Webp support

src/docx/image/__init__.py

@@ -9,6 +9,7 @@
 from docx.image.jpeg import Exif, Jfif
 from docx.image.png import Png
 from docx.image.tiff import Tiff
+from docx.image.webp import Webp
 
 SIGNATURES = (
     # class, offset, signature_bytes
@@ -20,4 +21,5 @@
     (Tiff, 0, b"MM\x00*"),  # big-endian (Motorola) TIFF
     (Tiff, 0, b"II*\x00"),  # little-endian (Intel) TIFF
     (Bmp, 0, b"BM"),
+    (Webp, 0, b"RIFF"),
 )

src/docx/image/constants.py

@@ -105,6 +105,7 @@ class MIME_TYPE:
     JPEG = "image/jpeg"
     PNG = "image/png"
     TIFF = "image/tiff"
+    WEBP = "image/webp"
 
 
 class PNG_CHUNK_TYPE:

src/docx/image/webp.py

@@ -0,0 +1,257 @@
+"""Objects related to parsing headers of WEBP image streams.
+
+Docs: https://developers.google.com/speed/webp/docs/riff_container
+
+VP8:
+
+ 0                   1                   2                   3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      'R'      |      'I'      |      'F'      |      'F'      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                           File Size                           |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      'W'      |      'E'      |      'B'      |      'P'      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                      ChunkHeader('VP8 ')                      |
+|                                                               |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+:                           VP8 data                            :
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+1. Data begins with string RIFF
+2. Little-endian 32-bit file size
+3. String WEBP
+4. String VP8 (with space)
+5. Little-endian 32-bit chunk size
+6. 3-byte frame tag for interframes, or 10-byte frame tag for keyframes
+7. Compressed data partitions containing:
+   - Frame header
+   - Macroblock prediction data
+   - DCT/WHT coefficient data
+The frame dimensions are encoded in the frame header within the first compressed data partition, 
+not in a fixed position like VP8L.
+
+VP8L:
+
+ 0                   1                   2                   3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      'R'      |      'I'      |      'F'      |      'F'      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                           File Size                           |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      'W'      |      'E'      |      'B'      |      'P'      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                      ChunkHeader('VP8L')                      |
+|                                                               |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+:                           VP8L data                           :
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+1. Data begins with the string RIFF 
+2. A little endian 32 bit value 
+3. String WEBP 
+4. String VP8L 
+5. A little endian 32 bit value 
+6. 1 byte signature 0x2f And then the first 28 bits contains the width and the height
+
+VP8X:
+
+ 0                   1                   2                   3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      'R'      |      'I'      |      'F'      |      'F'      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                           File Size                           |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|      'W'      |      'E'      |      'B'      |      'P'      |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                      ChunkHeader('VP8X')                      |
+|                                                               |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|Rsv|I|L|E|X|A|R|                   Reserved                    |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|          Canvas Width Minus One               |             ...
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+...  Canvas Height Minus One    |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+1. Data begins with string RIFF
+2. Little-endian 32-bit file size
+3. String WEBP
+4. String VP8X
+5. Little-endian 32-bit chunk size
+6. Reeserved (Rsv): 2 bits (MUST be 0. Readers MUST ignore this field.)
+7. ICC profile (I): 1 bit (Set if the file contains an 'ICCP' Chunk.)
+8. Alpha (L): 1 bit (Set if any of the frames of the image contain transparency information ("alpha").)
+9. Exif metadata (E): 1 bit (Set if the file contains Exif metadata.)
+10. XMP metadata (X): 1 bit (Set if the file contains XMP metadata.)
+11. Animation (A): 1 bit (Set if this is an animated image. Data in 'ANIM' and 'ANMF' Chunks should be used to control the animation.)
+12. Reserved (R): 1 bit (MUST be 0. Readers MUST ignore this field.)
+13. Reserved: 24 bits (MUST be 0. Readers MUST ignore this field.)
+14. Canvas Width Minus One: 24 bits (1-based width of the canvas in pixels. The actual canvas width is 1 + Canvas Width Minus One.)
