1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
use byteorder::{LittleEndian, ReadBytesExt};
use std::convert::TryFrom;
use std::io::{self, Cursor, Error, Read};
use std::marker::PhantomData;
use std::{error, fmt, mem};

use crate::error::{DecodingError, ImageError, ImageResult, ParameterError, ParameterErrorKind};
use crate::image::{ImageDecoder, ImageFormat};
use crate::{color, AnimationDecoder, Frames, Rgba};

use super::lossless::{LosslessDecoder, LosslessFrame};
use super::vp8::{Frame as VP8Frame, Vp8Decoder};

use super::extended::{read_extended_header, ExtendedImage};

/// All errors that can occur when attempting to parse a WEBP container
#[derive(Debug, Clone, Copy)]
pub(crate) enum DecoderError {
    /// RIFF's "RIFF" signature not found or invalid
    RiffSignatureInvalid([u8; 4]),
    /// WebP's "WEBP" signature not found or invalid
    WebpSignatureInvalid([u8; 4]),
    /// Chunk Header was incorrect or invalid in its usage
    ChunkHeaderInvalid([u8; 4]),
}

impl fmt::Display for DecoderError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        struct SignatureWriter([u8; 4]);
        impl fmt::Display for SignatureWriter {
            fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                write!(
                    f,
                    "[{:#04X?}, {:#04X?}, {:#04X?}, {:#04X?}]",
                    self.0[0], self.0[1], self.0[2], self.0[3]
                )
            }
        }

        match self {
            DecoderError::RiffSignatureInvalid(riff) => f.write_fmt(format_args!(
                "Invalid RIFF signature: {}",
                SignatureWriter(*riff)
            )),
            DecoderError::WebpSignatureInvalid(webp) => f.write_fmt(format_args!(
                "Invalid WebP signature: {}",
                SignatureWriter(*webp)
            )),
            DecoderError::ChunkHeaderInvalid(header) => f.write_fmt(format_args!(
                "Invalid Chunk header: {}",
                SignatureWriter(*header)
            )),
        }
    }
}

impl From<DecoderError> for ImageError {
    fn from(e: DecoderError) -> ImageError {
        ImageError::Decoding(DecodingError::new(ImageFormat::WebP.into(), e))
    }
}

impl error::Error for DecoderError {}

/// All possible RIFF chunks in a WebP image file
#[allow(clippy::upper_case_acronyms)]
#[derive(Debug, Clone, Copy, PartialEq)]
pub(crate) enum WebPRiffChunk {
    RIFF,
    WEBP,
    VP8,
    VP8L,
    VP8X,
    ANIM,
    ANMF,
    ALPH,
    ICCP,
    EXIF,
    XMP,
}

impl WebPRiffChunk {
    pub(crate) fn from_fourcc(chunk_fourcc: [u8; 4]) -> ImageResult<Self> {
        match &chunk_fourcc {
            b"RIFF" => Ok(Self::RIFF),
            b"WEBP" => Ok(Self::WEBP),
            b"VP8 " => Ok(Self::VP8),
            b"VP8L" => Ok(Self::VP8L),
            b"VP8X" => Ok(Self::VP8X),
            b"ANIM" => Ok(Self::ANIM),
            b"ANMF" => Ok(Self::ANMF),
            b"ALPH" => Ok(Self::ALPH),
            b"ICCP" => Ok(Self::ICCP),
            b"EXIF" => Ok(Self::EXIF),
            b"XMP " => Ok(Self::XMP),
            _ => Err(DecoderError::ChunkHeaderInvalid(chunk_fourcc).into()),
        }
    }

    pub(crate) fn to_fourcc(&self) -> [u8; 4] {
        match self {
            Self::RIFF => *b"RIFF",
            Self::WEBP => *b"WEBP",
            Self::VP8 => *b"VP8 ",
            Self::VP8L => *b"VP8L",
            Self::VP8X => *b"VP8X",
            Self::ANIM => *b"ANIM",
            Self::ANMF => *b"ANMF",
            Self::ALPH => *b"ALPH",
            Self::ICCP => *b"ICCP",
            Self::EXIF => *b"EXIF",
            Self::XMP => *b"XMP ",
        }
    }
}

enum WebPImage {
    Lossy(VP8Frame),
    Lossless(LosslessFrame),
    Extended(ExtendedImage),
}

/// WebP Image format decoder. Currently only supports lossy RGB images or lossless RGBA images.
pub struct WebPDecoder<R> {
    r: R,
    image: WebPImage,
}

impl<R: Read> WebPDecoder<R> {
    /// Create a new WebPDecoder from the Reader ```r```.
    /// This function takes ownership of the Reader.
    pub fn new(r: R) -> ImageResult<WebPDecoder<R>> {
        let image = WebPImage::Lossy(Default::default());

        let mut decoder = WebPDecoder { r, image };
        decoder.read_data()?;
        Ok(decoder)
    }

