New Twiddle

components.my-zoom.js

import Ember from 'ember';

let previousMouseX = 0;
let previousMouseY = 0;
let mouseXInImage = 0;
let mouseYInImage = 0;
let scale = 1;
const zoomSpeed = 0.1;

export default Ember.Component.extend({
  didInsertElement() {
    this._super(...arguments);
    console.log('didInsertElement');
    $('.zoomable-area').on('wheel', (event) => {
      this.pinch(event);
    });
  },

  pinch(event) {
    console.time('test');
    const $zoomableArea = this.$('.zoomable-area');
    const $image = this.$('.image');
    console.timeEnd('test')
    const wheelDeltaY = event.originalEvent.deltaY;
    
    // Get mouse position relative to the wrapper.
    const mouseX = event.pageX - $zoomableArea.offset().left;
    const mouseY = event.pageY - $zoomableArea.offset().top;
    
    console.log(`mouseX: ${mouseX}, mouseY: ${mouseY}`);
    
    // Find current location on the image at the current scale.
    mouseXInImage = mouseXInImage + ((mouseX - previousMouseX) / scale);
    mouseYInImage = mouseYInImage + ((mouseY - previousMouseY) / scale);
    
    // Update the scale.
    scale += wheelDeltaY * zoomSpeed;
    scale = scale < 1 ? 1 : (scale > 64 ? 64 : scale);
    
    // Determine the location in the wrapper at the new scale and relative to
    // the cursor location in the image.
    const imageX = (mouseX - mouseXInImage) / scale;
    const imageY = (mouseY - mouseYInImage) / scale;

    // Save the current mouse location location relative to the wrapper.
    previousMouseX = mouseX;
    previousMouseY = mouseY;
    
    const transform = `scale(${scale}) translate(${imageX}px, ${imageY}px)`;
    console.log(`transform: ${transform}`);
    $image.css('transform', transform);

    const transformOrigin = `${mouseXInImage}px ${mouseYInImage}px`;
    console.log(`transformOrigin: ${transformOrigin}`);
    $image.css('transform-origin', transformOrigin);
  },
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

styles.app.css

*, *:before, *:after {
  box-sizing: border-box;
}

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

.zoomable-area {
 	border: dashed 1px;
  width: 300px;
  height: 300px;
  overflow: hidden;
}

.image {
  user-drag: none; 
  user-select: none;
  -moz-user-select: none;
  -webkit-user-drag: none;
  -webkit-user-select: none;
  -ms-user-select: none;
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
{{my-zoom}}

templates.components.my-zoom.hbs

<h1>My Zoom</h1>
<div class="zoomable-area">
	<img class="image" src="http://placekitten.com/g/298/298" />
</div>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}