RxJs如何处理文档事件

Question

开始使用RxJs.无法找到解决这个问题的方法.我有一个可拖动的控件:

startDrag = rx.Observable.fromEvent(myElem,'mousedown')

现在,因为控件太小mousemove而且mouseup事件应该在文档级别(否则它将不会停止拖动,除非光标正好在元素上)

endDrag = rx.Observable.fromEvent document,'mouseup'

position = startDrag.flatMap ->
   rx.Observable.fromEvent document,'mousemove'
   .map (x)-> x.clientX
   .takeUntil endDrag

现在,当我不再被拖动时,我如何"抓住"正确的时刻(mouseup).你看到订阅的问题endDrag？每次点击任何地方都会触发,而不仅仅是myElem 如何一次检查所有3个属性？它应该只采取那些完全发生在startDrag和之后的document.mouseupsposition

Upd:我的意思是问题不在于移动元素.那部分很容易 - 订阅position,更改元素的CSS.我的问题是 - 我需要检测时刻mouseup并知道被拖动的确切元素(页面上有多个元素).怎么做我不知道.

Answer 1

我已经调整了RxJS repo中提供的拖放示例,以满足您的需要.

显着变化:

• mouseUp听着document.

• 目标元素被添加到返回select.

• 拖动动作在内部处理map并map返回mouseDown事件中目标的元素.

• 通话last后,takeUntil(mouseUp)因此subscribe将只能达到在拖动过程结束(每一次拖动).

工作范例:

function main() {
  var dragTarget = document.getElementById('dragTarget');

  // Get the three major events
  var mouseup = Rx.Observable.fromEvent(document, 'mouseup');
  var mousemove = Rx.Observable.fromEvent(document, 'mousemove');
  var mousedown = Rx.Observable.fromEvent(dragTarget, 'mousedown');


  var mousedrag = mousedown.selectMany(function(md) {

    // calculate offsets when mouse down
    var startX = md.offsetX;
    var startY = md.offsetY;

    // Calculate delta with mousemove until mouseup
    return mousemove.select(function(mm) {
      if (mm.preventDefault) mm.preventDefault();
      else event.returnValue = false;

      return {
        // Include the targeted element
        elem: mm.target,
        pos: {
          left: mm.clientX - startX,
          top: mm.clientY - startY
        }
      };
    })
    .map(function(data) {
      // Update position
      dragTarget.style.top = data.pos.top + 'px';
      dragTarget.style.left = data.pos.left + 'px';

      // Just return the element
      return data.elem;
    })
    .takeUntil(mouseup)
    .last();
  });


  // Here we receive the element when the drag is finished
  subscription = mousedrag.subscribe(function(elem) {
    alert('Drag ended on #' + elem.id);
  });
}
main();

#dragTarget {
  position: absolute;
  width: 20px;
  height: 20px;
  background: #0f0;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/4.0.7/rx.all.min.js"></script>
<div id="dragTarget"></div>