Flutter高仿微信-第55篇-群聊-合成群头像

 Flutter高仿微信系列共59篇，从Flutter客户端、Kotlin客户端、Web服务器、数据库表结构、Xmpp即时通讯服务器、视频通话服务器、腾讯云服务器全面讲解。

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/**
 * 处理合并群头像
 * @groupId 群id
 * @avatarList 头像列表
 */
static processMergeAvatarImage(String groupId, List avatarList) async {
  if(avatarList.isEmpty){
    return;
  }
  List filePathList = [];
  for(int i = 0; i < avatarList.length; i++){
    if(avatarList[i].isNotEmpty){
      String avatarFilePath = await getCacheFilePath(CommonUtils.getReallyImage(avatarList[i]));
      filePathList.add(avatarFilePath);
    }
  }

  if(filePathList.isEmpty){
    return;
  }

  //合成群头像
  String groupAvatar = await mergeAvatarImage(filePathList);
  LogUtils.d("合并头像地址");
  GroupBean? groupBean = await GroupRepository.getInstance().findGroupByGroupId(groupId);
  if(groupBean != null){
    groupBean?.avatar = groupAvatar;
    GroupRepository.getInstance().updateGroup(groupBean);

    String serverResultAvatar = await UploadUtils.getInstance().uploadGroupAvatar(groupId, groupAvatar);
    //设置服务器头像地址
    groupBean?.avatar = serverResultAvatar;

    //发送消息通知更改群头像
    ChatSendBean chatSendBean = ChatSendBean();
    int contentType = CommonUtils.GROUP_CHAT_TYPE_REFRESH;
    chatSendBean.contentType = contentType;
    chatSendBean.content = serverResultAvatar;
    int id = DateTime.now().millisecondsSinceEpoch;
    String toJid = "${groupId}@conference.wangning";
    String msg = jsonEncode(chatSendBean);
    XmppManager.getInstance().sendGroupMessageWithType(toJid, msg, "${id}", id);
    //GroupRepository.getInstance().updateGroupServer(groupBean);
    LogUtils.d("合并头像更新成功 ${serverResultAvatar}");
  }

}

/**
 * 合并群头像
 * 不管多少个，默认取9个，生成3行3列的图片(从文件读取图片)
 */
static Future mergeAvatarImage(List filePathList) async {

  if(filePathList.isEmpty){
    return "";
  }

  filePathList = _interceptList(filePathList);

  const kCanvasSize = 200.0;
  final Random rd = Random();
  final int numColors = Colors.primaries.length;

  final color = Colors.primaries[rd.nextInt(numColors)];

  final recorder = ui.PictureRecorder();
  final canvas = Canvas(recorder,
      Rect.fromPoints(Offset(0.0, 0.0), Offset(kCanvasSize, kCanvasSize)));

  final stroke = Paint()
    ..color = Colors.grey
    ..style = PaintingStyle.stroke;

  canvas.drawRect(Rect.fromLTWH(0.0, 0.0, kCanvasSize, kCanvasSize), stroke);

  final paint = Paint()
    ..color = color
    ..style = PaintingStyle.fill;

  //3行3列
  for(int i = 0; i < 3; i++){
    for(int j = 0; j < 3; j++){
      String filePath = filePathList[i*3 + j];
      //LogUtils.d("文件路径：${filePath}");
      //加载文件图片
      ui.Image fileImage = await _loadFileImage(filePath);
      //取图片宽高最小的值
      int fileWidth = fileImage.width >= fileImage.height ? fileImage.height : fileImage.width;
      double scale = kCanvasSize/3/fileWidth;

      //显示图片真是的宽高
      double imageWidth = fileWidth * scale;
      double left = j * imageWidth - _getSpaceY(j);
      double top = i * imageWidth - _getSpaceX(i);
      LogUtils.d("file 参数：left = ${left} , top = ${top} , imageWidth = ${imageWidth} , fileWidth = ${fileWidth}, scale = ${scale}  ");
      //移动x
      double dx = j * imageWidth;
      //移动y
      double dy = i * imageWidth;
      canvas.save();
      canvas.translate(dx, dy);
      canvas.scale(scale, scale);

      Rect src = Rect.fromLTWH(left, top , fileWidth.toDouble(), fileWidth.toDouble());
      canvas.drawImageRect(fileImage, src, src, paint);

      canvas.restore();
    }
  }

  final picture = recorder.endRecording();
  final img = await picture.toImage(200, 200);
  final pngBytes = await img.toByteData(format: ImageByteFormat.png);

  String resultFilePath = await _saveMergeGroupAvatar(pngBytes);
  return resultFilePath;
}

//如果超过9个， 截取前面9个，如果少于9个，在里面随机获取补够9个
static List _interceptList(List filePathList){
  List resultFilePathList = [];
  //最多9个
  int maxSize = 9;
  //个数
  int size = filePathList.length;
  if(size >= 9){
    resultFilePathList = filePathList.sublist(0,9);
  } else {
    resultFilePathList = filePathList;
    //还要补多少个
    int repairSize = maxSize - size;
    for(int i = 0; i < repairSize; i++){
      //在现有的列表随机取
      int ran = Random().nextInt(size);
      resultFilePathList.add(filePathList[ran]);
    }
  }
  return resultFilePathList;
}

static int _getSpaceY(int j){
  //纵轴空白
  int spaceY = 0;
  if(j == 1){
    spaceY = 40;
  } else if(j == 2){
    spaceY = 110;
  }
  return spaceY;
}

//横轴空白
static int _getSpaceX(int i){
  //横轴空白
  int spaceX = 0;
  if(i == 1){
    spaceX = 40;
  } else if(i == 2){
    spaceX = 110;
  }

  return spaceX;
}

//从手机加载图片
static Future _loadFileImage(String filePath) async {
  File file = File(filePath);
  final Completer completer = Completer();
  ui.decodeImageFromList(file.readAsBytesSync(), (ui.Image img) {
    return completer.complete(img);
  });
  return completer.future;
}

//从资源文件加载图片
static Future _loadAssetUiImage(String imageAssetPath) async {
  final ByteData data = await rootBundle.load(imageAssetPath);

  final Completer completer = Completer();
  ui.decodeImageFromList(Uint8List.view(data.buffer), (ui.Image img) {
    return completer.complete(img);
  });
  return completer.future;
}

//保存合并群头像
static Future _saveMergeGroupAvatar(ByteData? imgBytes) async {
  String uuid = UUID.getUUID();
  String saveFilePath = await FileUtils.getBaseFile("${uuid}.png");
  File file = File(saveFilePath);
  final pngBytes = imgBytes!.buffer.asUint8List();
  await file.writeAsBytes(pngBytes);
  return saveFilePath;
}