      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

    //! All IO functionality needed for TIFF decoding

    use std::io::{self, Read, Seek};
    use byteorder::{ReadBytesExt, BigEndian, LittleEndian};
    use lzw;

    /// Byte order of the TIFF file.
    #[derive(Clone, Copy, Debug)]
    pub enum ByteOrder {
        /// little endian byte order
        LittleEndian,
        /// big endian byte order
        BigEndian
    }

    /// Reader that is aware of the byte order.
    pub trait EndianReader: Read {
        /// Byte order that should be adhered to
        fn byte_order(&self) -> ByteOrder;

        /// Reads an u16
        #[inline(always)]
        fn read_u16(&mut self) -> Result<u16, io::Error> {
            match self.byte_order() {
                ByteOrder::LittleEndian => <Self as ReadBytesExt>::read_u16::<LittleEndian>(self),
                ByteOrder::BigEndian => <Self as ReadBytesExt>::read_u16::<BigEndian>(self)
            }
        }

        #[inline(always)]
        fn read_u16_into(&mut self, buffer: &mut [u16]) -> Result<(), io::Error> {
            match self.byte_order() {
                ByteOrder::LittleEndian => <Self as ReadBytesExt>::read_u16_into::<LittleEndian>(self, buffer),
                ByteOrder::BigEndian => <Self as ReadBytesExt>::read_u16_into::<BigEndian>(self, buffer)
            }
        }

        /// Reads an u32
        #[inline(always)]
        fn read_u32(&mut self) -> Result<u32, io::Error> {
            match self.byte_order() {
                ByteOrder::LittleEndian => <Self as ReadBytesExt>::read_u32::<LittleEndian>(self),
                ByteOrder::BigEndian => <Self as ReadBytesExt>::read_u32::<BigEndian>(self)
            }
        }
    }

    /// Reader that decompresses LZW streams
    pub struct LZWReader {
        buffer: io::Cursor<Vec<u8>>,
        byte_order: ByteOrder
    }

    impl LZWReader {
        /// Wraps a reader
        pub fn new<R>(reader: &mut SmartReader<R>, compressed_length: usize, max_uncompressed_length: usize) -> io::Result<(usize, LZWReader)> where R: Read + Seek {
            let order = reader.byte_order;
            let mut compressed = vec![0; compressed_length as usize];
            try!(reader.read_exact(&mut compressed[..]));
            let mut uncompressed = Vec::with_capacity(max_uncompressed_length);
            let mut decoder = lzw::DecoderEarlyChange::new(lzw::MsbReader::new(), 8);
            let mut bytes_read = 0;
            while bytes_read < compressed_length && uncompressed.len() < max_uncompressed_length {
                let (len, bytes) = try!(decoder.decode_bytes(&compressed[bytes_read..]));
                bytes_read += len;
                uncompressed.extend_from_slice(bytes);
            }

            let bytes = uncompressed.len();
            Ok((bytes, LZWReader {
                buffer: io::Cursor::new(uncompressed),
                byte_order: order
            }))
        }
    }

    impl Read for LZWReader {
        #[inline]
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.buffer.read(buf)
        }
    }

    impl EndianReader for LZWReader {
        #[inline(always)]
        fn byte_order(&self) -> ByteOrder {
            self.byte_order
        }
    }

    /// Reader that unpacks Apple's `PackBits` format
    pub struct PackBitsReader {
        buffer: io::Cursor<Vec<u8>>,
        byte_order: ByteOrder
    }

    impl PackBitsReader {
        /// Wraps a reader
        pub fn new<R: Read + Seek>(mut reader: R, byte_order: ByteOrder, length: usize) -> io::Result<(usize, PackBitsReader)> {
            let mut buffer = Vec::new();
            let mut read: usize = 0;
            while read < length {
                read += try!(read_packbits_run(&mut reader, &mut buffer));
            }
            Ok((buffer.len(), PackBitsReader {
                buffer: io::Cursor::new(buffer),
                byte_order
            }))
        }
    }

    fn read_packbits_run<R: Read + Seek>(reader: &mut R, buffer: &mut Vec<u8>) -> io::Result<usize> {
        let mut header: [u8; 1] = [0];

        let bytes = try!(reader.read(&mut header));

        match bytes {
            0 => Ok(0),
            _ => match header[0] as i8 {
                -128 => Ok(1),
                h if h >= -127 && h <= -1 => {
                    let new_len = buffer.len() + (1 - h as isize) as usize;
                    try!(reader.read_exact(&mut header));
                    buffer.resize(new_len, header[0]);
                    Ok(2)
                },
                h => {
                    let num_vals = h as usize + 1;
                    let start = buffer.len();
                    buffer.resize(start + num_vals, 0);
                    try!(reader.read_exact(&mut buffer[start..]));
                    Ok(num_vals + 1)
                }
            }
        }
    }

    impl Read for PackBitsReader {
        #[inline]
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.buffer.read(buf)
        }
    }

    impl EndianReader for PackBitsReader {
        #[inline(always)]
        fn byte_order(&self) -> ByteOrder {
            self.byte_order
        }
    }

    /// Reader that is aware of the byte order.
    #[derive(Debug)]
    pub struct SmartReader<R> where R: Read + Seek {
        reader: R,
        pub byte_order: ByteOrder
    }

    impl<R> SmartReader<R> where R: Read + Seek {
        /// Wraps a reader
        pub fn wrap(reader: R, byte_order: ByteOrder) -> SmartReader<R> {
            SmartReader { reader, byte_order }
        }
    }

    impl<R> EndianReader for SmartReader<R> where R: Read + Seek {
        #[inline(always)]
        fn byte_order(&self) -> ByteOrder {
            self.byte_order
        }
    }

    impl<R: Read + Seek> Read for SmartReader<R> {
        #[inline]
        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
            self.reader.read(buf)
        }
    }

    impl<R: Read + Seek> Seek for SmartReader<R> {
        #[inline]
        fn seek(&mut self, pos: io::SeekFrom) -> io::Result<u64> {
            self.reader.seek(pos)
        }
    }

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

        #[test]
        fn test_packbits() {
            let encoded = vec![0xFE, 0xAA, 0x02, 0x80, 0x00, 0x2A, 0xFD, 0xAA,
                               0x03, 0x80, 0x00, 0x2A, 0x22, 0xF7, 0xAA];
            let encoded_len = encoded.len();

            let buff = io::Cursor::new(encoded);
            let (_, mut decoder) = PackBitsReader::new(buff, ByteOrder::LittleEndian, encoded_len).unwrap();

            let mut decoded = Vec::new();
            decoder.read_to_end(&mut decoded).unwrap();

            let expected = vec![0xAA, 0xAA, 0xAA, 0x80, 0x00, 0x2A, 0xAA, 0xAA,
                                0xAA, 0xAA, 0x80, 0x00, 0x2A, 0x22, 0xAA, 0xAA,
                                0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA];
            assert_eq!(decoded, expected);
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)