lodepng 2.1.2

Reading and writing PNG files without system dependencies. Pure Rust port of LodePNG.
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

use std;
use std::ffi::CStr;
use std::marker::PhantomData;
use super::ChunkRef;
use rustimpl;

pub struct TextKeysCStrIter<'a> {
    pub(crate) k: *mut *mut i8,
    pub(crate) v: *mut *mut i8,
    pub(crate) n: usize,
    pub(crate) _p: PhantomData<&'a CStr>,
}

impl<'a> Iterator for TextKeysCStrIter<'a> {
    type Item = (&'a CStr, &'a CStr);
    fn next(&mut self) -> Option<Self::Item> {
        if self.n > 0 {
            unsafe {
                debug_assert!(!(*self.k).is_null()); let k = CStr::from_ptr(*self.k);
                debug_assert!(!(*self.v).is_null()); let v = CStr::from_ptr(*self.v);
                self.n -= 1;
                self.k = self.k.offset(1);
                self.v = self.v.offset(1);
                Some((k, v))
            }
        } else {
            None
        }
    }
}

pub struct ITextKeysIter<'a> {
    pub(crate) k: *mut *mut i8,
    pub(crate) l: *mut *mut i8,
    pub(crate) t: *mut *mut i8,
    pub(crate) s: *mut *mut i8,
    pub(crate) n: usize,
    pub(crate) _p: PhantomData<&'a str>,
}

/// Invalid encoding truncates the strings
impl<'a> Iterator for ITextKeysIter<'a> {
    type Item = (&'a str, &'a str, &'a str, &'a str);
    fn next(&mut self) -> Option<Self::Item> {
        if self.n > 0 {
            unsafe {
                debug_assert!(!(*self.k).is_null()); let k = CStr::from_ptr(*self.k);
                debug_assert!(!(*self.l).is_null()); let l = CStr::from_ptr(*self.l);
                debug_assert!(!(*self.t).is_null()); let t = CStr::from_ptr(*self.t);
                debug_assert!(!(*self.s).is_null()); let s = CStr::from_ptr(*self.s);
                self.n -= 1;
                self.k = self.k.offset(1);
                self.l = self.l.offset(1);
                self.t = self.t.offset(1);
                self.s = self.s.offset(1);
                Some((
                    cstr_to_str(k),
                    cstr_to_str(l),
                    cstr_to_str(t),
                    cstr_to_str(s)))
            }
        } else {
            None
        }
    }
}

fn cstr_to_str(s: &CStr) -> &str {
    match s.to_str() {
        Ok(s) => s,
        Err(e) => {
            std::str::from_utf8(&s.to_bytes()[0..e.valid_up_to()]).unwrap()
        }
    }
}

pub struct ChunksIter<'a> {
    pub(crate) data: &'a [u8],
}

impl<'a> Iterator for ChunksIter<'a> {
    type Item = ChunkRef<'a>;
    fn next(&mut self) -> Option<Self::Item> {
        let header_len = 12;
        if self.data.len() < header_len {
            return None;
        }

        let len = rustimpl::lodepng_chunk_length(self.data);
        if self.data.len() < len + header_len {
            return None;
        }
        let c = ChunkRef::new(&self.data[0..len + header_len]);
        self.data = rustimpl::lodepng_chunk_next(self.data);
        Some(c)
    }
}