在UIWebView / WKWebView中启用拖动

Question

Trello, on the desktop website, allows you to drag elements around like this:

However, when using Safari on iOS, this doesn't work.

It either selects the element or pops up a sheet.

If I present this in a UIWebView or WKWebView, can I make the WebView act more like desktop Safari, so that I can drag the elements around?

I've discovered I can stop various iOS actions by sending the webview some javascript:

// stop selection
webView.stringByEvaluatingJavaScriptFromString("document.documentElement.style.webkitUserSelect='none';")

// stop copy/paste etc
webView.stringByEvaluatingJavaScriptFromString("document.documentElement.style.webkitTouchCallout='none';")

// stop loupe
webView.stringByEvaluatingJavaScriptFromString("document.body.style.webkitUserSelect='none';")

But this still doesn't let me drag elements around.

Is there a solution?

(I know there is a Trello app, I'm just curious if this is possible with WebView)

Answer 1

Trello, on the desktop website, allows you to drag elements around..

However, when using Safari on iOS, this doesn't work.

The reason why it doesn't work on safari iOS is because it considers mouse events(on desktop) different than the touch events(on iOS)

If I present this in a UIWebView or WKWebView, can I make the WebView act more like desktop Safari, so that I can drag the elements around?

.. I'm just curious if this is possible with WebView

Yes it is possible in WebView. You can use the Jquery UI for drag and drop with an additional library that translates mouse events into touch which is what you need. Have a look at jquery-ui-touch-punch . With this your drag and drop from Jquery UI would work on iOS or any device. You may use something like:

function touchHandler(event) {
    var touch = event.changedTouches[0];

    var simulatedEvent = document.createEvent("MouseEvent");
        simulatedEvent.initMouseEvent({
        touchstart: "mousedown",
        touchmove: "mousemove",
        touchend: "mouseup"
    }[event.type], true, true, window, 1,
        touch.screenX, touch.screenY,
        touch.clientX, touch.clientY, false,
        false, false, false, 0, null);

    touch.target.dispatchEvent(simulatedEvent);
    event.preventDefault();
}

function init() {
    document.addEventListener("touchstart", touchHandler, true);
    document.addEventListener("touchmove", touchHandler, true);
    document.addEventListener("touchend", touchHandler, true);
    document.addEventListener("touchcancel", touchHandler, true);
}

to convert mouse events into touch and it works like magic. Have a look at this tutorial on jQuery UI Touch Punch, with jQuery UI . Here's a cool article with demo on the same.

code courtesy

Answer 2

Well, it is possible with a WebView. The actual answer is : how ? How, in order to get a great UX result. Mobile device is not a desktop, the actual solution is a matter of UX, dedicated to mobile:

You could use a longtap to make a card "flying/ready-for-drag" (turning scroll off). Or Use a zone/flat-button on the card, that users hook to drag it. Thoughts. You should absolutely avoid scroll & drag 'turned on' at the same time. It's drag OR scroll, never drag AND scroll.

EDIT You can use :

• JQuery UI to manage dragging @ https://jqueryui.com/draggable/

• JQuery Mobile vmouse events. (works well with mousemove , the best). @ https://api.jquerymobile.com/category/events/

Answer 3

In case you are just wondering if there is a simple way to enable drag&drop cross-platform even on mobile, I may suggest you to use Interact.js , a nice UI interaction library I've used successfully in multiple projects.

Using a little code you can achieve a working drag&drop, like this:

var position = { x: 0, y: 0 };
interact('.element')
  .draggable({
    onmove: function(e) {
      var target = e.target;

      // calculate position
      position.x += e.dx;
      position.y += e.dy;

      // translate the element
      target.style.webkitTransform = 'translate(' + position.x + 'px, ' + position.y + 'px)';  
    }    
  });

You can find this working example I've just built here: http://codepen.io/leonardfactory/pen/MwPBjZ

I've tested it on mobile safari, and it works just fine, allowing drag&drop. You can find further documentation on its doc page .

I hope this answers your question, if your needs are more specific, feel free to comment and I'll try to edit my answer to adapt it.

Answer 4

I'm not sure if this is what you need, but take a look at this jquery-ui-touch-punch .

It handles the touchevents (touchstart, touchmove, touchend) in order to work properly.

Take a look at the demopage, where you can try it out on your mobile device touchpunch demo page .