微信小程序开发-canves 图片压缩获取base64

淡淡的烟草味﹌ 2022-12-17 08:39 172阅读 0赞

makeCanvas: function(imgPath) {
          console.log("start draw");
          var ctx = wx.createCanvasContext('canvas')
          // 设置背景
          ctx.setFillStyle('#ffffff')
          ctx.fillRect(0, 0, this.data.canvasWidth, this.data.canvasWidth)
    
    
    
          // 描绘图片
          /**
           * @function drawImage Canvas描绘图片
           * @param {String} imgPath 图片路径
           * @param {Number} imgWidth 图片宽度
           * @param {Number} imgHeight 图片高度
           * @author mossbaoo
           */
           let cWidth = this.data.canvasWidth*0.5;
            let cHeight = this.data.canvasWidth*0.5;
            let imgWidth = this.data.imgInfo.width;
            let imgHeight = this.data.imgInfo.height
            console.log(cWidth+"_"+cHeight+"_"+imgWidth+"_"+imgHeight);
            let dWidth = cWidth/imgWidth;  // canvas与图片的宽度比例
            let dHeight = cHeight/imgHeight;  // canvas与图片的高度比例
            if (imgWidth > cWidth && imgHeight > cHeight || imgWidth < cWidth && imgHeight < cHeight) {
              if (dWidth > dHeight) {
                ctx.drawImage(imgPath, 0, (imgHeight - cHeight/dWidth)/2, imgWidth, cHeight/dWidth, 0, 0, cWidth, cHeight)
              } else {
                ctx.drawImage(imgPath, (imgWidth - cWidth/dHeight)/2, 0, cWidth/dHeight, imgHeight, 0, 0, cWidth, cHeight)
              }
            } else {
              if (imgWidth < cWidth) {
                ctx.drawImage(imgPath, 0, (imgHeight - cHeight/dWidth)/2, imgWidth, cHeight/dWidth, 0, 0, cWidth, cHeight)
              } else {
                ctx.drawImage(imgPath, (imgWidth - cWidth/dHeight)/2, 0, cWidth/dHeight, imgHeight, 0, 0, cWidth, cHeight)
              }
            }
    
    
          ctx.draw();
          console.log("end draw");
          debugger;
          var that = this;
          wx.canvasToTempFilePath({
                canvasId: 'canvas',
                success: function success(res) {
                  that.setData({
                    canvasImgUrl: res.tempFilePath
                  });
                  that.canvasShow=false;
                  console.log(res.tempFilePath);
                  // 人脸验证
                  let base64 = wx.getFileSystemManager().readFileSync(res.tempFilePath, 'base64');
    
                  console.log("base64two:"+base64.length);
                  if (!that.isLoading) {
                      that.setData({
                          isLoading: !0
                      });
                      //先活体face/faceVerify
                      that.vertifyImg(base64);
                  }
    
                },
                complete: function complete(e) {
                }
              });
        }