howto 在线编辑器 | howto代码测试

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>* {box-sizing: border-box;}

.img-magnifier-container {
  position:relative;
}

.img-magnifier-glass {
  position: absolute;
  border: 3px solid #000;
  border-radius: 50%;
  cursor: none;
  /*设置放大镜的大小：*/
  width: 100px;
  height: 100px;
}
</style>
<script>
function magnify(imgID, zoom) {
  var img, glass, w, h, bw;
  img = document.getElementById(imgID);
  /* 创建放大镜：*/
  glass = document.createElement("DIV");
  glass.setAttribute("class", "img-magnifier-glass");
  /*插入放大镜:*/
  img.parentElement.insertBefore(glass, img);
  /* 设置放大镜的背景属性：*/
  glass.style.backgroundImage = "url('" + img.src + "')";
  glass.style.backgroundRepeat = "no-repeat";
  glass.style.backgroundSize = (img.width * zoom) + "px " + (img.height * zoom) + "px";
  bw = 3;
  w = glass.offsetWidth / 2;
  h = glass.offsetHeight / 2;
  /*当有人在图像上移动放大镜时执行一个函数：*/
  glass.addEventListener("mousemove", moveMagnifier);
  img.addEventListener("mousemove", moveMagnifier);
  /* 也适用于触摸屏：*/
  glass.addEventListener("touchmove", moveMagnifier);
  img.addEventListener("touchmove", moveMagnifier);
  function moveMagnifier(e) {
    var pos, x, y;
    /*防止在图像上移动时可能发生的任何其他操作*/
    e.preventDefault();
    /*获取光标的x和y位置：*/
    pos = getCursorPos(e);
    x = pos.x;
    y = pos.y;
    /* 防止放大镜位于图像之外：*/
    if (x > img.width - (w / zoom)) {x = img.width - (w / zoom);}
    if (x < w / zoom) {x = w / zoom;}
    if (y > img.height - (h / zoom)) {y = img.height - (h / zoom);}
    if (y < h / zoom) {y = h / zoom;}
    /*设置放大镜的位置：*/
    glass.style.left = (x - w) + "px";
    glass.style.top = (y - h) + "px";
    /*显示放大镜“看到”的内容：*/
    glass.style.backgroundPosition = "-" + ((x * zoom) - w + bw) + "px -" + ((y * zoom) - h + bw) + "px";
  }
  function getCursorPos(e) {
    var a, x = 0, y = 0;
    e = e || window.event;
    /*获取图像的x和y位置：*/
    a = img.getBoundingClientRect();
    /*计算光标相对于图像的 x 和 y 坐标：*/
    x = e.pageX - a.left;
    y = e.pageY - a.top;
    /*考虑任何页面滚动：*/
    x = x - window.pageXOffset;
    y = y - window.pageYOffset;
    return {x : x, y : y};
  }
}
</script>
</head>
<body>

<h1>图像放大镜</h1>

<p>鼠标悬停在图片上：</p>

<p>启动放大功能时，您可以随意更改放大镜的强度。</p>

</body>
</html>

报个问题: