Initial commit

.github/workflows/test.yml

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+name: test
+
+on:
+  push:
+    branches:
+      - master
+      - main
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: "26.0.2"
+          gleam-version: "1.2.0"
+          rebar3-version: "3"
+          # elixir-version: "1.15.4"
+      - run: gleam deps download
+      - run: gleam test
+      - run: gleam format --check src test

.gitignore

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+*.beam
+*.ez
+/build
+erl_crash.dump

README.md

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+# pngleam
+
+[![Package Version](https://img.shields.io/hexpm/v/pngleam)](https://hex.pm/packages/pngleam)
+[![Hex Docs](https://img.shields.io/badge/hex-docs-ffaff3)](https://hexdocs.pm/pngleam/)
+
+```sh
+gleam add pngleam
+```
+```gleam
+import pngleam
+
+pub fn main() {
+  [
+    <<0xFF, 0x00, 0x00, 0x00, 0xFF, 0x00, 0x00, 0x00, 0xFF>>,
+    <<0xFF, 0xFF, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0x00, 0xFF>>,
+    <<0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0x80, 0x80, 0x80>>,
+  ]
+  |> gleam_png.from_packed(
+    width: 3,
+    height: 3,
+    color_info: pngleam.rgb_8bit,
+    compression_level: pngleam.default_compression,
+  )
+  |> simplifile.write_bits("img.png", _)
+}
+```
+
+Further documentation can be found at <https://hexdocs.pm/pngleam>.
+
+## Development
+
+```sh
+gleam run   # Run the project
+gleam test  # Run the tests
+gleam shell # Run an Erlang shell
+```

gleam.toml

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+name = "pngleam"
+version = "1.0.0"
+
+description = "PNG image library for Gleam"
+licences = ["AGPL-3.0-only"]
+repository = { type = "github", user = "LilyRose2798", repo = "pngleam" }
+links = [
+  { title = "7Circles Git", href = "https://git.7cs.dev/lily/pngleam" },
+]
+
+[dependencies]
+gleam_stdlib = ">= 0.34.0 and < 2.0.0"
+gzlib = ">= 1.0.0 and < 2.0.0"
+
+[dev-dependencies]
+gleeunit = ">= 1.0.0 and < 2.0.0"

manifest.toml

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+# This file was generated by Gleam
+# You typically do not need to edit this file
+
+packages = [
+  { name = "gleam_stdlib", version = "0.38.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "663CF11861179AF415A625307447775C09404E752FF99A24E2057C835319F1BE" },
+  { name = "gleeunit", version = "1.1.2", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "72CDC3D3F719478F26C4E2C5FED3E657AC81EC14A47D2D2DEBB8693CA3220C3B" },
+  { name = "gzlib", version = "1.0.0", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gzlib", source = "hex", outer_checksum = "EC6A3FAF20B8A707B5A550E1B622785685759991C9D13CFC4AAE8FE34FDDF3B8" },
+]
+
+[requirements]
+gleam_stdlib = { version = ">= 0.34.0 and < 2.0.0" }
+gleeunit = { version = ">= 1.0.0 and < 2.0.0" }
+gzlib = { version = ">= 1.0.0 and < 2.0.0" }

src/pngleam.gleam

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+import gleam/bit_array
+import gleam/list
+import gzlib
+
+pub const no_compression = gzlib.no_compression
+
+pub const min_compression = gzlib.min_compression
+
+pub const max_compression = gzlib.max_compression
+
+pub const default_compression = gzlib.default_compression
+
+pub const compression_level = gzlib.compression_level
+
+pub type ColorType {
+  Greyscale
+  Color
+  Indexed
+  GreyscaleWithAlpha
+  ColorWithAlpha
+}
+
+fn color_type_to_int(color_type: ColorType) -> Int {
+  case color_type {
+    Greyscale -> 0b000
+    Color -> 0b010
+    Indexed -> 0b011
+    GreyscaleWithAlpha -> 0b100
+    ColorWithAlpha -> 0b110
+  }
+}
+
+pub opaque type ColorInfo {
+  ColorInfo(color_type: ColorType, bit_depth: Int)
+}
+
+pub const greyscale_8bit = ColorInfo(Greyscale, 8)
+
+pub const rgb_8bit = ColorInfo(Color, 8)
+
+pub const rgb_16bit = ColorInfo(Color, 16)
+
+pub const rgba_8bit = ColorInfo(ColorWithAlpha, 8)
+
+pub const rgba_16bit = ColorInfo(ColorWithAlpha, 16)
+
+pub fn color_info(
+  color_type color_type: ColorType,
+  bit_depth bit_depth: Int,
+) -> Result(ColorInfo, Nil) {
+  let color_info = Ok(ColorInfo(color_type, bit_depth))
+  case color_type, bit_depth {
+    Greyscale, 1 | Greyscale, 2 | Greyscale, 4 | Greyscale, 8 | Greyscale, 16 ->
+      color_info
+    Color, 8 | Color, 16 -> color_info
+    Indexed, 1 | Indexed, 2 | Indexed, 4 | Indexed, 8 -> color_info
+    GreyscaleWithAlpha, 8 | GreyscaleWithAlpha, 16 -> color_info
+    ColorWithAlpha, 8 | ColorWithAlpha, 16 -> color_info
+    _, _ -> Error(Nil)
+  }
+}
+
+fn chunk_bit_array(data: BitArray) -> List(BitArray) {
+  do_chunk_bit_array(data, []) |> list.reverse
+}
+
+fn do_chunk_bit_array(data: BitArray, chunks: List(BitArray)) -> List(BitArray) {
+  case data {
+    <<chunk:bytes-size(8192), rest:bytes>> ->
+      do_chunk_bit_array(rest, [chunk, ..chunks])
+    chunk -> [chunk, ..chunks]
+  }
+}
+
+fn get_chunk(tag: String, data: BitArray) -> BitArray {
+  let data_size = bit_array.byte_size(data)
+  let tag_bits = <<tag:utf8>>
+  let checksum = gzlib.continue_crc32(gzlib.crc32(tag_bits), data)
+  <<data_size:size(32), tag_bits:bits, data:bits, checksum:size(32)>>
+}
+
+const signature = <<137, "PNG":utf8, "\r\n":utf8, 26, "\n":utf8>>
+
+pub fn from_packed(
+  row_data row_data: List(BitArray),
+  width width: Int,
+  height height: Int,
+  color_info color_info: ColorInfo,
+  compression_level compression_level: gzlib.CompressionLevel,
+) -> BitArray {
+  let ihdr =
+    get_chunk("IHDR", <<
+      width:size(32),
+      height:size(32),
+      color_info.bit_depth:size(8),
+      color_type_to_int(color_info.color_type):size(8),
+      0:size(8),
+      0:size(8),
+      0:size(8),
+    >>)
+  let idats =
+    row_data
+    |> list.map(fn(d) { <<0, d:bits>> })
+    |> bit_array.concat
+    |> gzlib.compress_with_level(compression_level)
+    |> chunk_bit_array
+    |> list.map(get_chunk("IDAT", _))
+    |> bit_array.concat
+  let iend = get_chunk("IEND", <<>>)
+  <<signature:bits, ihdr:bits, idats:bits, iend:bits>>
+}

test/pngleam_test.gleam

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+import gleeunit
+
+pub fn main() {
+  gleeunit.main()
+}