+15. Canvas Height Minus One: 24 bits (1-based height of the canvas in pixels. The actual canvas height is 1 + Canvas Height Minus One.)
+16. The product of Canvas Width and Canvas Height MUST be at most 2^32 - 1.
+"""
+
+from struct import unpack
+
+from docx.image.constants import MIME_TYPE
+from docx.image.helpers import BIG_ENDIAN, StreamReader
+from docx.image.image import BaseImageHeader
+
+
+class Webp(BaseImageHeader):
+    """Image header parser for WEBP image format."""
+
+    @classmethod
+    def from_stream(cls, stream):
+        """Return |Webp| instance having header properties parsed from WEBP image in
+        `stream`."""
+        stream.seek(0)
+        if stream.read(4) != b'RIFF':
+            raise ValueError("Not a valid WebP file")
+
+        _ = stream.read(4)  # File size, we can skip this
+
+        if stream.read(4) != b'WEBP':
+            raise ValueError("Not a valid WebP file")
+
+        chunk_header = stream.read(4)
+
+        if chunk_header == b'VP8L':
+            width, height = cls._parse_lossless(stream)
+        elif chunk_header == b'VP8X':
+            width, height = cls._parse_extended(stream)
+        elif chunk_header == b'VP8 ':
+            width, height = cls._parse_simple(stream)
+        else:
+            raise ValueError("Unsupported WebP format")
+
+        return cls(width, height, 72, 72)
+
+    @staticmethod
+    def _parse_lossless(stream):
+        _ = unpack('<I', stream.read(4))[0]  # Chunk size, we can skip this
+
+        signature = stream.read(1)[0]
+        if signature != 0x2f:
+            raise ValueError("Invalid lossless WebP signature")
+
+        data = stream.read(4)
+        bits = int.from_bytes(data, 'little')
+
+        w = (bits & 0x3FFF) + 1
+        h = ((bits >> 14) & 0x3FFF) + 1
+
+        return w, h
+
+    @staticmethod
+    def _parse_extended(stream):
+        _ = unpack('<I', stream.read(4))[0]  # Chunk size, we can skip this
+
+        _ = stream.read(4)  # Skip flags
+
+        width_minus_one = int.from_bytes(stream.read(3), 'little')
+        height_minus_one = int.from_bytes(stream.read(3), 'little')
+
+        w = width_minus_one + 1
+        h = height_minus_one + 1
+
+        return w, h
+
+    @staticmethod
+    def _parse_simple(stream):
+        stream.seek(9, 1)  # Skip 9 bytes
+
+        bits = stream.read(2)
+        w = ((bits[1] & 0x3F) << 8) | bits[0]
+        h = (bits[1] & 0xC0) | stream.read(1)[0]
+
+        return w, h
+
+    @property
+    def content_type(self):
+        """MIME content type for this image."""
+        return MIME_TYPE.WEBP
+
+    @property
+    def default_ext(self):
+        """Default filename extension, always 'webp' for WEBP images."""
+        return 'webp'
+
+class _WebpParser:
+    """Parser for WebP image binary data."""
+
+    def __init__(self, stream):
+        self._stream = stream
+        self._stream_rdr = StreamReader(stream, BIG_ENDIAN)
+        self._width = None
+        self._height = None
+
+    @property
+    def px_width(self):
+        self._parse_dimensions()
+        return self._width
+
+    @property
+    def px_height(self):
+        self._parse_dimensions()
+        return self._height
+
+    @property
+    def horz_dpi(self):
+        return 72
+
+    @property
+    def vert_dpi(self):
+        return 72
+
+    def _parse_dimensions(self):
+        if self._width is not None:
+            return
+
+        self._stream_rdr.seek(12)  # Skip RIFF header
+        vp8_header = self._stream_rdr.read(4)
+
+        if vp8_header == b'VP8 ':
+            self._parse_simple_webp()
+        elif vp8_header == b'VP8L':
+            self._parse_lossless_webp()
+        elif vp8_header == b'VP8X':
+            self._parse_extended_webp()
+        else:
+            raise ValueError('Unsupported WebP format')
+
+    def _parse_simple_webp(self):
+        self._stream_rdr.skip(3)  # Skip frame tag for interframes
+        frame_tag = self._stream_rdr.read(1)
+        if frame_tag[0] & 0x1:  # Check if it's a keyframe
+            self._stream_rdr.skip(6)  # Skip rest of keyframe tag
+        else:
+            self._stream_rdr.seek(-3, 1)  # Go back to start of frame tag
+
+        # Read first two bytes of frame header
+        bits = self._stream_rdr.read(2)
+        self._width = ((bits[1] & 0x3F) << 8) | bits[0]
+        self._height = (bits[1] & 0xC0) | self._stream_rdr.read(1)[0]
+
+    def _parse_lossless_webp(self):
+        self._stream_rdr.skip(1)
+        bits = self._stream_rdr.read(4)
+        self._width = 1 + ((bits[1] & 63) << 8 | bits[0])
+        self._height = 1 + ((bits[3] & 15) << 10 | bits[2] << 2 | (bits[1] & 192) >> 6)
+
+    def _parse_extended_webp(self):
+        self._stream_rdr.skip(8)  # Skip chunk size and flags
+        width_minus_one = int.from_bytes(self._stream_rdr.read(3), 'little')
+        height_minus_one = int.from_bytes(self._stream_rdr.read(3), 'little')
+        self._width = width_minus_one + 1
+        self._height = height_minus_one + 1
+
+    @classmethod
+    def parse(cls, stream):
+        parser = cls(stream)
+        return parser