js 图片的等比例缩放判断

Posted 2023-05-12

// javascript Document

var flag=false;
function DrawImage(ImgD)
var image=new Image();
image.src=ImgD.src;
if(image.width>0 && image.height>0)
flag=true;
if(image.width<=570 && ImgD.width>1)
if(image.width/image.height>= 570/600)
if(image.width>570)
ImgD.width=570;
ImgD.height=(image.height*600)/image.width;
else
ImgD.width=image.width;
ImgD.height=image.height;

/*ImgD.alt="bigpic" */

else
if(image.height>600)
ImgD.height=600;
ImgD.width=(image.width*570)/image.height;
else
ImgD.width=image.width;
ImgD.height=image.height;

/*ImgD.alt="bigpic" */




这样写不执行，有谁给改改？
if(image.width<=570 && ImgD.width>1)

这是考虑当宽小于570时，图片的大小不变。

参考技术A 这个有很大的兼容问题
用ietester 和 火狐 都测一下
应该会有一款能用本回答被提问者采纳

Js图片等比例缩放

    
<img src="chargein_cashgift_detail.png" class="img" >

function showImg(img,maxW,maxH) {
    let objImg = new Image();
    let w,h,wRatio,hRatio;
    let Ratio =1; //比率
    objImg.src=img.src;
    if(img.naturalWidth){
        w =img.naturalWidth;
        h =img.naturalHeight;
    }else{
        w =objImg.width;
        h =objImg.height;
    }
    wRatio = maxW / w;
    hRatio = maxH / h;
    if(maxW === 0 && maxH ===0){
        Ratio = 1;
    }else if(maxW === 0){
        if(hRatio<1) {
            Ratio = hRatio;
        }
    }else if (maxH === 0){
        if(wRatio<1){
            Ratio = wRatio;
        }
    }else if (wRatio<1 || hRatio<1){
        Ratio = (wRatio<=hRatio?wRatio:hRatio);
    }
    if (Ratio<1){
        w = w * Ratio;
        h = h * Ratio;
    }
    img.width =w;
    img.height =h;
    console.log(w)
    console.log(h)
}
let img1 =document.querySelectorAll(‘img‘)[0]
showImg(img1,300,200)

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