_profile, exif = \
_webp.WebPDecode(self.fp.read())
if icc_profile:
self.info["icc_profile"] = icc_profile
if exif:
self.info["exif"] = exif
self._size = width, height
self.fp = BytesIO(data)
self.tile = [("raw", (0, 0) + self.size, 0, self.mode)]
self._n_frames = 1
return
# Use the newer AnimDecoder API to parse the (possibly) animated file,
# and access muxed chunks like ICC/EXIF/XMP.
self._decoder = _webp.WebPAnimDecoder(self.fp.read())
# Get info from decoder
width, height, loop_count, bgcolor, frame_count, mode = \
self._decoder.get_info()
self._size = width, height
self.info["loop"] = loop_count
bg_a, bg_r, bg_g, bg_b = \
(bgcolor >> 24) & 0xFF, \
(bgcolor >> 16) & 0xFF, \
(bgcolor >> 8) & 0xFF, \
bgcolor & 0xFF
self.info["background"] = (bg_r, bg_g, bg_b, bg_a)
self._n_frames = frame_count
self.mode = 'RGB' if mode == 'RGBX' else mode
self.rawmode = mode
self.tile = []
# Attempt to read ICC / EXIF / XMP chunks from file
icc_profile = self._decoder.get_chunk("ICCP")
exif = self._decoder.get_chunk("EXIF")
xmp = self._decoder.get_chunk("XMP ")
if icc_profile:
self.info["icc_profile"] = icc_profile
if exif:
self.info["exif"] = exif
if xmp:
self.info["xmp"] = xmp
# Initialize seek state
self._reset(reset=False)
self.seek(0)
def _getexif(self):
from .JpegImagePlugin import _getexif
return _getexif(self)
@property
def n_frames(self):
return self._n_frames
@property
def is_animated(self):
return self._n_frames > 1
[文档] def seek(self, frame):
if not _webp.HAVE_WEBPANIM:
return super(WebPImageFile, self).seek(frame)
# Perform some simple checks first
if frame >= self._n_frames:
raise EOFError("attempted to seek beyond end of sequence")
if frame < 0:
raise EOFError("negative frame index is not valid")
# Set logical frame to requested position
self.__logical_frame = frame
def _reset(self, reset=True):
if reset:
self._decoder.reset()
self.__physical_frame = 0
self.__loaded = -1
self.__timestamp = 0
def _get_next(self):
# Get next frame
ret = self._decoder.get_next()
self.__physical_frame += 1
# Check if an error occurred
if ret is None:
self._reset() # Reset just to be safe
self.seek(0)
raise EOFError("failed to decode next frame in WebP file")
# Compute duration
data, timestamp = ret
duration = timestamp - self.__timestamp
self.__timestamp = timestamp
# libwebp gives frame end, adjust to start of frame
timestamp -= duration
return data, timestamp, duration
def _seek(self, frame):
if self.__physical_frame == frame:
return # Nothing to do
if frame < self.__physical_frame:
self._reset() # Rewind to beginning
while self.__physical_frame < frame:
self._get_next() # Advance to the requested frame
[文档] def load(self):
if _webp.HAVE_WEBPANIM:
if self.__loaded != self.__logical_frame:
self._seek(self.__logical_frame)
# We need to load the image data for this frame
data, timestamp, duration = self._get_next()
self.info["timestamp"] = timestamp
self.info["duration"] = duration
self.__loaded = self.__logical_frame
# Set tile
if self.fp and self._exclusive_fp:
self.fp.close()
self.fp = BytesIO(data)
self.tile = [("raw", (0, 0) + self.size, 0, self.rawmode)]
return super(WebPImageFile, self).load()
[文档] def tell(self):
if not _webp.HAVE_WEBPANIM:
return super(WebPImageFile, self).tell()
return self.__logical_frame
def _save_all(im, fp, filename):
encoderinfo = im.encoderinfo.copy()
append_images = list(encoderinfo.get("append_images", []))
# If total frame count is 1, then save using the legacy API, which
# will preserve non-alpha modes
total = 0
for ims in [im]+append_images:
total += 1 if not hasattr(ims, "n_frames") else ims.n_frames
if total == 1:
_save(im, fp, filename)
return
background = (0, 0, 0, 0)
if "background" in encoderinfo:
background = encoderinfo["background"]
elif "background" in im.info:
