Add 256 color support

ansi.test.ts

@@ -1,4 +1,4 @@
-import { AnsiTerminalDisplay } from "./ansi.ts";
+import { AnsiColorMode, AnsiTerminalDisplay } from "./ansi.ts";
 import { Buffer, describe, expect, it } from "./testing.ts";
 
 describe(AnsiTerminalDisplay, () => {
@@ -9,17 +9,34 @@ describe(AnsiTerminalDisplay, () => {
     checkSequence(stdout, "![2J");
   });
 
-  it("writes colored characters", async () => {
+  it("writes truecolor characters", async () => {
     const stdout = new Buffer();
     const display = new AnsiTerminalDisplay(stdout);
     await display.setupPalette([
       { r: 0.0, g: 0.0, b: 0.0 },
       { r: 0.5, g: 0.1, b: 1.0 },
-    ]);
+    ], AnsiColorMode.TRUECOLOR);
     await display.setChar({ x: 0, y: 0 }, { ch: "$", fg: 1, bg: 0 });
     checkSequence(stdout, "![38;2;128;26;255m![48;2;0;0;0m![1;1H$");
   });
 
+  it("falls back to 256 colors", async () => {
+    const stdout = new Buffer();
+    const display = new AnsiTerminalDisplay(stdout);
+    const palette = await display.setupPalette([
+      { r: 0.0, g: 0.0, b: 0.0 },
+    ], AnsiColorMode.COLORS256);
+    await display.setChar({ x: 0, y: 0 }, { ch: "a", fg: 0, bg: 1 });
+    await display.setChar({ x: 0, y: 0 }, { ch: "b", fg: 2, bg: 3 });
+    checkSequence(stdout, "![38;5;0m![48;5;1m![1;1Ha![38;5;2m![48;5;3m![1;1Hb");
+
+    expect(palette[0]).toEqual({ r: 0, g: 0, b: 0 });
+    expect(palette[3]).toEqual({ r: 0.5, g: 0.5, b: 0 });
+    expect(palette[14]).toEqual({ r: 0, g: 1, b: 1 });
+    expect(palette[67]).toEqual({ r: 0.2, g: 0.4, b: 0.6 });
+    expect(palette[234]).toEqual({ r: 0.12, g: 0.12, b: 0.12 });
+  });
+
   it("moves the cursor only when needed", async () => {
     const stdout = new Buffer();
     const display = new AnsiTerminalDisplay(stdout);
@@ -31,6 +48,25 @@ describe(AnsiTerminalDisplay, () => {
     await display.setChar({ x: 0, y: 2 }, { ch: "e", fg: 0, bg: 0 });
     checkSequence(stdout, "![1;1Hab![1;4Hcd![3;1He");
   });
+
+  it("changes colors only when needed", async () => {
+    const stdout = new Buffer();
+    const display = new AnsiTerminalDisplay(stdout);
+    display.forceSize({ w: 10, h: 1 });
+    await display.setupPalette([
+      { r: 0.0, g: 0.0, b: 0.0 },
+    ], AnsiColorMode.COLORS256);
+    await display.setChar({ x: 0, y: 0 }, { ch: "a", fg: 1, bg: 0 });
+    await display.setChar({ x: 1, y: 0 }, { ch: "b", fg: 1, bg: 0 });
+    await display.setChar({ x: 2, y: 0 }, { ch: "c", fg: 2, bg: 0 });
+    await display.setChar({ x: 3, y: 0 }, { ch: "d", fg: 0, bg: 2 });
+    await display.setChar({ x: 4, y: 0 }, { ch: "e", fg: 0, bg: 2 });
+    await display.setChar({ x: 5, y: 0 }, { ch: "f", fg: 0, bg: 3 });
+    checkSequence(
+      stdout,
+      "![38;5;1m![48;5;0m![1;1Hab![38;5;2mc![38;5;0m![48;5;2mde![48;5;3mf",
+    );
+  });
 });
 
 function checkSequence(buffer: Buffer, expected: string) {

ansi.ts

@@ -1,6 +1,12 @@
 import { BufferLocation, BufferSize, Char, Color } from "./base.ts";
 import { Display } from "./display.ts";
 
