Add an image format type

src/ansel.ex

@@ -1,14 +1,6 @@
 defmodule Ansel do
   alias Vix.Vips.{Image, Operation}
 
-  def from_bit_array(bin) do
-    with {:ok, %Image{} = img} <- Image.new_from_buffer(bin) do
-      {:ok, img}
-    else
-      {:error, reason} -> {:error, reason}
-    end
-  end
-
   def write_to_file(img, path) do
     save_path = Path.expand(path)
 
@@ -26,10 +18,6 @@ defmodule Ansel do
     Operation.composite2(base_image, overlay_image, :VIPS_BLEND_MODE_OVER, x: l, y: t)
   end
 
-  def extract_area(image, x, y, w, h) do
-    Operation.extract_area(image, x, y, w, h)
-  end
-
   def new_image(height, width, background) do
     case Operation.black(height, width, bands: 3) do
       {:ok, img} ->
@@ -39,8 +27,4 @@ defmodule Ansel do
         {:error, reason}
     end
   end
-
-  def resize(img, scale) do
-    Operation.resize(img, scale)
-  end
 end

src/ansel.gleam

@@ -1,39 +1,23 @@
 import ansel/bounding_box
 import ansel/color
 import gleam/int
-import gleam/io
 import gleam/result
-import simplifile
 import snag
 
-pub fn main() {
-  io.println("Hello from ansel!")
-
-  // let assert Ok(base) =
-  //   simplifile.read_bits("test.jpg")
-  //   |> result.unwrap(<<>>)
-  //   |> from_bit_array
-
-  // let assert Ok(overlay) =
-  //   simplifile.read_bits("ss.png")
-  //   |> result.unwrap(<<>>)
-  //   |> from_bit_array
-
-  // let _ =
-  //   composite_over(base, overlay, 1, 1)
-  //   |> result.map(write(_, "out.jpg"))
-
-  // base
-  // |> extract_area(LTWH(left: 100, top: 100, width: 400, height: 400))
-  // |> result.map(write(_, "out2.jpg"))
-  // |> io.debug
-
-  let assert Ok(bin) = simplifile.read_bits("comp.png")
-
-  let assert Ok(img) = from_bit_array(bin)
+pub type ImageFormat {
+  AVIF(quality: Int)
+  JPG(quality: Int)
+  PNG
+  WEBP(quality: Int)
+}
 
-  extract_area(img, at: bounding_box.LTWH(left: 3, top: 3, width: 6, height: 6))
-  |> result.map(write(_, "extract.png"))
+fn image_format_to_string(format: ImageFormat) -> String {
+  case format {
+    PNG -> ".png"
+    JPG(quality) -> ".jpg[Q=" <> int.to_string(quality) <> "]"
+    WEBP(quality) -> ".webp[Q=" <> int.to_string(quality) <> "]"
+    AVIF(quality) -> ".avif[Q=" <> int.to_string(quality) <> "]"
+  }
 }
 
 pub type Image
@@ -44,11 +28,15 @@ pub fn from_bit_array(bin: BitArray) -> Result(Image, snag.Snag) {
   |> snag.context("Failed to read image from bit array")
 }
 
-@external(erlang, "Elixir.Ansel", "from_bit_array")
+@external(erlang, "Elixir.Vix.Vips.Image", "new_from_buffer")
 fn from_bit_array_ffi(bin: BitArray) -> Result(Image, String)
 
+pub fn to_bit_array(img: Image, format: ImageFormat) -> BitArray {
+  to_bit_array_ffi(img, image_format_to_string(format))
+}
+
 @external(erlang, "Elixir.Ansel", "to_bit_array")
-pub fn to_bit_array(img: Image, format: String) -> BitArray
+fn to_bit_array_ffi(img: Image, format: String) -> BitArray
 
 pub fn new_image(
   width width: Int,
@@ -123,8 +111,12 @@ pub fn resize_by(img: Image, scale scale: Float) -> Result(Image, snag.Snag) {
 @external(erlang, "Elixir.Vix.Vips.Operation", "resize")
 fn resize_ffi(img: Image, scale: Float) -> Result(Image, String)
 
-pub fn write(img: Image, to path: String) -> Result(Nil, snag.Snag) {
-  write_ffi(img, path)
+pub fn write(
+  img: Image,
+  to path: String,
+  in format: ImageFormat,
+) -> Result(Nil, snag.Snag) {
+  write_ffi(img, path <> image_format_to_string(format))
   |> result.map_error(snag.new)
   |> snag.context("Failed to write image to file")
 }

test/ansel_test.gleam

@@ -15,7 +15,7 @@ pub fn new_image_solid_grey_test() {
     simplifile.read_bits("test/resources/solid_grey_6x6.avif")
 
   ansel.new_image(6, 6, color.Grey)
-  |> result.map(ansel.to_bit_array(_, ".avif"))
+  |> result.map(ansel.to_bit_array(_, ansel.AVIF(quality: 100)))
   |> should.equal(Ok(bin))
 }
 
