收藏
回答

wx.canvasGetImageData 在真机上读取的数据失真,怎么解决?

调用相机拍照后,将相片保存到本地;再打开照片读取照片的像素值,在真机上失真,请问怎么解决???急............

注:在保存照片前,特意将第1、2、3个像素分别设置为红、绿、蓝,保存的照片也显示像素值设置成功了,在真机上读取时,第1、2、3个像素值明显错误,在开发环境下读取正确。机器是华为mate20。

以下为核心代码:

//第一步:照相;

   //第二步:将照片的第1个像素设置为红色,透明值230;第2个像素设置为绿色,透明值240;第3个像素设置为蓝色,透明值250;以示标记

   //第三步:将照片保存到本地相册

this.ctx.takePhoto({

      quality: 'high',

      success: (res) => {

        var context = wx.createCanvasContext('myCanvas');

        var cvsInfoWidth = 400; //照片宽400

        var cvsInfoHeight = 500; //照片高500

        context.drawImage(res.tempImagePath, 0, 0, cvsInfoWidth, cvsInfoHeight);

        context.draw(true, res => { 

          wx.canvasGetImageData({

            canvasId: 'myCanvas',

            x:0,

            y:0,

            width: cvsInfoWidth,

            height: cvsInfoHeight,

            success(res) {

              const data1 = res.data; //获取图片像素值

              data1[0] =255; //红色

              data1[1] = 0;

              data1[2] = 0;

              data1[3] =230; //png照片的透明值

              data1[4] = 0;

              data1[5] =255; //绿色

              data1[6] = 0;

              data1[7] = 240; //png照片的透明值

              data1[8] = 0;

              data1[9] = 0;

              data1[10] = 250; //蓝色

              data1[11] = 255; //png照片的透明值

              //重新设置canvas data

              wx.canvasPutImageData({

                canvasId: 'myCanvas',

                x:0,

                y:0,

                width: Math.ceil(cvsInfoWidth),

                height: Math.ceil(cvsInfoHeight),

                data: data1,

                success(res) {

                }

              });

            }

          })

        });           

        //---------使用wx.canvasToTempFilePath将画布保存为图片---------

        setTimeout(() => {

          wx.canvasToTempFilePath({

            canvasId: 'myCanvas',

            fileType:'png',

            quality:1,

            success: function (res) {

              //将照片保存到本地相册

            },

            fail: function (res) {}

          });

        }, 1000);

      }       

    });


//在另外一个页面读取照片的像素值

  wx.chooseImage({

      count: 1,

      sizeType: ['original'],

      sourceType: ['album'],

      success(res) {

        var cvsInfoWidth = 400;

        var cvsInfoHeight = 500;

        var context = wx.createCanvasContext('myCanvas1');

        context.drawImage(res.tempFilePaths[0], 0, 0, cvsInfoWidth, cvsInfoHeight, 0, 0, cvsInfoWidth, cvsInfoHeight);

        context.draw(true, res => {

          //获取canvas图片数据       

          wx.canvasGetImageData({

            canvasId: 'myCanvas1',

            x:0,

            y:0,

            width:  cvsInfoWidth,

            height: cvsInfoHeight,

            success(res) {

              console.log(res.data);

            }

          })           

        });

      }

    })

最后一次编辑于  01-11
回答关注问题邀请回答
收藏

3 个回答

登录 后发表内容
问题标签