opt: sponsor block

lib/common/widgets/pair.dart

@@ -0,0 +1,8 @@
+class Pair<T, R> {
+  Pair({
+    required this.first,
+    required this.second,
+  });
+  T first;
+  R second;
+}

lib/common/widgets/segment_progress_bar.dart

@@ -0,0 +1,49 @@
+import 'package:flutter/material.dart';
+
+class Segment {
+  final double start;
+  final double end;
+  final Color color;
+
+  Segment(this.start, this.end, this.color);
+}
+
+class SegmentProgressBar extends CustomPainter {
+  final double progress;
+  final List<Segment> segmentColors;
+
+  SegmentProgressBar({
+    required this.progress,
+    required this.segmentColors,
+  });
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final paint = Paint()..style = PaintingStyle.fill;
+
+    for (var segment in segmentColors) {
+      paint.color = segment.color;
+      final segmentStart = segment.start * size.width;
+      final segmentEnd = segment.end * size.width;
+      final progressEnd = progress * size.width;
+
+      if (progressEnd < segmentStart) {
+        break;
+      }
+
+      final segmentWidth =
+          (progressEnd < segmentEnd ? progressEnd : segmentEnd) - segmentStart;
+      if (segmentWidth > 0) {
+        canvas.drawRect(
+          Rect.fromLTWH(segmentStart, 0, segmentWidth, size.height),
+          paint,
+        );
+      }
+    }
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) {
+    return true;
+  }
+}