@@ -24,7 +24,7 @@ pub fn new_image_nongrey_test() {
     simplifile.read_bits("test/resources/gleam_lucy_6x6.avif")
 
   ansel.new_image(6, 6, color.GleamLucy)
-  |> result.map(ansel.to_bit_array(_, ".avif"))
+  |> result.map(ansel.to_bit_array(_, ansel.AVIF(quality: 100)))
   |> should.equal(Ok(bin))
 }
 
@@ -33,23 +33,23 @@ pub fn bit_array_avif_round_trip_test() {
     simplifile.read_bits("test/resources/gleam_lucy_6x6.avif")
 
   ansel.from_bit_array(bin)
-  |> result.map(ansel.to_bit_array(_, ".avif"))
+  |> result.map(ansel.to_bit_array(_, ansel.AVIF(quality: 100)))
   |> should.equal(Ok(bin))
 }
 
 pub fn bit_array_jpg_round_trip_test() {
   let assert Ok(bin) = simplifile.read_bits("test/resources/gleam_lucy_6x6.jpg")
 
   ansel.from_bit_array(bin)
-  |> result.map(ansel.to_bit_array(_, ".jpg"))
+  |> result.map(ansel.to_bit_array(_, ansel.JPG(quality: 100)))
   |> should.equal(Ok(bin))
 }
 
 pub fn bit_array_png_round_trip_test() {
   let assert Ok(bin) = simplifile.read_bits("test/resources/gleam_lucy_6x6.png")
 
   ansel.from_bit_array(bin)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(Ok(bin))
 }
 
@@ -58,7 +58,7 @@ pub fn bit_array_webp_round_trip_test() {
     simplifile.read_bits("test/resources/gleam_lucy_6x6.webp")
 
   ansel.from_bit_array(bin)
-  |> result.map(ansel.to_bit_array(_, ".webp"))
+  |> result.map(ansel.to_bit_array(_, ansel.WEBP(quality: 100)))
   |> should.equal(Ok(bin))
 }
 
@@ -73,7 +73,7 @@ pub fn composite_over_test() {
     ansel.new_image(width: 6, height: 6, color: color.GleamNavy)
 
   ansel.composite_over(base, with: new, at_left_position: 1, at_top_position: 1)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(Ok(bin))
 }
 
@@ -99,7 +99,7 @@ pub fn extract_area_test() {
     comp,
     at: bounding_box.LTWH(left: 3, top: 3, width: 6, height: 6),
   )
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(Ok(ext))
 }
 
@@ -124,10 +124,10 @@ pub fn resize_width_down_test() {
     ansel.new_image(width: 6, height: 4, color: color.GleamLucy)
 
   ansel.resize_width_to(img, res: 3)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(
     ansel.new_image(width: 3, height: 2, color: color.GleamLucy)
-    |> result.map(ansel.to_bit_array(_, ".png")),
+    |> result.map(ansel.to_bit_array(_, ansel.PNG)),
   )
 }
 
@@ -136,10 +136,10 @@ pub fn resize_width_up_test() {
     ansel.new_image(width: 6, height: 4, color: color.GleamLucy)
 
   ansel.resize_width_to(img, res: 12)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(
     ansel.new_image(width: 12, height: 8, color: color.GleamLucy)
-    |> result.map(ansel.to_bit_array(_, ".png")),
+    |> result.map(ansel.to_bit_array(_, ansel.PNG)),
   )
 }
 
@@ -148,10 +148,10 @@ pub fn resize_height_down_test() {
     ansel.new_image(width: 6, height: 8, color: color.GleamLucy)
 
   ansel.resize_height_to(img, res: 4)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(
     ansel.new_image(width: 3, height: 4, color: color.GleamLucy)
-    |> result.map(ansel.to_bit_array(_, ".png")),
+    |> result.map(ansel.to_bit_array(_, ansel.PNG)),
   )
 }
 
@@ -160,10 +160,10 @@ pub fn resize_height_up_test() {
     ansel.new_image(width: 6, height: 4, color: color.GleamNavy)
 
   ansel.resize_height_to(img, res: 12)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(
     ansel.new_image(width: 18, height: 12, color: color.GleamNavy)
-    |> result.map(ansel.to_bit_array(_, ".png")),
+    |> result.map(ansel.to_bit_array(_, ansel.PNG)),
   )
 }
 
@@ -172,10 +172,10 @@ pub fn resize_scale_down_test() {
     ansel.new_image(width: 6, height: 4, color: color.GleamLucy)
 
   ansel.resize_by(img, scale: 0.5)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(
     ansel.new_image(width: 3, height: 2, color: color.GleamLucy)
-    |> result.map(ansel.to_bit_array(_, ".png")),
+    |> result.map(ansel.to_bit_array(_, ansel.PNG)),
   )
 }
 
@@ -184,9 +184,9 @@ pub fn resize_scale_up_test() {
     ansel.new_image(width: 6, height: 4, color: color.GleamNavy)
 
   ansel.resize_by(img, scale: 3.0)
-  |> result.map(ansel.to_bit_array(_, ".png"))
+  |> result.map(ansel.to_bit_array(_, ansel.PNG))
   |> should.equal(
     ansel.new_image(width: 18, height: 12, color: color.GleamNavy)
-    |> result.map(ansel.to_bit_array(_, ".png")),
+    |> result.map(ansel.to_bit_array(_, ansel.PNG)),
   )
-}
+}