RxJs: Drag and Drop example : add mousedragstart

Question

How to implement a mousedragstart Observable using the Drag and Drop RxJs\'s example.

mousedragstart should be emit before the first

Answer 1

An alternative solution for drag and drop:

let dragDiv = document.getElementById('drag');
let mouseisdown = false;
let startPos;

Observable.fromEvent(dragDiv, "mousedown").subscribe((e) => {
    mouseisdown = true;
    startPos = { x: e.offsetX, y: e.offsetY}
});
Observable.fromEvent(document, "mouseup").subscribe(e => mouseisdown = false); 


Observable
    .fromEvent(document, "mousemove")
    .filter(e => mouseisdown)
    .map((e) => {
        return   {
          left: e.clientX - startPos.x,
          top: e.clientY - startPos.y
        }
    })
    .subscribe( p => {
    dragDiv.style.top = p.top + "px";
    dragDiv.style.left = p.left + "px";
});

The typescript version:

let dragDiv = document.getElementById('drag');
let mouseisdown = false;
let startPos;

Observable.fromEvent(dragDiv, "mousedown").subscribe((e:MouseEvent) => {
    mouseisdown = true;
    startPos = { x: e.offsetX, y: e.offsetY}
});
Observable.fromEvent(document, "mouseup").subscribe(e => mouseisdown = false); 


Observable
    .fromEvent(document, "mousemove")
    .filter(e => mouseisdown)
    .map((e:MouseEvent) => {
        return   {
          left: e.clientX - startPos.x,
          top: e.clientY - startPos.y
        }
    })
    .subscribe( p => {
    dragDiv.style.top = p.top + "px";
    dragDiv.style.left = p.left + "px";
});