feat: 直播弹幕

lib/utils/binary_writer.dart

@@ -0,0 +1,117 @@
+import 'dart:typed_data';
+
+class BinaryWriter {
+  List<int> buffer;
+  int position = 0;
+  BinaryWriter(this.buffer);
+  int get length => buffer.length;
+
+  void writeBytes(List<int> list) {
+    buffer.addAll(list);
+    position += list.length;
+  }
+
+  void writeInt(int value, int len, {Endian endian = Endian.big}) {
+    var bytes = _createByteData(len);
+    switch (len) {
+      case 1:
+        bytes.setUint8(0, value.toUnsigned(8));
+        break;
+      case 2:
+        bytes.setInt16(0, value, endian);
+        break;
+      case 4:
+        bytes.setInt32(0, value, endian);
+        break;
+      case 8:
+        bytes.setInt64(0, value, endian);
+        break;
+      default:
+        throw ArgumentError('Invalid length for writeInt: $len');
+    }
+    _addBytesToBuffer(bytes, len);
+  }
+
+  void writeDouble(double value, int len, {Endian endian = Endian.big}) {
+    var bytes = _createByteData(len);
+    switch (len) {
+      case 4:
+        bytes.setFloat32(0, value, endian);
+        break;
+      case 8:
+        bytes.setFloat64(0, value, endian);
+        break;
+      default:
+        throw ArgumentError('Invalid length for writeDouble: $len');
+    }
+    _addBytesToBuffer(bytes, len);
+  }
+
+  ByteData _createByteData(int len) {
+    var b = Uint8List(len).buffer;
+    return ByteData.view(b);
+  }
+
+  void _addBytesToBuffer(ByteData bytes, int len) {
+    buffer.addAll(bytes.buffer.asUint8List());
+    position += len;
+  }
+}
+
+class BinaryReader {
+  Uint8List buffer;
+  int position = 0;
+  BinaryReader(this.buffer);
+  int get length => buffer.length;
+
+  int read() {
+    return buffer[position++];
+  }
+
+  int readInt(int len, {Endian endian = Endian.big}) {
+    var bytes = _getBytes(len);
+    var data = ByteData.view(bytes.buffer);
+    switch (len) {
+      case 1:
+        return data.getUint8(0);
+      case 2:
+        return data.getInt16(0, endian);
+      case 4:
+        return data.getInt32(0, endian);
+      case 8:
+        return data.getInt64(0, endian);
+      default:
+        throw ArgumentError('Invalid length for readInt: $len');
+    }
+  }
+
+  int readByte({Endian endian = Endian.big}) => readInt(1, endian: endian);
+  int readShort({Endian endian = Endian.big}) => readInt(2, endian: endian);
+  int readInt32({Endian endian = Endian.big}) => readInt(4, endian: endian);
+  int readLong({Endian endian = Endian.big}) => readInt(8, endian: endian);
+
+  Uint8List readBytes(int len) {
+    var bytes = _getBytes(len);
+    return bytes;
+  }
+
+  double readFloat(int len, {Endian endian = Endian.big}) {
+    var bytes = _getBytes(len);
+    var data = ByteData.view(bytes.buffer);
+    switch (len) {
+      case 4:
+        return data.getFloat32(0, endian);
+      case 8:
+        return data.getFloat64(0, endian);
+      default:
+        throw ArgumentError('Invalid length for readFloat: $len');
+    }
+  }
+
+  Uint8List _getBytes(int len) {
+    var bytes =
+        Uint8List.fromList(buffer.getRange(position, position + len).toList());
+    position += len;
+    return bytes;
+  }
+}