+export enum AnsiColorMode {
+  AUTODETECT,
+  COLORS256,
+  TRUECOLOR,
+}
+
 /**
  * ANSI terminal display
  */
@@ -25,16 +31,36 @@ export class AnsiTerminalDisplay implements Display {
     };
   }
 
-  async setupPalette(colors: readonly Color[]): Promise<readonly Color[]> {
-    // TODO handle not fully rgb compatible terminals
-    const cr = (x: number) => Math.round(x * 255);
-    this.palette_bg = colors.map((col) =>
-      escape(`[48;2;${cr(col.r)};${cr(col.g)};${cr(col.b)}m`)
-    );
-    this.palette_fg = colors.map((col) =>
-      escape(`[38;2;${cr(col.r)};${cr(col.g)};${cr(col.b)}m`)
-    );
-    return colors;
+  async setupPalette(
+    colors: readonly Color[],
+    mode = AnsiColorMode.AUTODETECT,
+  ): Promise<readonly Color[]> {
+    if (mode == AnsiColorMode.AUTODETECT) {
+      const colorterm = Deno.env.get("COLORTERM");
+      if (colorterm?.search(/truecolor|24bit/)) {
+        mode = AnsiColorMode.TRUECOLOR;
+      } else {
+        mode = AnsiColorMode.COLORS256;
+      }
+    }
+
+    if (mode == AnsiColorMode.TRUECOLOR) {
+      // True color is supported, use the request palette as-is
+      const cr = (x: number) => Math.round(x * 255);
+      this.palette_bg = colors.map((col) =>
+        escape(`[48;2;${cr(col.r)};${cr(col.g)};${cr(col.b)}m`)
+      );
+      this.palette_fg = colors.map((col) =>
+        escape(`[38;2;${cr(col.r)};${cr(col.g)};${cr(col.b)}m`)
+      );
+      return colors;
+    } else {
+      // True color not supported, fallback to 256-colors
+      const result = get256Colors();
+      this.palette_bg = result.map((_, idx) => escape(`[48;5;${idx}m`));
+      this.palette_fg = result.map((_, idx) => escape(`[38;5;${idx}m`));
+      return result;
+    }
   }
 
   async clear(): Promise<void> {
@@ -88,4 +114,36 @@ function escape(sequence: string): Uint8Array {
   return new Uint8Array([0x1B, ...new TextEncoder().encode(sequence)]);
 }
 
+function get256Colors(): readonly Color[] {
+  const result: Color[] = [
+    { r: 0, g: 0, b: 0 },
+    { r: 0.5, g: 0, b: 0 },
+    { r: 0, g: 0.5, b: 0 },
+    { r: 0.5, g: 0.5, b: 0 },
+    { r: 0, g: 0, b: 0.5 },
+    { r: 0.5, g: 0, b: 0.5 },
+    { r: 0, g: 0.5, b: 0.5 },
+    { r: 0.75, g: 0.75, b: 0.75 },
+    { r: 0.5, g: 0.5, b: 0.5 },
+    { r: 1, g: 0, b: 0 },
+    { r: 0, g: 1, b: 0 },
+    { r: 1, g: 1, b: 0 },
+    { r: 0, g: 0, b: 1 },
+    { r: 1, g: 0, b: 1 },
+    { r: 0, g: 1, b: 1 },
+    { r: 1, g: 1, b: 1 },
+  ];
+  for (let r = 0; r < 6; r++) {
+    for (let g = 0; g < 6; g++) {
+      for (let b = 0; b < 6; b++) {
+        result.push({ r: r / 5, g: g / 5, b: b / 5 });
+      }
+    }
+  }
+  for (let l = 0; l < 24; l++) {
+    result.push({ r: (l + 1) / 25, g: (l + 1) / 25, b: (l + 1) / 25 });
+  }
+  return result;
+}
+
 const CLEAR = escape("[2J");

