Codec.Picture.Jpg.Internal.Types

Macroblock that can be transformed.

Create a new macroblock with the good array size

Type only used to make clear what kind of integer we are carrying Might be transformed into newtype in the future

Size: 1

Type introduced only to avoid some typeclass overlapping problem

Like get from `instance Binary JpgImage`, but without the legacy semi-lazy implementation.

Parses a Scan's ECS (Entropy-Coded Segment, the largest part of compressed image data) from the Get stream.

When this function is called, the parser's offset should be immediately behind the SOS tag.

As described on e.g. https://www.ccoderun.ca/programming/2017-01-31_jpeg/,

To find the next segment after the SOS, you must keep reading until you
find a 0xFF bytes which is not immediately followed by 0x00 (see "byte stuffing")
[or a reset marker's byte: 0xD0 through 0xD7].
Normally, this will be the EOI segment that comes at the end of the file.

where the 0xFF is the next segment's marker. See https://github.com/corkami/formats/blob/master/image/jpeg.md#entropy-coded-segment for more details.

This function returns the ECS, not including the next segment's marker on its trailing end.

Simpler implementation of parseECS to allow an easier understanding of the logic, and to provide a comparison for correctness.

Parses a single frame.

Returns Nothing when we encounter a frame we want to skip.

Parse a list of JpgFrames.

Parse a list of JpgFrameKinds with their corresponding offsets and lengths (not counting the segment and frame markers into the lengths).

Useful for debugging.

Parses forward, returning the first scan header encountered.

Should be used after skipUntilFrames.

Fails parsing when an SOS segment marker (JpgStartOfScan, resulting in JpgScanBlob) is encountered before an SOF segment marker (that results in JpgScans carrying the JpgFrameHeader).