Kitty Graphics Protocol in OCaml
anil.recoil.org
terminal
graphics
ocaml
1(** Data Compression
2
3 Specifies compression applied to image data before transmission.
4
5 {2 Protocol Details}
6
7 Compression is specified via the [o] key in the control data:
8 - No [o] key means no compression
9 - [o=z] means zlib (RFC 1950 DEFLATE) compression
10
11 Compression is applied to the raw pixel/PNG data {i before} base64
12 encoding. The terminal decompresses after base64 decoding.
13
14 {2 When to Use Compression}
15
16 Zlib compression is beneficial for:
17 - Large images with repetitive patterns
18 - Screenshots and UI graphics
19 - Images with large solid color regions
20
21 It may not help (or could increase size) for:
22 - Already-compressed PNG data
23 - Photographic images with high entropy
24 - Very small images (compression overhead)
25
26 {2 PNG with Compression}
27
28 When using both [{`Png}] format and [{`Zlib}] compression, the [size]
29 parameter must be specified with the original (uncompressed) PNG size.
30 The terminal needs this to allocate the correct buffer for decompression. *)
31
32type t = [ `None | `Zlib ]
33(** Compression options.
34
35 - [`None] - Raw uncompressed data. No [o=] key is sent.
36 - [`Zlib] - RFC 1950 zlib/DEFLATE compression. Data is compressed
37 before base64 encoding and decompressed by the terminal. *)
38
39val to_char : t -> char option
40(** Convert to protocol character.
41
42 Returns [None] for [`None] (no key sent), or [Some 'z'] for [`Zlib].
43 When [Some c] is returned, [o=c] is added to the control data. *)