Html 移动 Safari（iPad、iPod、iPhone）中的原生 HTML5 拖放？

Native HTML5 Drag and Drop in Mobile Safari (iPad, iPod, iPhone)?

提问by Gabriel

I've successfully implemented native HTML5 Drag and Dropfor moving HTML elements inside a page(just, say, a div from one place to another, nothing related to interacting with the host OS' files whatsoever). This works fine in Chrome and Safari on a PC but I can't start a drag operation in my iPad's Safari.

我已经成功地实现了原生 HTML5 拖放，用于在页面内移动 HTML 元素（只是，从一个地方到另一个地方的 div，与与主机操作系统的文件交互无关）。这在 PC 上的 Chrome 和 Safari 中运行良好，但我无法在 iPad 的 Safari 中开始拖动操作。

I've found this so far:

到目前为止，我发现了这一点：

Using Drag and Drop From JavaScript

Safari, Dashboard, and WebKit-based applications include support for customizing the behavior of drag and drop operations within your HTML pages.

Note: This technology is supported only on desktop versions of Safari. For iPhone OS, use DOM Touch, described in Handling Events (part of Safari Web Content Guide) and Safari DOM Additions Reference.

使用 JavaScript 拖放

Safari、仪表板和基于 WebKit 的应用程序支持自定义 HTML 页面中的拖放操作行为。

注意：此技术仅在桌面版 Safari 上受支持。对于 iPhone 操作系统，请使用 DOM Touch，如处理事件（Safari Web 内容指南的一部分）和 Safari DOM 添加参考中所述。

Here. But it's outdated (2009-06-08).

在这里。但它已经过时了（2009-06-08）。

Doe's anyone know if it is possible to use nativeHTML5 in Mobile Safari? (I don't want javascript-framework like solutions like jQuery UI).

有谁知道是否可以在 Mobile Safari 中使用原生HTML5？（我不想要像 jQuery UI 这样的解决方案的 javascript 框架）。

Thanks!

谢谢！

回答by Mike Bethany

I found this incredibly useful javascript code that adds the iOS event shims for you:

我发现了这个非常有用的 javascript 代码，它为你添加了 iOS 事件垫片：

https://github.com/timruffles/ios-html5-drag-drop-shim

https://github.com/timruffles/ios-html5-drag-drop-shim

Complete code just in case the code is deleted sometime in the future (it happens too often):

完整的代码，以防将来某个时候代码被删除（这种情况经常发生）：

(function(doc) {

  log = noop; // noOp, remove this line to enable debugging

  var coordinateSystemForElementFromPoint;

  function main(config) {
    config = config || {};

    coordinateSystemForElementFromPoint = navigator.userAgent.match(/OS 5(?:_\d+)+ like Mac/) ? "client" : "page";

    var div = doc.createElement('div');
    var dragDiv = 'draggable' in div;
    var evts = 'ondragstart' in div && 'ondrop' in div;

    var needsPatch = !(dragDiv || evts) || /iPad|iPhone|iPod/.test(navigator.userAgent);
    log((needsPatch ? "" : "not ") + "patching html5 drag drop");

    if(!needsPatch) return;

    if(!config.enableEnterLeave) {
      DragDrop.prototype.synthesizeEnterLeave = noop;
    }

    doc.addEventListener("touchstart", touchstart);
  }

  function DragDrop(event, el) {

    this.touchPositions = {};
    this.dragData = {};
    this.el = el || event.target

    event.preventDefault();

    log("dragstart");

    this.dispatchDragStart()
    this.elTranslation = readTransform(this.el);

    this.listen()

  }

  DragDrop.prototype = {
    listen: function() {
      var move = onEvt(doc, "touchmove", this.move, this);
      var end = onEvt(doc, "touchend", ontouchend, this);
      var cancel = onEvt(doc, "touchcancel", cleanup, this);

      function ontouchend(event) {
        this.dragend(event, event.target);
        cleanup();
      }
      function cleanup() {
        log("cleanup");
        this.touchPositions = {};
        this.el = this.dragData = null;
        return [move, end, cancel].forEach(function(handler) {
          return handler.off();
        });
      }
    },
    move: function(event) {
      var deltas = { x: [], y: [] };

      [].forEach.call(event.changedTouches,function(touch, index) {
        var lastPosition = this.touchPositions[index];
        if (lastPosition) {
          deltas.x.push(touch.pageX - lastPosition.x);
          deltas.y.push(touch.pageY - lastPosition.y);
        } else {
          this.touchPositions[index] = lastPosition = {};
        }
        lastPosition.x = touch.pageX;
        lastPosition.y = touch.pageY;
      }.bind(this))

      this.elTranslation.x += average(deltas.x);
      this.elTranslation.y += average(deltas.y);
      this.el.style["z-index"] = "999999";
      this.el.style["pointer-events"] = "none";
      writeTransform(this.el, this.elTranslation.x, this.elTranslation.y);

      this.synthesizeEnterLeave(event);
    },
    synthesizeEnterLeave: function(event) {
      var target = elementFromTouchEvent(this.el,event)
      if (target != this.lastEnter) {
        if (this.lastEnter) {
          this.dispatchLeave();
        }
        this.lastEnter = target;
        this.dispatchEnter();
      }
    },
    dragend: function(event) {

