我将一个元素作为字符串绘制到画布上。然后我希望能够单击该元素（或点击移动设备）并将其拖动。我现在拥有的是：
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="bootstrap.min.css" />
<link type="text/css" rel="stylesheet" href="stylesheet.css"/>
<script src="jquery-1.11.0.js"></script>
</head>
<body>
<canvas id="canvas1" width="662" height="983">
<script src="jquery-1.11.0.js"></script>
</canvas>
<script>
var chosenChord=""; //this gets updated at various times by excluded code, but that code works, because the chord does always print correctly below
` $("button").click(function() {
canvas = document.getElementById('canvas1');
canvas1.addEventListener('click', on_canvas_click, false);
function on_canvas_click(ev) {
x = ev.clientX - canvas1.offsetLeft-40;
y = ev.clientY - canvas1.offsetTop;
//add to canvas
var canvas = document.getElementById("canvas1");
var context = …