pmtiles 0.23.0

Implementation of the PMTiles v3 spec with multiple sync and async backends.
Documentation 
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

use std::io::Write;

use flate2::write::GzEncoder;

use crate::{Compression, PmtError, PmtResult};

/// Trait for compression implementations.
/// Implement this to provide custom compression behavior.
pub trait Compressor {
    /// Returns the compression type for the `PMTiles` header.
    fn compression(&self) -> Compression;

    /// Invoke `f` to write uncompressed data into an encoder
    /// wrapping `writer`, then finalize the encoder.
    ///
    /// # Errors
    ///
    /// Returns an error if writing to `output` fails or the compression fails.
    fn compress(
        &self,
        f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        writer: &mut dyn Write,
    ) -> PmtResult<()>;
}

impl<T: Compressor + ?Sized> Compressor for Box<T> {
    fn compression(&self) -> Compression {
        (**self).compression()
    }

    fn compress(
        &self,
        f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        writer: &mut dyn Write,
    ) -> PmtResult<()> {
        (**self).compress(f, writer)
    }
}

/// Passthrough (no compression).
pub(crate) struct NoCompression;

impl Compressor for NoCompression {
    fn compression(&self) -> Compression {
        Compression::None
    }

    fn compress(
        &self,
        f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        writer: &mut dyn Write,
    ) -> PmtResult<()> {
        f(writer)?;
        Ok(())
    }
}

/// Gzip compression. Wraps [`flate2::Compression`] for level configuration.
#[derive(Default)]
pub(crate) struct GzipCompressor(pub(crate) flate2::Compression);

impl Compressor for GzipCompressor {
    fn compression(&self) -> Compression {
        Compression::Gzip
    }

    fn compress(
        &self,
        f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        writer: &mut dyn Write,
    ) -> PmtResult<()> {
        let mut encoder = GzEncoder::new(writer, self.0);
        f(&mut encoder)?;
        encoder.finish()?;
        Ok(())
    }
}

/// Brotli compression. Wraps [`brotli::enc::BrotliEncoderParams`].
#[cfg(feature = "brotli")]
#[derive(Default)]
pub(crate) struct BrotliCompressor(pub(crate) brotli::enc::BrotliEncoderParams);

#[cfg(feature = "brotli")]
impl Compressor for BrotliCompressor {
    fn compression(&self) -> Compression {
        Compression::Brotli
    }

    fn compress(
        &self,
        f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        writer: &mut dyn Write,
    ) -> PmtResult<()> {
        let mut encoder = brotli::CompressorWriter::with_params(writer, 4096, &self.0);
        f(&mut encoder)?;
        Ok(())
    }
}

/// Zstd compression with configurable level.
#[cfg(feature = "zstd")]
pub(crate) struct ZstdCompressor(pub(crate) i32);

#[cfg(feature = "zstd")]
impl Compressor for ZstdCompressor {
    fn compression(&self) -> Compression {
        Compression::Zstd
    }

    fn compress(
        &self,
        f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        writer: &mut dyn Write,
    ) -> PmtResult<()> {
        let mut encoder = zstd::stream::Encoder::new(writer, self.0)?;
        f(&mut encoder)?;
        encoder.finish()?;
        Ok(())
    }
}

#[cfg(feature = "zstd")]
impl Default for ZstdCompressor {
    fn default() -> Self {
        Self(zstd::DEFAULT_COMPRESSION_LEVEL)
    }
}

impl From<Compression> for Box<dyn Compressor> {
    fn from(compression: Compression) -> Self {
        match compression {
            Compression::None => Box::new(NoCompression),
            Compression::Gzip => Box::new(GzipCompressor::default()),
            #[cfg(feature = "brotli")]
            Compression::Brotli => Box::new(BrotliCompressor::default()),
            #[cfg(feature = "zstd")]
            Compression::Zstd => Box::new(ZstdCompressor::default()),
            v => Box::new(UnsupportedCompressor(v)),
        }
    }
}

/// Stub compressor for codecs whose feature is disabled.
/// Returns an error when compression is attempted.
struct UnsupportedCompressor(Compression);

impl Compressor for UnsupportedCompressor {
    fn compression(&self) -> Compression {
        self.0
    }

    fn compress(
        &self,
        _f: &mut dyn FnMut(&mut dyn Write) -> std::io::Result<()>,
        _writer: &mut dyn Write,
    ) -> PmtResult<()> {
        Err(PmtError::UnsupportedCompression(self.0))
    }
}