      // we'll dispatch drop if there's a target, then dragEnd. If drop isn't fired
      // or isn't cancelled, we'll snap back
      // drop comes first http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#drag-and-drop-processing-model
      log("dragend");

      if (this.lastEnter) {
        this.dispatchLeave();
      }

      var target = elementFromTouchEvent(this.el,event)

      if (target) {
        log("found drop target " + target.tagName);
        this.dispatchDrop(target)
      } else {
        log("no drop target, scheduling snapBack")
        once(doc, "dragend", this.snapBack, this);
      }

      var dragendEvt = doc.createEvent("Event");
      dragendEvt.initEvent("dragend", true, true);
      this.el.dispatchEvent(dragendEvt);
    },
    dispatchDrop: function(target) {
      var snapBack = true;

      var dropEvt = doc.createEvent("Event");
      dropEvt.initEvent("drop", true, true);
      dropEvt.dataTransfer = {
        getData: function(type) {
          return this.dragData[type];
        }.bind(this)
      };
      dropEvt.preventDefault = function() {
         // https://www.w3.org/Bugs/Public/show_bug.cgi?id=14638 - if we don't cancel it, we'll snap back
        this.el.style["z-index"] = "";
        this.el.style["pointer-events"] = "auto";
        snapBack = false;
        writeTransform(this.el, 0, 0);
      }.bind(this);

      once(doc, "drop", function() {
        log("drop event not canceled");
        if (snapBack) this.snapBack()
      },this);

      target.dispatchEvent(dropEvt);
    },
    dispatchEnter: function() {

      var enterEvt = doc.createEvent("Event");
      enterEvt.initEvent("dragenter", true, true);
      enterEvt.dataTransfer = {
        getData: function(type) {
          return this.dragData[type];
        }.bind(this)
      };

      this.lastEnter.dispatchEvent(enterEvt);
    },
    dispatchLeave: function() {

      var leaveEvt = doc.createEvent("Event");
      leaveEvt.initEvent("dragleave", true, true);
      leaveEvt.dataTransfer = {
        getData: function(type) {
          return this.dragData[type];
        }.bind(this)
      };

      this.lastEnter.dispatchEvent(leaveEvt);
      this.lastEnter = null;
    },
    snapBack: function() {
      once(this.el, "webkitTransitionEnd", function() {
        this.el.style["pointer-events"] = "auto";
        this.el.style["z-index"] = "";
        this.el.style["-webkit-transition"] = "none";
      },this);
      setTimeout(function() {
        this.el.style["-webkit-transition"] = "all 0.2s";
        writeTransform(this.el, 0, 0)
      }.bind(this));
    },
    dispatchDragStart: function() {
      var evt = doc.createEvent("Event");
      evt.initEvent("dragstart", true, true);
      evt.dataTransfer = {
        setData: function(type, val) {
          this.dragData[type] = val;
          return val;
        }.bind(this),
        dropEffect: "move"
      };
      this.el.dispatchEvent(evt);
    }
  }

  // event listeners
  function touchstart(evt) {
    var el = evt.target;
    do {
      if (el.hasAttribute("draggable")) {
        evt.preventDefault();
        new DragDrop(evt,el);
      }
    } while((el = el.parentNode) && el !== doc.body)
  }

  // DOM helpers
  function elementFromTouchEvent(el,event) {
    var touch = event.changedTouches[0];
    var target = doc.elementFromPoint(
      touch[coordinateSystemForElementFromPoint + "X"],
      touch[coordinateSystemForElementFromPoint + "Y"]
    );
    return target
  }

  function readTransform(el) {
    var transform = el.style["-webkit-transform"];
    var x = 0
    var y = 0
    var match = /translate\(\s*(\d+)[^,]*,\D*(\d+)/.exec(transform)
    if(match) {
      x = parseInt(match[1],10)
      y = parseInt(match[2],10)
    }
    return { x: x, y: y };
  }

  function writeTransform(el, x, y) {
    var transform = el.style["-webkit-transform"].replace(/translate\(\D*\d+[^,]*,\D*\d+[^,]*\)\s*/g, '');
    el.style["-webkit-transform"] = transform + " translate(" + x + "px," + y + "px)";
  }

  function onEvt(el, event, handler, context) {
    if(context) handler = handler.bind(context)
    el.addEventListener(event, handler);
    return {
      off: function() {
        return el.removeEventListener(event, handler);
      }
    };
  }

  function once(el, event, handler, context) {
    if(context) handler = handler.bind(context)
    function listener(evt) {
      handler(evt);
      return el.removeEventListener(event,listener);
    }
    return el.addEventListener(event,listener);
  }


  // general helpers
  function log(msg) {
    console.log(msg);
  }

  function average(arr) {
    if (arr.length === 0) return 0;
    return arr.reduce((function(s, v) {
      return v + s;
    }), 0) / arr.length;
  }

  function noop() {}

  main(window.iosDragDropShim);


})(document);

回答by alex

Touch events do work now on Safari too (including Mobile). This article has nice code snippets that you can start from:

触摸事件现在也适用于 Safari（包括 Mobile）。这篇文章有很好的代码片段，你可以从：

http://www.html5rocks.com/en/mobile/touch/

http://www.html5rocks.com/en/mobile/touch/