From 5d5684903ea0228fc0fcfa021f6a6ab9b4b2a2bb Mon Sep 17 00:00:00 2001
From: Andrew Dirksen <andrew@dirksen.com>
Date: Wed, 1 Mar 2023 17:47:17 -0800
Subject: [PATCH 1/2] Add constructors for `Pixel` so users can use the
 `SixelSerializer`. fixes https://github.com/zellij-org/sixel-image/issues/1

---
 Cargo.toml   |  5 +++++
 src/lib.rs   | 11 ++++++++++
 src/tests.rs | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index d43706f..3f5d755 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,3 +9,8 @@ edition = "2021"
 
 [dependencies]
 sixel-tokenizer = "0.1.0"
+
+[dev-dependencies]
+image = "0.24.5"
+itertools = "0.10.5"
+
diff --git a/src/lib.rs b/src/lib.rs
index 99e14d9..2e28045 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -91,6 +91,17 @@ pub struct Pixel {
     color: u16, 
 }
 
+impl Pixel {
+    pub fn new(color: u16) -> Self {
+        Pixel { on: true, color }
+    }
+
+    pub const OFF: Pixel = Pixel {
+        on: false,
+        color: 0,
+    };
+}
+
 impl fmt::Debug for Pixel {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         if self.on {
diff --git a/src/tests.rs b/src/tests.rs
index 545f2a7..2eeee8d 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -1,4 +1,4 @@
-use crate::SixelImage;
+use crate::{Pixel, SixelColor, SixelImage, SixelSerializer};
 
 fn remove_whitespace(s: &str) -> String {
     let mut s = s.to_string();
@@ -236,3 +236,58 @@ fn corrupted_image() {
     ";
     assert!(SixelImage::new(sample.as_bytes()).is_err());
 }
+
+#[test]
+fn img_to_sixel() {
+    let img = image::RgbaImage::from_fn(64, 64, |x, y| {
+        image::Rgba([
+            ((x + 128) % u8::MAX as u32) as u8,
+            ((y + 128) % u8::MAX as u32) as u8,
+            (u8::MAX / 2) as u8,
+            255,
+        ])
+    });
+    println!("{}", render_sixel(&img)); // run with `cargo test -- --nocapture` to see the output
+}
+
+fn render_sixel(img: &image::RgbaImage) -> String {
+    use std::collections::{BTreeMap, HashMap, HashSet};
+
+    use itertools::Itertools;
+
+    let colors: HashMap<[u8; 3], u16> = img
+        .pixels()
+        .map(|p| [p[0], p[1], p[2]].map(compress))
+        .collect::<HashSet<[u8; 3]>>() // dedup
+        .into_iter()
+        .enumerate()
+        .map(|(i, c)| (c, wrapping_into(i)))
+        .collect();
+
+    let color_registers: BTreeMap<u16, SixelColor> = colors
+        .iter()
+        .map(|(&c, &i)| (i, SixelColor::Rgb(c[0], c[1], c[2])))
+        .collect();
+
+    let pixels: Vec<Vec<Pixel>> = img
+        .pixels()
+        .map(|p| {
+            let c = [p[0], p[1], p[2]].map(compress);
+            Pixel::new(colors[&c])
+        })
+        .chunks(img.width() as usize)
+        .into_iter()
+        .map(|c| c.collect())
+        .collect();
+
+    SixelSerializer::new(&color_registers, &pixels).serialize()
+}
+
+fn wrapping_into(u: usize) -> u16 {
+    (u % u16::MAX as usize) as u16
+}
+
+/// compress a color value from the range [0, 255] to the range [0, 100]
+fn compress(a: u8) -> u8 {
+    (a as u16 * 100 / 255) as u8
+}

From 52f6c1c71f254f6b245c6a14572d6e2401c5ff57 Mon Sep 17 00:00:00 2001
From: Andrew Dirksen <andrew@dirksen.com>
Date: Thu, 2 Mar 2023 09:28:05 -0800
Subject: [PATCH 2/2] remove unnecessary integer cast from test

---
 src/tests.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tests.rs b/src/tests.rs
index 2eeee8d..875724f 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -243,7 +243,7 @@ fn img_to_sixel() {
         image::Rgba([
             ((x + 128) % u8::MAX as u32) as u8,
             ((y + 128) % u8::MAX as u32) as u8,
-            (u8::MAX / 2) as u8,
+            u8::MAX / 2,
             255,
         ])
     });