imghdr

库，用于确定文件或字节流中包含的图像类型，基本上是Python imghdr 模块的克隆。

示例

直接检查文件

# extern crate imghdr;
# fn main() {
match imghdr::from_file("./tests/images/example.png") {
    Ok(Some(imghdr::Type::Png)) => println!("Yep, it is a PNG"),
    Ok(..) => println!("Nope, it is definitely not a PNG"),
    Err(e) => println!("Some error happened: {:?}", e),
}
# }

或检查字节流

# extern crate imghdr;
# use std::fs::File;
# use std::io::{self, Read};
#
# fn main() -> io::Result<()> {
let mut file = File::open("./tests/images/example.jpeg")?;
let mut content: Vec<u8> = vec![];
file.read_to_end(&mut content)?;

match imghdr::from_bytes(&content) {
    Some(imghdr::Type::Jpeg) => println!("And this is a Jpeg"),
    _ => println!("Can a Png, Bmp or other file format"),
}

# Ok(())
# }