【轉】微信小程序開發之圖片等比例縮放 獲取屏幕尺寸圖片尺寸 自適應

原文【https://blog.csdn.net/qq_31383345/article/details/53127804】

早上在論壇上看到有人寫了關於圖片等比例縮放的文章,只是判斷了圖片寬是否大於屏幕寬.我之前在做Android的時候也會遇到圖片等比例縮放的問題.應該是用圖片寬高比和屏幕寬高比做判斷.做個筆記.

老規矩,先上圖.

1.圖片高寬比小於屏幕高寬比

 

2.圖片高寬比大於屏幕高寬比

 

3.這種其實也是圖片高寬比小於屏幕高寬比,但是高寬都大於屏幕高寬.所以不能簡單用高寬來判斷,應該是用高寬比判斷后做縮放.

 

上代碼:

1.index.wxml

 

<!--index.wxml-->
<!--圖片寬大於屏幕寬-->
<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagefirstsrc}}" bindload="imageLoad"></image>
<!--圖片高大於屏幕高-->
<!--<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagesecondsrc}}" bindload="imageLoad"></image>-->
<!--圖片寬高大於屏幕寬高-->
<!--<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagethirdsrc}}" bindload="imageLoad"></image>-->

<!--index.wxml-->
<!--圖片寬大於屏幕寬-->
<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagefirstsrc}}" bindload="imageLoad"></image>
<!--圖片高大於屏幕高-->
<!--<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagesecondsrc}}" bindload="imageLoad"></image>-->
<!--圖片寬高大於屏幕寬高-->
<!--<image style="width: {{imagewidth}}px; height: {{imageheight}}px;"  src="{{imagethirdsrc}}" bindload="imageLoad"></image>-->

2.index.js

 

//index.js
//獲取應用實例
var imageUtil = require('../../utils/util.js');
var app = getApp()
Page({
  data: {
    imagefirstsrc: 'http://bpic.588ku.com/back_pic/00/03/85/1656205138bbe2d.png',//圖片鏈接
    imagesecondsrc: 'http://bpic.588ku.com/back_pic/04/07/63/28581203949ca9d.jpg!/fw/400/quality/90/unsharp/true/compress/true',//圖片鏈接
    imagethirdsrc:'http://img1.gtimg.com/ent/pics/hv1/13/71/2061/134034643.jpg',
    imagewidth: 0,//縮放后的寬
    imageheight: 0,//縮放后的高

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

//index.js
//獲取應用實例
var imageUtil = require('../../utils/util.js');
var app = getApp()
Page({
  data: {
    imagefirstsrc: 'http://bpic.588ku.com/back_pic/00/03/85/1656205138bbe2d.png',//圖片鏈接
    imagesecondsrc: 'http://bpic.588ku.com/back_pic/04/07/63/28581203949ca9d.jpg!/fw/400/quality/90/unsharp/true/compress/true',//圖片鏈接
    imagethirdsrc:'http://img1.gtimg.com/ent/pics/hv1/13/71/2061/134034643.jpg',
    imagewidth: 0,//縮放后的寬
    imageheight: 0,//縮放后的高

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

3.util.js

 

//util.js
function imageUtil(e) {
  var imageSize = {};
  var originalWidth = e.detail.width;//圖片原始寬
  var originalHeight = e.detail.height;//圖片原始高
  var originalScale = originalHeight/originalWidth;//圖片高寬比
  console.log('originalWidth: ' + originalWidth)
  console.log('originalHeight: ' + originalHeight)
  //獲取屏幕寬高
  wx.getSystemInfo({
    success: function (res) {
      var windowWidth = res.windowWidth;
      var windowHeight = res.windowHeight;
      var windowscale = windowHeight/windowWidth;//屏幕高寬比
      console.log('windowWidth: ' + windowWidth)
      console.log('windowHeight: ' + windowHeight)
      if(originalScale < windowscale){//圖片高寬比小於屏幕高寬比
        //圖片縮放后的寬為屏幕寬
         imageSize.imageWidth = windowWidth;
         imageSize.imageHeight = (windowWidth * originalHeight) / originalWidth;
      }else{//圖片高寬比大於屏幕高寬比
        //圖片縮放后的高為屏幕高
         imageSize.imageHeight = windowHeight;
         imageSize.imageWidth = (windowHeight * originalWidth) / originalHeight;
      }

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

module.exports = {
  imageUtil: imageUtil
}

//util.js
function imageUtil(e) {
  var imageSize = {};
  var originalWidth = e.detail.width;//圖片原始寬
  var originalHeight = e.detail.height;//圖片原始高
  var originalScale = originalHeight/originalWidth;//圖片高寬比
  console.log('originalWidth: ' + originalWidth)
  console.log('originalHeight: ' + originalHeight)
  //獲取屏幕寬高
  wx.getSystemInfo({
    success: function (res) {
      var windowWidth = res.windowWidth;
      var windowHeight = res.windowHeight;
      var windowscale = windowHeight/windowWidth;//屏幕高寬比
      console.log('windowWidth: ' + windowWidth)
      console.log('windowHeight: ' + windowHeight)
      if(originalScale < windowscale){//圖片高寬比小於屏幕高寬比
        //圖片縮放后的寬為屏幕寬
         imageSize.imageWidth = windowWidth;
         imageSize.imageHeight = (windowWidth * originalHeight) / originalWidth;
      }else{//圖片高寬比大於屏幕高寬比
        //圖片縮放后的高為屏幕高
         imageSize.imageHeight = windowHeight;
         imageSize.imageWidth = (windowHeight * originalWidth) / originalHeight;
      }
     
    }
  })
  console.log('縮放后的寬: ' + imageSize.imageWidth)
  console.log('縮放后的高: ' + imageSize.imageHeight)
  return imageSize;
}

module.exports = {
  imageUtil: imageUtil
}