2018-07-13 小程序网络图片的压缩问题

源码：http://115.28.152.1:3000/zhouyan/picture.git

图片压缩 1网络图片需要调用downloadFile 获取在本地的路径--》drawCanvas

  2本地图片 直接调用 drawCanvas

// 图片压缩

  pictap: function () {

    var that = this;

    var url ='https://mdapi.zjwist.com/mediainfo3/get/67587';

    wx.downloadFile({

      url: url,

      success: function (sres) {

        console.log(sres);

        url = sres.tempFilePath;

        that.drawCanvas(url);

      }, fail: function (fres) {

      }

    })

  },

  //利用Canvas 缩放图片

  drawCanvas: function (url) {

    var that = this;

    var ctx = wx.createCanvasContext('attendCanvasId');

    ctx.drawImage(url, 0, 0, 100, 100);

    ctx.draw(true, function () {

      that.prodImageOpt(url);    });//在回调进行保存不会出现空白

  },

  // 生成图片

  prodImageOpt: function (url) {

    console.log(url);

    var that = this;

    wx.canvasToTempFilePath({

      canvasId: 'attendCanvasId',

      success: function success(res) {

        var path = res.tempFilePath;

        console.log(path);

      that.setData({

          canvasImgUrl: path

        });

      wx.setStorageSync("path", path);

      }

    });

  }

.xml 文件代码

<canvas style=" width: 100px;

  height: 100px;

" canvas-id="attendCanvasId"/>