javascript html 鼠标放大镜效果

1、鼠标放大镜效果

鼠标放大镜效果，将鼠标移入到左图片，则可以在其右边看到放大的图片，且鼠标移动滑块的大小即为右图显示图片。实际效果如下图所示：

<!DOCTYPE html>

<html>

<head>

#little_image {

width: 400px;

height: 400px;

position: absolute;

top: 0px;

left: 0px;

}

#image {

display: block;

width: 400px;

height: 400px;

position: absolute;

}

#big_image {

width: 500px;

height: 500px;

border: 1px solid grey;

overflow: hidden;

display: none;

position: absolute;

top: 0px;

left: 400px;

}

#images {

display: block;

width: 1000px;

height: 1000px;

position: absolute;

}

#slider_block {

width: 200px;

height: 200px;

position: absolute;

border: 1px solid lightgrey;

cursor: all-scroll;

display: none;

}

</style>

</head>

<body>

</div>

</div>

</body>

var littleImage = document.getElementById('little_image');

var bigImage = document.getElementById('big_image');

var sliderBlock = document.getElementById('slider_block');

//为littleImage添加鼠标移入事件

littleImage.onmousemove = function(event) {

event = event || window.event;

sliderBlock.style.display = "block"; //移入鼠标显示sliderBlock

bigImage.style.display = "inline-block"; //移入鼠标显示bigImage

// 1、限定sliderBlock的活动范围

var disX = event.clientX - sliderBlock.offsetWidth / 2; //鼠标点击位置－移动块宽度的1/2

var disY = event.clientY - sliderBlock.offsetHeight / 2;

//最大移动位置就是little_image的宽度－移动块的宽度

var distenceMaxX = littleImage.offsetWidth - sliderBlock.offsetWidth;

var distenceMaxY = littleImage.offsetHeight - sliderBlock.offsetHeight;

if (disX < 0) {

disX = 0;

} else if (disX >= distenceMaxX) {

disX = distenceMaxX

}

if (disY < 0) {

disY = 0;

} else if (disY >= distenceMaxY) {

disY = distenceMaxY;

}

// 2、通过改变sliderBlock的left和top的指来让sliderBlock随着鼠标移动

sliderBlock.style.left = disX + "px";

sliderBlock.style.top = disY + "px";

// 3、通过计算sliderblock在littleImage的比例，计算bigImage在大图中显示的比例

var scaleX = disX / distenceMaxX;

var scaleY = disY / distenceMaxY;

var images = document.getElementById('images');

bigImage.scrollLeft = (images.offsetWidth - bigImage.offsetWidth) * scaleX;

bigImage.scrollTop = (images.offsetHeight - bigImage.offsetHeight) * scaleY;

}

//添加鼠标移出事件

littleImage.onmouseleave = function() {

sliderBlock.style.display = 'none'; // sliderBlock隐藏

bigImage.style.display = 'none'; // bigImage隐藏

}

</script>

</html>

附：offset ｜ client ｜ scroll 关系图

巴特西

javascript html 鼠标放大镜效果

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