background = im.info["background"]
if isinstance(background, int):
# GifImagePlugin stores a global color table index in
# info["background"]. So it must be converted to an RGBA value
palette = im.getpalette()
if palette:
r, g, b = palette[background*3:(background+1)*3]
background = (r, g, b, 0)
duration = im.encoderinfo.get("duration", 0)
loop = im.encoderinfo.get("loop", 0)
minimize_size = im.encoderinfo.get("minimize_size", False)
kmin = im.encoderinfo.get("kmin", None)
kmax = im.encoderinfo.get("kmax", None)
allow_mixed = im.encoderinfo.get("allow_mixed", False)
verbose = False
lossless = im.encoderinfo.get("lossless", False)
quality = im.encoderinfo.get("quality", 80)
method = im.encoderinfo.get("method", 0)
icc_profile = im.encoderinfo.get("icc_profile", "")
exif = im.encoderinfo.get("exif", "")
xmp = im.encoderinfo.get("xmp", "")
if allow_mixed:
lossless = False
# Sensible keyframe defaults are from gif2webp.c script
if kmin is None:
kmin = 9 if lossless else 3
if kmax is None:
kmax = 17 if lossless else 5
# Validate background color
if (not isinstance(background, (list, tuple)) or len(background) != 4 or
not all(v >= 0 and v < 256 for v in background)):
raise IOError("Background color is not an RGBA tuple clamped "
"to (0-255): %s" % str(background))
# Convert to packed uint
bg_r, bg_g, bg_b, bg_a = background
background = (bg_a << 24) | (bg_r << 16) | (bg_g << 8) | (bg_b << 0)
# Setup the WebP animation encoder
enc = _webp.WebPAnimEncoder(
im.size[0], im.size[1],
background,
loop,
minimize_size,
kmin, kmax,
allow_mixed,
verbose
)
# Add each frame
frame_idx = 0
timestamp = 0
cur_idx = im.tell()
try:
for ims in [im]+append_images:
# Get # of frames in this image
if not hasattr(ims, "n_frames"):
nfr = 1
else:
nfr = ims.n_frames
for idx in range(nfr):
ims.seek(idx)
ims.load()
# Make sure image mode is supported
frame = ims
rawmode = ims.mode
if ims.mode not in _VALID_WEBP_MODES:
alpha = 'A' in ims.mode or 'a' in ims.mode \
or (ims.mode == 'P' and
'A' in ims.im.getpalettemode())
rawmode = 'RGBA' if alpha else 'RGB'
frame = ims.convert(rawmode)
if rawmode == 'RGB':
# For faster conversion, use RGBX
rawmode = 'RGBX'
# Append the frame to the animation encoder
enc.add(
frame.tobytes('raw', rawmode),
timestamp,
frame.size[0], frame.size[1],
rawmode,
lossless,
quality,
method
)
# Update timestamp and frame index
if isinstance(duration, (list, tuple)):
timestamp += duration[frame_idx]
else:
timestamp += duration
frame_idx += 1
finally:
im.seek(cur_idx)
# Force encoder to flush frames
enc.add(
None,
timestamp,
0, 0, "", lossless, quality, 0
)
# Get the final output from the encoder
data = enc.assemble(icc_profile, exif, xmp)
if data is None:
raise IOError("cannot write file as WebP (encoder returned None)")
fp.write(data)
def _save(im, fp, filename):
lossless = im.encoderinfo.get("lossless", False)
quality = im.encoderinfo.get("quality", 80)
icc_profile = im.encoderinfo.get("icc_profile", "")
exif = im.encoderinfo.get("exif", "")
xmp = im.encoderinfo.get("xmp", "")
if im.mode not in _VALID_WEBP_LEGACY_MODES:
alpha = 'A' in im.mode or 'a' in im.mode \
or (im.mode == 'P' and 'A' in im.im.getpalettemode())
im = im.convert('RGBA' if alpha else 'RGB')
data = _webp.WebPEncode(
im.tobytes(),
im.size[0],
im.size[1],
lossless,
float(quality),
im.mode,
icc_profile,
exif,
xmp
)
if data is None:
raise IOError("cannot write file as WebP (encoder returned None)")
fp.write(data)
Image.register_open(WebPImageFile.format, WebPImageFile, _accept)
if SUPPORTED:
Image.register_save(WebPImageFile.format, _save)
if _webp.HAVE_WEBPANIM:
Image.register_save_all(WebPImageFile.format, _save_all)
Image.register_extension(WebPImageFile.format, ".webp")
Image.register_mime(WebPImageFile.format, "image/webp")