1use std::fs::File;
2use std::io::{BufReader, Result};
3use std::path::PathBuf;
4
5use image::codecs::gif::GifDecoder;
6use image::AnimationDecoder;
7
8/// Returns True if a file is an animated GIF, and False otherwise.
9pub fn is_animated_gif(path: &PathBuf) -> Result<bool> {
10    let file = File::open(path)?;
11
12    let reader = BufReader::new(file);
13    let decoder = GifDecoder::new(reader);
14
15    match decoder {
16        Ok(dc) => Ok(dc.into_frames().count() > 1),
17        _ => Ok(false),
18    }
19}
20
21#[cfg(test)]
22mod test_is_animated_gif {
23    use std::path::PathBuf;
24
25    use super::*;
26
27    #[test]
28    fn a_png_is_not_an_animated_gif() {
29        let p = PathBuf::from("src/tests/blue.png");
30        assert_eq!(is_animated_gif(&p).unwrap(), false);
31    }
32
33    #[test]
34    fn a_static_gif_is_not_an_animated_gif() {
35        let p = PathBuf::from("src/tests/static.gif");
36        assert_eq!(is_animated_gif(&p).unwrap(), false);
37    }
38
39    #[test]
40    fn an_animated_gif_is_animated() {
41        let p = PathBuf::from("src/tests/animated_squares.gif");
42        assert_eq!(is_animated_gif(&p).unwrap(), true);
43    }
44
45    #[test]
46    fn a_non_image_is_not_animated_gif() {
47        let p = PathBuf::from("Cargo.toml");
48        assert_eq!(is_animated_gif(&p).unwrap(), false);
49    }
50
51    #[test]
52    fn a_file_which_doesnt_exist_is_an_error() {
53        let p = PathBuf::from("does_not_exist.txt");
54        assert!(is_animated_gif(&p).is_err());
55    }
56}