微信小程序 图片等比例缩放图片自适应屏幕

微信小程序 图片等比例缩放

早上在论坛上看到有人写了关于图片等比例缩放的文章,只是判断了图片宽是否大于屏幕宽.我之前在做Android的时候也会遇到图片等比例缩放的问题.应该是用图片宽高比和屏幕宽高比做判断.做个笔记.

老规矩,先上图.

1.图片高宽比小于屏幕高宽比

2.图片高宽比大于屏幕高宽比

3.这种其实也是图片高宽比小于屏幕高宽比,但是高宽都大于屏幕高宽.所以不能简单用高宽来判断,应该是用高宽比判断后做缩放.

上代码:

1.index.wxml

rush:xml;"> irstsrc}}" bindload="imageLoad">

2.index.js

rush:js;">

//index.js
//获取应用实例
var imageUtil = require('../../utils/util.js');
var app = getApp()
Page({
data: {
imagefirstsrc: 'http://bpic.588ku.com/back_pic/00/03/85/1656205138bbe2d.png',//图片链接
imagesecondsrc: 'http://bpic.588ku.com/back_pic/04/07/63/28581203949ca9d.jpg!/fw/400/quality/90/unsharp/true/compress/true',//图片链接
imagethirdsrc:'http://img1.gtimg.com/ent/pics/hv1/13/71/2061/134034643.jpg',imagewidth: 0,//缩放后的宽
imageheight: 0,//缩放后的高

},onLoad: function () {
},imageLoad: function (e) {
var imageSize = imageUtil.imageUtil(e)
this.setData({
imagewidth: imageSize.imageWidth,imageheight: imageSize.imageHeight
})
}
})

3.util.js

rush:js;"> //util.js function imageUtil(e) { var imageSize = {}; var originalWidth = e.detail.width;//图片原始宽 var originalHeight = e.detail.height;//图片原始高 var originalScale = originalHeight/originalWidth;//图片高宽比 console.log('originalWidth: ' + originalWidth) console.log('originalHeight: ' + originalHeight) //获取屏幕宽高 wx.getSystemInfo({ success: function (res) { var windowWidth = res.windowWidth; var windowHeight = res.windowHeight; var windowscale = windowHeight/windowWidth;//屏幕高宽比 console.log('windowWidth: ' + windowWidth) console.log('windowHeight: ' + windowHeight) if(originalScale < windowscale){//图片高宽比小于屏幕高宽比 //图片缩放后的宽为屏幕宽 imageSize.imageWidth = windowWidth; imageSize.imageHeight = (windowWidth * originalHeight) / originalWidth; }else{//图片高宽比大于屏幕高宽比 //图片缩放后的高为屏幕高 imageSize.imageHeight = windowHeight; imageSize.imageWidth = (windowHeight * originalWidth) / originalHeight; }

}
})
console.log('缩放后的宽: ' + imageSize.imageWidth)
console.log('缩放后的高: ' + imageSize.imageHeight)
return imageSize;
}

module.exports = {
imageUtil: imageUtil
}