progress

2026-10-07 06:14:07 +00:00 · 2026-10-04 08:53:00 +02:00
parent 86aba8f4b1
commit 9ac2a2b69c
6 changed files with 141 additions and 19 deletions
@@ -0,0 +1,59 @@
+const PALETTE = [
+    '#ff0000',
+    '#0000ff',
+    '#46e646',
+    '#00ccff',
+    '#ff9900',
+    '#ff00ff',
+    '#ffff32',
+    '#288228',
+    '#9933ff',
+    '#50f0be',
+    '#8c645a',
+];
+
+/** GPX style colors are hex digits, with or without the leading `#`. */
+export function normalizeColor(color: string): string {
+    return /^[0-9a-f]{6}$/i.test(color) ? `#${color}` : color;
+}
+
+/**
+ * Picks the base color of each file: the color defined by the file itself if any, otherwise a
+ * palette color, the least used one when the file first shows up. A file keeps its palette color
+ * for its whole lifetime, so that it does not change when style information comes and goes
+ * (edits, undo, redo).
+ */
+export class FileColorAllocator {
+    /** Palette color reserved for each file. */
+    private _reserved = new Map<string, string>();
+    /** Color currently displayed for each file. */
+    private _base = new Map<string, string>();
+
+    /** Updates (and returns) the base color of a file, given the colors defined by its tracks. */
+    resolve(fileId: string, trackColors: (string | undefined)[]): string {
+        const explicit = trackColors.find((color) => color !== undefined);
+        if (explicit === undefined && !this._reserved.has(fileId)) {
+            this._reserved.set(fileId, this.leastUsed());
+        }
+        const color =
+            explicit !== undefined ? normalizeColor(explicit) : this._reserved.get(fileId)!;
+        this._base.set(fileId, color);
+        return color;
+    }
+
+    release(fileId: string) {
+        this._reserved.delete(fileId);
+        this._base.delete(fileId);
+    }
+
+    private leastUsed(): string {
+        const usage = new Map(PALETTE.map((color) => [color, 0]));
+        this._base.forEach((color) => {
+            const count = usage.get(color);
+            if (count !== undefined) {
+                usage.set(color, count + 1);
+            }
+        });
+        return PALETTE.reduce((a, b) => (usage.get(a)! <= usage.get(b)! ? a : b));
+    }
+}