javascript - 鼠标点缩放图片-滚轮事件

Question

这是缩放工作示例。我希望图像在图像上的实际鼠标位置上放大。如何做到这一点？没有图书馆。

const image = document.querySelector('img');
const zoom = {
    min: 1,
    max: 3,
    value: 1,
    step: 0.1
};

image.addEventListener('wheel', event => {
   event.preventDefault();

   if (event.deltaY < 0) {
     zoom.value = zoom.value >= zoom.max ? zoom.max : zoom.value + zoom.step;
     
     } else  if (event.deltaY > 0) {
      zoom.value = zoom.value <= zoom.min ? zoom.min : zoom.value - zoom.step;
   }
  
  image.style.transform = `scale(${zoom.value})`
	}
)

div {
  width: 500px;
  overflow: hidden;
}

img {
  width: 100%;
}

<div>
  <img src="https://picjumbo.com/wp-content/uploads/free-stock-photos-san-francisco-1080x720.jpg">
</div>

egzample

Answer 1

const image = document.querySelector('img');
const zoom = {
    min: 1,
    max: 3,
    value: 1,
    step: 0.1
};

var div = document.querySelector('div');

div.addEventListener('wheel', event => {
   event.preventDefault();

   if (event.deltaY < 0) {
     zoom.value = zoom.value >= zoom.max ? zoom.max : zoom.value + zoom.step;
     
     } else  if (event.deltaY > 0) {
      zoom.value = zoom.value <= zoom.min ? zoom.min : zoom.value - zoom.step;
   }
  
  image.style.transform = `scale(${zoom.value})`
  var xPerc = (x * 100) / image.width;
  var yPerc = (y * 100) / image.height;
    image.style.transformOrigin = xPerc + '%' + ' ' + yPerc + '%';
    }
)

var x, y;

div.addEventListener('mousemove', e => {
    x = e.clientX - div.offsetLeft;
  y = e.clientY - div.offsetTop;
})

div {
  width: 500px;
  overflow: hidden;
}

img {
  width: 100%;
}

<div>
  <img src="https://picsum.photos/200">
</div>

试了一下您的示例，发现 transform-origin 可能会成功。添加了相对于图像容器的坐标 x,y，并将它们转换为百分比，以便设置图像的 tranform-origin 样式属性。