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

!--index.wxml--!--图片宽大于屏幕宽--image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagefirstsrc}}" bindload="imageLoad"/image!--图片高大于屏幕高--!--image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagesecondsrc}}" bindload="imageLoad"/image--!--图片宽高大于屏幕宽高--!--image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagethirdsrc}}" bindload="imageLoad"/image--

//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

//util.jsfunction 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}