    //reads the 12 bytes of the WebP file header
    fn read_riff_header(&mut self) -> ImageResult<u32> {
        let mut riff = [0; 4];
        self.r.read_exact(&mut riff)?;
        if &riff != b"RIFF" {
            return Err(DecoderError::RiffSignatureInvalid(riff).into());
        }

        let size = self.r.read_u32::<LittleEndian>()?;

        let mut webp = [0; 4];
        self.r.read_exact(&mut webp)?;
        if &webp != b"WEBP" {
            return Err(DecoderError::WebpSignatureInvalid(webp).into());
        }

        Ok(size)
    }

    //reads the chunk header, decodes the frame and returns the inner decoder
    fn read_frame(&mut self) -> ImageResult<WebPImage> {
        let chunk = read_chunk(&mut self.r)?;

        match chunk {
            Some((cursor, WebPRiffChunk::VP8)) => {
                let mut vp8_decoder = Vp8Decoder::new(cursor);
                let frame = vp8_decoder.decode_frame()?;

                Ok(WebPImage::Lossy(frame.clone()))
            }
            Some((cursor, WebPRiffChunk::VP8L)) => {
                let mut lossless_decoder = LosslessDecoder::new(cursor);
                let frame = lossless_decoder.decode_frame()?;

                Ok(WebPImage::Lossless(frame.clone()))
            }
            Some((mut cursor, WebPRiffChunk::VP8X)) => {
                let info = read_extended_header(&mut cursor)?;

                let image = ExtendedImage::read_extended_chunks(&mut self.r, info)?;

                Ok(WebPImage::Extended(image))
            }
            None => Err(ImageError::IoError(Error::from(
                io::ErrorKind::UnexpectedEof,
            ))),
            Some((_, chunk)) => Err(DecoderError::ChunkHeaderInvalid(chunk.to_fourcc()).into()),
        }
    }

    fn read_data(&mut self) -> ImageResult<()> {
        let _size = self.read_riff_header()?;

        let image = self.read_frame()?;

        self.image = image;

        Ok(())
    }

    /// Returns true if the image as described by the bitstream is animated.
    pub fn has_animation(&self) -> bool {
        match &self.image {
            WebPImage::Lossy(_) => false,
            WebPImage::Lossless(_) => false,
            WebPImage::Extended(extended) => extended.has_animation(),
        }
    }

    /// Sets the background color if the image is an extended and animated webp.
    pub fn set_background_color(&mut self, color: Rgba<u8>) -> ImageResult<()> {
        match &mut self.image {
            WebPImage::Extended(image) => image.set_background_color(color),
            _ => Err(ImageError::Parameter(ParameterError::from_kind(
                ParameterErrorKind::Generic(
                    "Background color can only be set on animated webp".to_owned(),
                ),
            ))),
        }
    }
}

pub(crate) fn read_len_cursor<R>(r: &mut R) -> ImageResult<Cursor<Vec<u8>>>
where
    R: Read,
{
    let unpadded_len = u64::from(r.read_u32::<LittleEndian>()?);

    // RIFF chunks containing an uneven number of bytes append
    // an extra 0x00 at the end of the chunk
    //
    // The addition cannot overflow since we have a u64 that was created from a u32
    let len = unpadded_len + (unpadded_len % 2);

    let mut framedata = Vec::new();
    r.by_ref().take(len).read_to_end(&mut framedata)?;

    //remove padding byte
    if unpadded_len % 2 == 1 {
        framedata.pop();
    }

    Ok(io::Cursor::new(framedata))
}

/// Reads a chunk header FourCC
/// Returns None if and only if we hit end of file reading the four character code of the chunk
/// The inner error is `Err` if and only if the chunk header FourCC is present but unknown
pub(crate) fn read_fourcc<R: Read>(r: &mut R) -> ImageResult<Option<ImageResult<WebPRiffChunk>>> {
    let mut chunk_fourcc = [0; 4];
    let result = r.read_exact(&mut chunk_fourcc);

    match result {
        Ok(()) => {}
        Err(err) => {
            if err.kind() == io::ErrorKind::UnexpectedEof {
                return Ok(None);
            } else {
                return Err(err.into());
            }
        }
    }

    let chunk = WebPRiffChunk::from_fourcc(chunk_fourcc);
    Ok(Some(chunk))
}

/// Reads a chunk
/// Returns an error if the chunk header is not a valid webp header or some other reading error
/// Returns None if and only if we hit end of file reading the four character code of the chunk
pub(crate) fn read_chunk<R>(r: &mut R) -> ImageResult<Option<(Cursor<Vec<u8>>, WebPRiffChunk)>>
where
    R: Read,
{
    if let Some(chunk) = read_fourcc(r)? {
        let chunk = chunk?;
        let cursor = read_len_cursor(r)?;
        Ok(Some((cursor, chunk)))
    } else {
        Ok(None)
    }
}

