New Twiddle

a-handle.component.js

import Ember from 'ember';

export default Ember.Component.extend({
	attributeBindings: ["draggable"],
  classNames: ["a-handle"],
  draggable: true,
  
  setupDragImg: Ember.on("didInsertElement", function() {
    this._dragImg = document.createElement("img");
    this._dragImg.src = "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==";
    
    document.body.appendChild(this._dragImg);

  }),
  
  removeDragImg: Ember.on("willDestroyElement", function() {
    document.body.removeChild(this._dragImg);
  }),
  
  mouseDown(e) {
    e.preventDefault();
    this.set("dragging", true);
    
    //e.dataTransfer.setDragImage(this._dragImg, 0, 0);
   Ember.$(document).on("mousemove.a-handle", this.mouseMovee.bind(this));
    Ember.$(document).one("mouseup", this.mouseUpp.bind(this));
    
    this.set("origX", e.originalEvent.clientX);
    this.set("origWidth", parseInt(this.$().closest("th,td").css("width").replace(/px$/, ""), 10));
  },
  
  mouseMovee(e) {
    if (this.get("dragging")) {
      const newX = e.originalEvent.pageX;
      console.log(newX);
      if (newX > 0) {
        this.sendAction("resize",
            this.get("origWidth") - this.get("origX") + newX);
      }
    }
  },
  
  mouseUpp(e) {
    this.set("dragging", false);
    this.set("origX", false);
    Ember.$(document).off("mousemove.a-handle");
  }
});

a-handle.template.hbs

  

application.controller.js

import Ember from 'ember';

const {
  computed
} = Ember;

export default Ember.Controller.extend({
  actions: {
    resize(column, width) {
      if (width > 10) {
        const fullWidth = this.get("fullWidth");

        if (column === "a") {
          let newBWidth = fullWidth - this.get("cWidthPx") - width;
          if (newBWidth > 10) {
            console.log("set a width");
            this.set("aWidthPx", width);
            this.set("bWidthPx", newBWidth);
          }
        } else {
          console.log("b column");
          let newCWidth = fullWidth - this.get("aWidthPx") - width;
          if (newCWidth > 10) {
            this.set("bWidthPx", width);
            this.set("cWidthPx", newCWidth);
          }
        }
      }
    }
  },
  
  aWidthPx: 150,
  
  aWidth: computed("aWidthPx", function() {
    return `width: ${this.get("aWidthPx")}px`;
  }),
  
  bWidthPx: 150,
  
  bWidth: computed("bWidthPx", function() {
    return `width: ${this.get("bWidthPx")}px`;
  }),
  
  cWidthPx: 150,
  
  cWidth: computed("cWidthPx", function() {
    return `width: ${this.get("cWidthPx")}px`;
  }),
  
  fullWidth: 450,
  
 	fullWidthStyle: computed("fullWidth", function() {
    return `width: ${this.get("fullWidth")}px`;
  }),
  
  appName: 'Ember Twiddle'
  
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
<table style={{fullWidthStyle}}>
  <tr>
    <th style={{aWidth}}>a really long title{{a-handle resize=(action "resize" "a")}}</th>
    <th style={{bWidth}}>b{{a-handle tagName="i" resize=(action "resize" "b")}}</th>
    <th style={{cWidth}}>c</th>
  </tr>
  <tr>
  	<td>A</td>
    <td>B</td>
    <td>C</td>
  </tr>
</table>
{{outlet}}
<br>
<br>

styles.app.css

* {
  box-sizing: border-box;
}
[draggable] {
  -khtml-user-drag: element;
  -webkit-user-drag: element;
}

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.a-handle {
  position: absolute;
  right: 0;
  top: 0;
  display:block;
  width: 5px;
  height: 100%;
  background: transparent;
  float: right;
  cursor: ew-resize;
  visibility: invisible;
}

table {
  border-collapse: collapse;
  table-layout: fixed;
}

table, td, th, tr {
  padding: 0;
  margin: 0;
}

td, th {
  position: relative;
  border: 1px solid black;
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis
}

twiddle.json

{
  "version": "0.6.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}