dart - Dart 拖放div

Question

我正在拖放div，我有以下代码:

 void init() {


    ...
    baseWindowTitleDiv.on.mouseDown.add((MouseEvent event) => saveWindowXY(event));
    baseWindowTitleDiv.on.mouseUp.add((MouseEvent event) => stopMoveEvent(event));
    ...        
  }
  void saveWindowXY(MouseEvent event) {
    ...

    document.on.mouseMove.add((MouseEvent event) => runMoveEvent(event));

  }

  void stopMoveEvent(MouseEvent event) {
    print('stopMoveEvent call');    
    document.on.mouseMove.remove((MouseEvent event) => runMoveEvent(event));//does not work!    
  }

  void runMoveEvent(MouseEvent event) {
    ...
  }

我不明白如何从document.on.mouseMove中删除侦听器

完整代码在这里- https://gist.github.com/OZKA/5795352

Answer 1

据我所知，您需要拥有添加事件的句柄，然后使用该句柄将其删除，例如:

var myEvent = (MouseEvent event) => runMoveEvent(event); // store the function in a variable.

void init() {
  document.on.mouseMove.add(myEvent); // refer to the function by name
}


void stopMoveEvent(MouseEvent event) {
  document.on.mouseMove.remove(myEvent); // remove the same function.
}

void runMoveEvent(event) { ... }

您在代码中所做的就是添加一个匿名函数，并删除另一个匿名函数。我认为 http://dartbug.com/144(标记为WontFix)可能提供了更多有关为何无效的详细信息。