/// Wrapper struct around a `Cursor<Vec<u8>>`
pub struct WebpReader<R>(Cursor<Vec<u8>>, PhantomData<R>);
impl<R> Read for WebpReader<R> {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        self.0.read(buf)
    }
    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
        if self.0.position() == 0 && buf.is_empty() {
            mem::swap(buf, self.0.get_mut());
            Ok(buf.len())
        } else {
            self.0.read_to_end(buf)
        }
    }
}

impl<'a, R: 'a + Read> ImageDecoder<'a> for WebPDecoder<R> {
    type Reader = WebpReader<R>;

    fn dimensions(&self) -> (u32, u32) {
        match &self.image {
            WebPImage::Lossy(vp8_frame) => {
                (u32::from(vp8_frame.width), u32::from(vp8_frame.height))
            }
            WebPImage::Lossless(lossless_frame) => (
                u32::from(lossless_frame.width),
                u32::from(lossless_frame.height),
            ),
            WebPImage::Extended(extended) => extended.dimensions(),
        }
    }

    fn color_type(&self) -> color::ColorType {
        match &self.image {
            WebPImage::Lossy(_) => color::ColorType::Rgb8,
            WebPImage::Lossless(_) => color::ColorType::Rgba8,
            WebPImage::Extended(extended) => extended.color_type(),
        }
    }

    fn into_reader(self) -> ImageResult<Self::Reader> {
        match &self.image {
            WebPImage::Lossy(vp8_frame) => {
                let mut data = vec![0; vp8_frame.get_buf_size()];
                vp8_frame.fill_rgb(data.as_mut_slice());
                Ok(WebpReader(Cursor::new(data), PhantomData))
            }
            WebPImage::Lossless(lossless_frame) => {
                let mut data = vec![0; lossless_frame.get_buf_size()];
                lossless_frame.fill_rgba(data.as_mut_slice());
                Ok(WebpReader(Cursor::new(data), PhantomData))
            }
            WebPImage::Extended(extended) => {
                let mut data = vec![0; extended.get_buf_size()];
                extended.fill_buf(data.as_mut_slice());
                Ok(WebpReader(Cursor::new(data), PhantomData))
            }
        }
    }

    fn read_image(self, buf: &mut [u8]) -> ImageResult<()> {
        assert_eq!(u64::try_from(buf.len()), Ok(self.total_bytes()));

        match &self.image {
            WebPImage::Lossy(vp8_frame) => {
                vp8_frame.fill_rgb(buf);
            }
            WebPImage::Lossless(lossless_frame) => {
                lossless_frame.fill_rgba(buf);
            }
            WebPImage::Extended(extended) => {
                extended.fill_buf(buf);
            }
        }
        Ok(())
    }

    fn icc_profile(&mut self) -> Option<Vec<u8>> {
        if let WebPImage::Extended(extended) = &self.image {
            extended.icc_profile()
        } else {
            None
        }
    }
}

impl<'a, R: 'a + Read> AnimationDecoder<'a> for WebPDecoder<R> {
    fn into_frames(self) -> Frames<'a> {
        match self.image {
            WebPImage::Lossy(_) | WebPImage::Lossless(_) => {
                Frames::new(Box::new(std::iter::empty()))
            }
            WebPImage::Extended(extended_image) => extended_image.into_frames(),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn add_with_overflow_size() {
        let bytes = vec![
            0x52, 0x49, 0x46, 0x46, 0xaf, 0x37, 0x80, 0x47, 0x57, 0x45, 0x42, 0x50, 0x6c, 0x64,
            0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xfb, 0x7e, 0x73, 0x00, 0x06, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65,
            0x40, 0xfb, 0xff, 0xff, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65, 0x65,
            0x00, 0x00, 0x00, 0x00, 0x62, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x49,
            0x49, 0x54, 0x55, 0x50, 0x4c, 0x54, 0x59, 0x50, 0x45, 0x33, 0x37, 0x44, 0x4d, 0x46,
        ];

        let data = std::io::Cursor::new(bytes);

        let _ = WebPDecoder::new(data);
    }
}