feat: 简单实现弹幕功能

lib/pages/danmaku/controller.dart

@@ -0,0 +1,64 @@
+import 'package:pilipala/http/danmaku.dart';
+import 'package:pilipala/models/danmaku/dm.pb.dart';
+import 'package:pilipala/plugin/pl_player/index.dart';
+
+class PlDanmakuController {
+  PlDanmakuController(this.cid, this.playerController);
+  final int cid;
+  final PlPlayerController playerController;
+  late Duration videoDuration;
+  // 按 6min 分段
+  int segCount = 0;
+  List<DmSegMobileReply> dmSegList = [];
+  int currentSegIndex = 0;
+  int currentDmIndex = 0;
+
+  void calcSegment() {
+    segCount = (videoDuration.inSeconds / (60 * 6)).ceil();
+  }
+
+  Future<List<DmSegMobileReply>> queryDanmaku() async {
+    dmSegList.clear();
+    for (int segIndex = 1; segIndex <= segCount; segIndex++) {
+      DmSegMobileReply result =
+          await DanmakaHttp.queryDanmaku(cid: cid, segmentIndex: segIndex);
+      if (result.elems.isNotEmpty) {
+        result.elems.sort((a, b) => (a.progress).compareTo(b.progress));
+        dmSegList.add(result);
+      }
+    }
+    if (dmSegList.isNotEmpty) {
+      findClosestPositionIndex(playerController.position.value.inMilliseconds);
+    }
+    return dmSegList;
+  }
+
+  /// 查询当前最接近的弹幕
+  void findClosestPositionIndex(int position) {
+    int segIndex = (position / (6 * 60 * 1000)).ceil() - 1;
+    if (segIndex < 0) segIndex = 0;
+    List elems = dmSegList[segIndex].elems;
+
+    if (segIndex < dmSegList.length) {
+      int left = 0;
+      int right = elems.length;
+
+      while (left < right) {
+        int mid = (right + left) ~/ 2;
+        var midPosition = elems[mid].progress;
+
+        if (midPosition >= position) {
+          right = mid;
+        } else {
+          left = mid + 1;
+        }
+      }
+
+      currentSegIndex = segIndex;
+      currentDmIndex = right;
+    } else {
+      currentSegIndex = segIndex;
+      currentDmIndex = 0;
+    }
+  }
+}