brightness adjustment; find closest palette colour; tests

script.js

@@ -6,6 +6,7 @@ import init, {
     load_game,
     load_default_game,
     output,
+    set_brightness,
     set_dither,
     set_room_name,
 } from './pkg/pixsy.js';
@@ -70,6 +71,7 @@ async function run() {
     const buttonNewGame          = el("new");
     const buttonReset            = el("reset");
     const checkboxDither         = el("dither");
+    const inputBrightness        = el("brightness");
     const inputRoomName          = el("room-name");
     const selectPalette          = el("palette");
     const textareaGameDataInput  = el("game-data");
@@ -171,12 +173,18 @@ async function run() {
 
     checkboxDither.addEventListener("change", () => {
         set_dither(checkboxDither.checked);
+        loadPreview();
     });
 
     inputRoomName.addEventListener("change", () => {
         set_room_name(inputRoomName.value);
     });
 
+    inputBrightness.addEventListener("input", () => {
+        set_brightness(inputBrightness.value);
+        loadPreview();
+    });
+
     function addRoom() {
         console.log(add_room());
         textareaGameDataOutput.value = output();

src/lib.rs

@@ -1,3 +1,5 @@
+#![feature(clamp)]
+
 use bitsy_parser::game::Game;
 use bitsy_parser::image::Image;
 use bitsy_parser::tile::Tile;
@@ -15,6 +17,7 @@ struct State {
     room_name:  Option<String>,
     palette:    Option<String>,
     dither:     bool,
+    brightness: i32,
 }
 
 lazy_static! {
@@ -25,6 +28,7 @@ lazy_static! {
             room_name:  None,
             palette:    None,
             dither:     true,
+            brightness: 0,
         }
     );
 }
@@ -117,6 +121,12 @@ pub fn set_room_name(room_name: String) {
     }
 }
 
+#[wasm_bindgen]
+pub fn set_brightness(brightness: i32) {
+    let mut state = STATE.lock().unwrap();
+    state.brightness = brightness;
+}
+
 #[wasm_bindgen]
 pub fn get_palettes() -> String {
     let state = STATE.lock().unwrap();
@@ -146,15 +156,54 @@ fn image_to_base64(image: &DynamicImage) -> String {
     format!("data:image/png;base64,{}", base64::encode(&bytes))
 }
 
-fn render_preview(image: &DynamicImage) -> DynamicImage {
+fn colour_difference(compare: image::Rgba<u8>, other: &bitsy_parser::Colour) -> u32 {
-    let image = image.clone();
+    let diff_red  = (compare[0] as i16 - other.red   as i16).abs();
-    let image = image.grayscale();
+    let diff_green= (compare[1] as i16 - other.green as i16).abs();
+    let diff_blue = (compare[2] as i16 - other.blue  as i16).abs();
+
+    (diff_red + diff_green + diff_blue) as u32
+}
+
+fn closest_colour(compare: image::Rgba<u8>, colours: &[bitsy_parser::Colour]) -> image::Rgba<u8> {
+    let diff_background = colour_difference(compare, &colours[0]);
+    let diff_foreground = colour_difference(compare, &colours[1]);
+
+    if diff_foreground <= diff_background {
+        image::Rgba::from([colours[1].red, colours[1].green, colours[1].blue, 255])
+    } else {
+        image::Rgba::from([colours[0].red, colours[0].green, colours[0].blue, 255])
+    }
+}
+
+fn adjust_brightness(pixel: &mut image::Rgba<u8>, state: &State) -> image::Rgba<u8> {
+    pixel[0] = (pixel[0] as i32 + state.brightness).clamp(0, 255) as u8;
+    pixel[1] = (pixel[1] as i32 + state.brightness).clamp(0, 255) as u8;
+    pixel[2] = (pixel[2] as i32 + state.brightness).clamp(0, 255) as u8;
+
+    *pixel
+}
+
+fn render_preview(state: &State) -> DynamicImage {
+    let image = state.image.as_ref().unwrap().clone();
+    let mut preview = image.clone();
 
     // todo dither
 
     // todo convert to palette colours
 
-    image
+    // get background and foreground colours from palette
+    let colours = &state.game.as_ref().unwrap().palettes
+        .iter()
+        .find(|palette| &palette.id == state.palette.as_ref().unwrap())
+        .unwrap()
+        .colours[0..2];
+
+    for (x, y, mut pixel) in image.pixels() {
+        // is pixel closer to background or foreground?
+        preview.put_pixel(x, y, closest_colour(adjust_brightness(&mut pixel, &state), colours));
+    }
+
+    preview
 }
 
 #[wasm_bindgen]
@@ -162,7 +211,7 @@ pub fn get_preview() -> String {
     let state = STATE.lock().unwrap();
 
     match &state.image.is_some() {
-        true  => image_to_base64(&render_preview(state.image.as_ref().unwrap())),
+        true  => image_to_base64(&render_preview(&state)),
         false => "".to_string(),
     }
 }
@@ -238,6 +287,7 @@ pub fn output() -> String {
 #[cfg(test)]
 mod test {
     use crate::{add_room, load_image, load_default_game, output, get_preview};
+    use image::Rgba;
 
     #[test]
     fn image_to_base64() {
@@ -247,6 +297,70 @@ mod test {
         assert_eq!(output, expected);
     }
 
+    #[test]
+    fn colour_difference_none() {
+        let output = crate::colour_difference(
+            Rgba::from([255; 4]),
+            &bitsy_parser::Colour {
+                red: 255,
+                green: 255,
+                blue: 255
+            }
+        );
+        assert_eq!(output, 0);
+    }
+
+    #[test]
+    fn colour_difference_some() {
+        let output = crate::colour_difference(
+            Rgba::from([255; 4]),
+            &bitsy_parser::Colour {
+                red:   254,
+                green: 255,
+                blue:  255
+            }
+        );
+        assert_eq!(output, 1);
+    }
+
+    #[test]
+    fn colour_difference_some_2() {
+        let output = crate::colour_difference(
+            Rgba::from([254; 4]),
+            &bitsy_parser::Colour {
+                red:   254,
+                green: 255,
+                blue:  254
+            }
+        );
+        assert_eq!(output, 1);
+    }
+
+    #[test]
+    fn colour_difference_max() {
+        let expected = 255 * 3;
+
+        let output = crate::colour_difference(
+            Rgba::from([0; 4]),
+            &bitsy_parser::Colour {
+                red:   255,
+                green: 255,
+                blue:  255
+            }
+        );
+        assert_eq!(output, expected);
+
+        let output = crate::colour_difference(
+            Rgba::from([255; 4]),
+            &bitsy_parser::Colour {
+                red:   0,
+                green: 0,
+                blue:  0
+            }
+        );
+        assert_eq!(output, expected);
+    }
+
     #[test]
     fn get_palettes() {
         load_default_game();