微信小程序开发之图片等比例缩放 获取屏幕尺寸图片尺寸 自适应

wxml：

<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagefirstsrc}}" bindload="imageLoad"></image>

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

})

}

})

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
}