imagesize/formats/
webp.rs

1use crate::util::*;
2use crate::{ImageResult, ImageSize};
3
4use std::io::{BufRead, Seek, SeekFrom};
5
6pub fn size<R: BufRead + Seek>(reader: &mut R) -> ImageResult<ImageSize> {
7    let mut buffer = [0; 4];
8    reader.read_exact(&mut buffer)?;
9
10    if buffer[3] == b' ' {
11        webp_vp8_size(reader)
12    } else if buffer[3] == b'L' {
13        webp_vp8l_size(reader)
14    } else if buffer[3] == b'X' {
15        webp_vp8x_size(reader)
16    } else {
17        Err(std::io::Error::new(std::io::ErrorKind::InvalidData, "Invalid VP8 Tag").into())
18    }
19}
20
21pub fn matches(header: &[u8]) -> bool {
22    header.len() >= 12 && &header[0..4] == b"RIFF" && &header[8..12] == b"WEBP"
23}
24
25fn webp_vp8x_size<R: BufRead + Seek>(reader: &mut R) -> ImageResult<ImageSize> {
26    reader.seek(SeekFrom::Start(0x18))?;
27
28    Ok(ImageSize {
29        width: read_u24(reader, &Endian::Little)? as usize + 1,
30        height: read_u24(reader, &Endian::Little)? as usize + 1,
31    })
32}
33
34fn webp_vp8l_size<R: BufRead + Seek>(reader: &mut R) -> ImageResult<ImageSize> {
35    reader.seek(SeekFrom::Start(0x15))?;
36
37    let dims = read_u32(reader, &Endian::Little)?;
38
39    Ok(ImageSize {
40        width: (dims & 0x3FFF) as usize + 1,
41        height: ((dims >> 14) & 0x3FFF) as usize + 1,
42    })
43}
44
45fn webp_vp8_size<R: BufRead + Seek>(reader: &mut R) -> ImageResult<ImageSize> {
46    reader.seek(SeekFrom::Start(0x1A))?;
47
48    Ok(ImageSize {
49        width: read_u16(reader, &Endian::Little)? as usize,
50        height: read_u16(reader, &Endian::Little)? as usize,
51    })
52}