diff options
author | Silas Bartha <silas@exvacuum.dev> | 2024-05-27 14:20:08 -0400 |
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committer | Silas Bartha <silas@exvacuum.dev> | 2024-05-27 14:20:08 -0400 |
commit | ccb19be9d0e918070029f31a86c7eb546121bd87 (patch) | |
tree | 6192bc514a7ae815a8863a23b4cc59405c18ec37 /src/jpeg | |
parent | d088553bd19c58543b908936ba8bae2bfa877b50 (diff) |
Updated docs
Diffstat (limited to 'src/jpeg')
-rw-r--r-- | src/jpeg/mod.rs | 2 | ||||
-rw-r--r-- | src/jpeg/segment.rs | 81 |
2 files changed, 83 insertions, 0 deletions
diff --git a/src/jpeg/mod.rs b/src/jpeg/mod.rs new file mode 100644 index 0000000..3d6bdc3 --- /dev/null +++ b/src/jpeg/mod.rs @@ -0,0 +1,2 @@ +mod segment; +pub use segment::*; diff --git a/src/jpeg/segment.rs b/src/jpeg/segment.rs new file mode 100644 index 0000000..b20ba3b --- /dev/null +++ b/src/jpeg/segment.rs @@ -0,0 +1,81 @@ +use std::{mem::size_of, usize}; + +use img_parts::jpeg::{markers, Jpeg, JpegSegment}; +use thiserror::Error; + +use crate::codec::Codec; + +/// Codec for storing payload data in JPEG comment (COM) segments. Can store an arbitrary amount of +/// data, as long as the number of comment segments does not exceed u64::MAX. +#[derive(Debug, PartialEq, Eq)] +pub struct JpegSegmentCodec { + /// Index of segment to insert comments at. + pub start_index: usize, +} + +impl Codec for JpegSegmentCodec { + type Carrier = Vec<u8>; + type Payload = Vec<u8>; + type Output = Self::Carrier; + type Error = JpegSegmentError; + + fn encode<C, P>(&self, carrier: C, payload: P) -> Result<Self::Output, Self::Error> + where + C: Into<Self::Carrier>, + P: Into<Self::Payload>, + { + let mut jpeg = match Jpeg::from_bytes(carrier.into().into()) { + Ok(image) => image, + Err(err) => return Err(JpegSegmentError::ParseFailed { inner: err }) + }; + let mut payload_bytes: Self::Carrier = payload.into(); + let segment_count = ((payload_bytes.len() + size_of::<u64>()) as u64).div_ceil((u16::MAX as usize - size_of::<u16>()) as u64); + payload_bytes.splice(0..0, segment_count.to_le_bytes()); + for (index, payload_chunk) in payload_bytes.chunks(u16::MAX as usize - size_of::<u16>()).enumerate() { + let segment = JpegSegment::new_with_contents(markers::COM, payload_chunk.to_vec().into()); + jpeg.segments_mut().insert(self.start_index + index, segment); + } + Ok(jpeg.encoder().bytes().to_vec()) + } + + fn decode<E>(&self, encoded: E) -> Result<(Self::Carrier, Self::Payload), Self::Error> + where + E: Into<Self::Output>, + { + let mut jpeg = match Jpeg::from_bytes(encoded.into().into()) { + Ok(image) => image, + Err(err) => return Err(JpegSegmentError::ParseFailed { inner: err }) + }; + let segment = jpeg.segments_mut().remove(self.start_index); + let segment_bytes = segment.contents(); + let segment_count = u64::from_le_bytes(segment_bytes[0..size_of::<u64>()].try_into().unwrap()) as usize; + let mut payload_vec: Vec<u8> = Vec::with_capacity((u16::MAX as usize - size_of::<u16>()) * segment_count); + payload_vec.extend(segment_bytes[size_of::<u64>()..].to_vec()); + + for _ in 0..segment_count-1 { + let segment = jpeg.segments_mut().remove(self.start_index); + payload_vec.extend(segment.contents()); + } + + Ok((jpeg.encoder().bytes().to_vec(), payload_vec)) + } +} + +impl Default for JpegSegmentCodec { + fn default() -> Self { + Self { + start_index: 3, + } + } +} + +/// Errors thrown by the JPEG segment codec. +#[derive(Error, Debug)] +pub enum JpegSegmentError { + /// Parsing JPEG data failed. + #[error("Failed to parse JPEG data: {inner:?}")] + ParseFailed { + /// Error thrown by parser. + inner: img_parts::Error, + } +} |