feat: PianoKeys component

app/app/components/chord-diagram/piano-keys.tsx

@@ -0,0 +1,117 @@
+/** Chroma value (0=C … 11=B) for every note name tonal might return */
+const NOTE_CHROMA: Record<string, number> = {
+  'C': 0, 'C#': 1, 'Db': 1,
+  'D': 2, 'D#': 3, 'Eb': 3,
+  'E': 4, 'Fb': 4,
+  'F': 5, 'E#': 5, 'F#': 6, 'Gb': 6,
+  'G': 7, 'G#': 8, 'Ab': 8,
+  'A': 9, 'A#': 10, 'Bb': 10,
+  'B': 11, 'Cb': 11, 'B#': 0,
+};
+
+const WHITE_KEYS = ['C', 'D', 'E', 'F', 'G', 'A', 'B'];
+const WHITE_KEY_W = 14; // px
+const WHITE_KEY_H = 56; // px
+const BLACK_KEY_W = 9;  // px
+const BLACK_KEY_H = 34; // px
+
+/** Left offset (px) of each black key from the left edge of the keyboard */
+const BLACK_KEY_LEFT: Record<string, number> = {
+  'C#': 1 * WHITE_KEY_W - BLACK_KEY_W / 2,
+  'D#': 2 * WHITE_KEY_W - BLACK_KEY_W / 2,
+  'F#': 4 * WHITE_KEY_W - BLACK_KEY_W / 2,
+  'G#': 5 * WHITE_KEY_W - BLACK_KEY_W / 2,
+  'A#': 6 * WHITE_KEY_W - BLACK_KEY_W / 2,
+};
+
+const BLACK_KEY_NAMES = Object.keys(BLACK_KEY_LEFT);
+
+interface Props {
+  /** Note names from tonal, e.g. ["C","E","G"] or ["Ab","C","Eb"] */
+  notes: string[];
+}
+
+export function PianoKeys({ notes }: Props) {
+  const activeChroma = new Set(
+    notes.map((n) => NOTE_CHROMA[n]).filter((c) => c !== undefined)
+  );
+  const totalWidth = WHITE_KEY_W * 7;
+
+  if (notes.length === 0) {
+    return (
+      <div
+        className="flex items-center justify-center text-muted-foreground text-xs"
+        style={{ width: totalWidth, height: WHITE_KEY_H }}
+      >
+        ?
+      </div>
+    );
+  }
+
+  return (
+    <div className="relative inline-block" style={{ width: totalWidth, height: WHITE_KEY_H }}>
+      {/* White keys */}
+      {WHITE_KEYS.map((note, i) => {
+        const active = activeChroma.has(NOTE_CHROMA[note]);
+        return (
+          <div
+            key={note}
+            className="absolute border border-border rounded-b-sm"
+            style={{
+              left: i * WHITE_KEY_W,
+              top: 0,
+              width: WHITE_KEY_W - 1,
+              height: WHITE_KEY_H,
+              background: active ? 'hsl(var(--primary) / 0.15)' : 'white',
+            }}
+          >
+            {active && (
+              <div
+                className="absolute rounded-full bg-primary"
+                style={{
+                  width: 8,
+                  height: 8,
+                  bottom: 6,
+                  left: '50%',
+                  transform: 'translateX(-50%)',
+                }}
+              />
+            )}
+          </div>
+        );
+      })}
+
+      {/* Black keys (rendered on top) */}
+      {BLACK_KEY_NAMES.map((note) => {
+        const chroma = NOTE_CHROMA[note];
+        const active = activeChroma.has(chroma);
+        return (
+          <div
+            key={note}
+            className="absolute z-10 rounded-b-sm"
+            style={{
+              left: BLACK_KEY_LEFT[note],
+              top: 0,
+              width: BLACK_KEY_W,
+              height: BLACK_KEY_H,
+              background: active ? 'hsl(var(--primary))' : '#1a1a1a',
+            }}
+          >
+            {active && (
+              <div
+                className="absolute rounded-full bg-primary-foreground"
+                style={{
+                  width: 6,
+                  height: 6,
+                  bottom: 4,
+                  left: '50%',
+                  transform: 'translateX(-50%)',
+                }}
+              />
+            )}
+          </div>
+        );
+      })}
+    </div>
+  );
+}