缩小图像以适合div [英] Scale down image to fit div

问题描述

我正在尝试按比例缩小一个装料，以适合一个大于最大宽度和高度设置的div容器.我下面的代码获取图像的宽度和高度以及允许的最大尺寸设置.

I am trying to scale down an inage to fit a div container that are greater then the max width and heights set. I have the code below that gets the width and height of the image and the sets max sizes allowed.

这是我无法进入的深度，它在下面加载的图像为662x599.宽度大于允许的最大值，因此我需要将其正确缩小并放置在div的中心.

This is were I'm out of my depth, the image it loads below is 662x599. The width is greater the the max allowed so I need it to scale down correctly and be placed into the center of the div.

var max_width = 713;
var max_height = 550;

var img = new Image();
img.onload = function() {
    img.width = this.width;
    img.height = this.height;
}
img.src = 'files.jpg';

下面是我手动调整图像大小的示例，它看起来不错，可以为您提供一个粗略的外观示例.我打算使用样式"top"和"left"将图像放置在div的中心.

Below is an example me resizing the image manually that looks good to give you a rough example of how it should look should. I intent to use styles "top" and "left" to place the image in the center of the div.

<img style="width: 613px; height: 550px; top: 0px; left: 50px;" src="files.jpg">

任何帮助都将非常感谢.

Any help would be great thanks.

推荐答案

这是用于计算width，height，top，left的代码.

This is code to calculate width, height, top, left.

// max_width  = 713
// max_height = 550
// img.width  = 662
// img.height = 599

scale_width = max_width / img.width;
scale_height = max_height / img.height;

scale = Math.min(scale_width, scale_height);

width = img.width * scale;  // 608
height = img.height * scale;  // 550

left = (max_width - width)/2; // 52
top = (max_height - height)/2;  // 0

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