config/run.flags

@@ -1 +1 @@
---allow-env --unstable
+--unstable --allow-env=CWD,COLORTERM

ui.test.ts

@@ -16,6 +16,24 @@ describe(TextUI, () => {
     await ui.flush();
     expect(display.last).toEqual({ ch: "x", bg: 0, fg: 1 });
   });
+
+  it("finds the best match for a color in a limited palette", async () => {
+    const app_palette = [
+      { r: 0.0, g: 0.0, b: 1.0 },
+      { r: 0.0, g: 0.0, b: 0.0 },
+    ];
+    const display_palette = [
+      { r: 1.0, g: 1.0, b: 1.0 },
+      { r: 0.1, g: 0.2, b: 0.8 },
+      { r: 0.1, g: 0.2, b: 0.1 },
+    ];
+    const display = new PaletteTestDisplay(display_palette);
+    const ui = new TextUI(display);
+    await ui.init(app_palette);
+    ui.drawing.color(0, 1).text("x", { x: 0, y: 0 });
+    await ui.flush();
+    expect(display.last).toEqual({ ch: "x", bg: 2, fg: 1 });
+  });
 });
 
 class PaletteTestDisplay implements Display {

ui.ts

@@ -5,6 +5,7 @@ import {
   Color,
   PaletteMap,
 } from "./base.ts";
+import { cmp } from "./deps.ts";
 import { Display } from "./display.ts";
 
 /**
@@ -65,14 +66,58 @@ export class TextUI {
     palette: UIPalette,
   ): Promise<PaletteMap> {
     // get the colors supported by display
-    const allcolors = palette
-      .map((c): Color[] => Array.isArray(c) ? c : [c])
-      .reduce((acc, val) => acc.concat(val), []);
-    const supported = await this.display.setupPalette(allcolors);
+    const app_colors = palette.map((c): Color[] => Array.isArray(c) ? c : [c]);
+    const all_colors = app_colors.reduce((acc, val) => acc.concat(val), []);
+    const display_colors = await this.display.setupPalette(all_colors);
 
-    // TODO find the best color mapping for each source color
+    // rank all supported colors by proximity to each app color
+    let ranked: {
+      color: Color;
+      idx: number;
+      penalty: number;
+      matches: { color: Color; idx: number; distance: number }[];
+    }[] = [];
+    app_colors.forEach((colors, idx) => {
+      colors.forEach((color, alt) => {
+        ranked.push({
+          color,
+          idx,
+          penalty: alt + 1,
+          matches: display_colors.map((display_color, didx) => {
+            return {
+              color: display_color,
+              idx: didx,
+              distance: colorDistance(color, display_color),
+            };
+          }).sort(cmp({ key: (info) => info.distance })),
+        });
+      });
+    });
 
-    return palette.map((_, idx) => idx);
+    // TODO negatively score colors too much near previously chosen ones
+
+    // find the best color mapping for each source color
+    const result = palette.map(() => -1);
+    while (ranked.length > 0) {
+      ranked.sort(
+        cmp({ key: (info) => info.matches[0].distance * info.penalty }),
+      );
+
+      const best = ranked[0];
+      const app_idx = best.idx;
+      const display_idx = best.matches[0].idx;
+      result[app_idx] = display_idx;
+
+      for (const color of ranked) {
+        color.matches = color.matches.filter((match) =>
+          match.idx !== display_idx
+        );
+      }
+      ranked = ranked.filter((color) =>
+        color.idx !== app_idx && color.matches.length > 0
+      );
+    }
+    return result;
   }
 }
 
@@ -87,3 +132,17 @@ export class TextUI {
  * array of accepted alternatives, with decreasing priority.
  */
 export type UIPalette = ReadonlyArray<Color | ReadonlyArray<Color>>;
+
+function colorDistance(e1: Color, e2: Color): number {
+  /*return (e2.r - e1.r) * (e2.r - e1.r) +
+    (e2.g - e1.g) * (e2.g - e1.g) +
+    (e2.b - e1.b) * (e2.b - e1.b);*/
+  const c = (x: number) => Math.round(x * 255);
+  const rmean = (c(e1.r) + c(e2.r)) / 2;
+  const r = c(e1.r) - c(e2.r);
+  const g = c(e1.g) - c(e2.g);
+  const b = c(e1.b) - c(e2.b);
+  return Math.sqrt(
+    (((512 + rmean) * r * r) >> 8) + 4 * g * g + (((767 - rmean) * b * b) >> 8),
+  );
+}