Question

我正在Flutter中处理可拖动对象和拖动目标。我目前在项目中有两个dragtarget，一旦将可拖动对象放到它们上，它们都可以正确响应。但是，一旦完成了从draggable1到dragtarget1的第一次拖动，第二个拖动就带来了一个问题：在将鼠标悬停在dragtagable2上并拖动draggable2的同时，onaccept属性被触发，并且dragtarget2使用dragtarget1的内容构建。我不明白为什么。如果有任何帮助/提示，我将不胜感激！

我制作了一段简短的视频，以直观的方式展示了该问题：https://youtu.be/IJa3oZ_7fw0

这是我的dragtarget代码：

 Widget build(BuildContext context) {
bool isSuccessful = false;
int caughtData;
return SafeArea(
  child: Column(
    children: <Widget>[
      Row(
        children: <Widget>[
          Expanded(
            child: Container(
              height: 70,
              width: 200,
              color: Colors.grey.shade600,
              child: DragTarget<int>(
                builder: (context, List<int> candidateData, rejectedData) {
                  return isSuccessful
                      ? FlatButton(
                          color:
                              chordBrain.chordBank[caughtData].buttoncolor,
                          child:
                              Text(chordBrain.chordBank[caughtData].chord),
                          onPressed: () {
                            playSound(noteBrain.noteBank[caughtData].note1);
                            playSound(noteBrain.noteBank[caughtData].note2);
                            playSound(noteBrain.noteBank[caughtData].note3);
                            playSound(noteBrain.noteBank[caughtData].note4);
                          },
                        )
                      : Container();
                },
                onWillAccept: (int data) {
                  print('$data');
                  return true;
                },
                onAccept: (int data) {
                  print('$data');
                  isSuccessful = true;
                  caughtData = data;
                },
              ),
            ),
          ),
          SizedBox(
            width: 8,
          ),
          Expanded(
            child: Container(
              height: 70,
              width: 200,
              color: Colors.grey.shade600,
              child: DragTarget<int>(
                builder: (context, List<int> candidateData, rejectedData) {
                  return isSuccessful
                      ? FlatButton(
                          color:
                              chordBrain.chordBank[caughtData].buttoncolor,
                          child:
                              Text(chordBrain.chordBank[caughtData].chord),
                          onPressed: () {
                            playSound(noteBrain.noteBank[caughtData].note1);
                            playSound(noteBrain.noteBank[caughtData].note2);
                            playSound(noteBrain.noteBank[caughtData].note3);
                            playSound(noteBrain.noteBank[caughtData].note4);
                          },
                        )
                      : Container();
                },
                onWillAccept: (int data) {
                  print('$data');
                  return true;
                },
                onAccept: (int data) {
                  print('$data');
                  isSuccessful = true;
                  caughtData = data;
                },
              ),
            ),
          ),
        ],
      ),

Answer 1

似乎我找到了一个解决方案，虽然它不是很优雅，但是可以工作。尽管我仍然不明白为什么将我的可拖动对象悬停（而不是放下）在拖动目标上时会触发构建，但是通过使拖动目标彼此之间更加不同来解决了该问题。与其给我的两个拖动目标分配相同的bool和int变量来触发构建小部件，我不给它们唯一的变量：

Widget build(BuildContext context) {
bool isSuccessful = false;
bool isWorking = false;
int caughtData1;
int caughtData2;

布尔值isSuccessful，并且将整数catchData1分配给第一个拖动目标，将isWorking和catchData2分配给第二个拖动目标。我还删除了onWillAccept代码-虽然不确定是否必要。完整代码如下：

Widget build(BuildContext context) {
bool isSuccessful = false;
bool isWorking = false;
int caughtData1;
int caughtData2;

return SafeArea(
  child: Column(
    children: <Widget>[
      Row(
        children: <Widget>[
          Expanded(
            child: Container(
              height: 70,
              color: Colors.grey.shade600,
              child: DragTarget<int>(
                builder: (context, List<int> candidateData, rejectedData) {
                  return isWorking
                      ? FlatButton(
                          color:
                              chordBrain.chordBank[caughtData1].buttoncolor,
                          child:
                              Text(chordBrain.chordBank[caughtData1].chord),
                          onPressed: () {
                            playSound(
                                noteBrain.noteBank[caughtData1].note1);
                            playSound(
                                noteBrain.noteBank[caughtData1].note2);
                            playSound(
                                noteBrain.noteBank[caughtData1].note3);
                            playSound(
                                noteBrain.noteBank[caughtData1].note4);
                          },
                        )
                      : Container();
                },
                onAccept: (int data) {
                  print('$data');
                  caughtData1 = data;
                  isWorking = true;
                },
              ),
            ),
          ),
          SizedBox(
            width: 8,
          ),
          Expanded(
            child: Container(
              height: 70,
              color: Colors.grey.shade600,
              child: DragTarget<int>(
                builder: (context, List<int> candidateData, rejectedData) {
                  return isSuccessful
                      ? FlatButton(
                          color:
                              chordBrain.chordBank[caughtData2].buttoncolor,
                          child:
                              Text(chordBrain.chordBank[caughtData2].chord),
                          onPressed: () {
                            playSound(
                                noteBrain.noteBank[caughtData2].note1);
                            playSound(
                                noteBrain.noteBank[caughtData2].note2);
                            playSound(
                                noteBrain.noteBank[caughtData2].note3);
                            playSound(
                                noteBrain.noteBank[caughtData2].note4);
                          },
                        )
                      : Container();
                },
                onAccept: (int data) {
                  print('$data');
                  caughtData2 = data;
                  isSuccessful = true;
                },
              ),
            ),
          ),
        ],
      ),

将鼠标悬停在Flutter中的Dragtarget上时，可拖动触发错误信息

1 个答案: