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1 <!doctype html>
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2 <html>
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3 <head>
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4 <meta name="viewport" content="width=device-width, initial-scale=1">
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5 <style>
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6 @import "/site.css";
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7
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8 div[drag] {
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9 border: 1px solid;
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10 margin: 8px;
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11 padding: 8px;
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12 touch-action: none;
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13 background-color: LightGreen;
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14 }
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15 </style>
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16 <script src="https://cdn.jsdelivr.net/npm/interactjs/dist/interact.js"></script>
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17 <script>
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18 'use strict';
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19
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20 let dxDrag, dyDrag;
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21
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22 function dragStartListener(event) {
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23 dxDrag = 0;
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24 dyDrag = 0;
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25 }
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26
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27 function dragMoveListener(event) {
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28 dxDrag += event.dx;
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29 dyDrag += event.dy;
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30 event.target.style.transform = `translate(${dxDrag}px, ${dyDrag}px)`;
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31 }
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32
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33 function dragEndListener(event) {
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34 event.target.style.transform = null;
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35 }
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36
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37 function indexOf(a,el) {
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38 for( let i=0; i<a.length; i++ ) {
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39 if( a[i] === el )
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40 return i;
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41 }
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42 return -1;
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43 }
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44
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45 function dragEnterListener(event) {
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46 console.log(event);
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47 let entered = event.target;
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48 let dragging = event.relatedTarget;
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49 if( entered === dragging )
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50 return;
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51 let divs = document.querySelectorAll('div[drag]');
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52 let iEntered = indexOf(divs,entered);
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53 let iDragging = indexOf(divs,dragging);
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54 console.log(iDragging+' '+iEntered);
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55 let parent = entered.parentNode;
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56 if( iDragging < iEntered ) {
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57 let next = divs[iEntered+1];
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58 if( next ) {
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59 parent.insertBefore( dragging, next );
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60 } else {
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61 parent.appendChild( dragging );
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62 }
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63 } else {
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64 parent.insertBefore( dragging, entered );
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65 }
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66 }
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67
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68 function init() {
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69 let dad = interact('div[drag]');
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70 dad.draggable({
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71 listeners: {
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72 start: dragStartListener,
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73 move: dragMoveListener,
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74 end: dragEndListener,
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75 }
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76 });
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77 dad.dropzone({
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78 ondragenter: dragEnterListener,
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79 });
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80 }
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81 </script>
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82 </head>
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83 <body>
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84 <h1><a href="https://interactjs.io/">interact.js</a></h1>
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85
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86 <p>This has a number of problems. First, it is clearly too complicated. And this means that it isn't on just one JavaScript file. One has to use the modern horror of <b>npm</b> to get it (which I refuse to do). The suggested way of handling dragging doesn't work when the DOM changes, as the example below shows. There is probably some complicated way around this, but I can't be bothered given the other issues.</p>
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87
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88 <div>
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89 <script>
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90 for( let i=1; i<=10; i++ ) {
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91 document.write(`
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92 <div drag id="${i}">${i} - drag me</div>
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93 ` );
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94 }
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95 </script>
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96 </div>
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97 </body>
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98 <script> init(); </script>
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99 </html>
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