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wx.canvasToTempFilePath报错

发布于 8 年前作者 liguo11263 次浏览最后编辑 8 年前来自 ask

<canvas style=“height:{{canvasSize.height}}px;width:{{canvasSize.width}}px” canvas-id=‘share-pyq’ binderror=‘canvasIdErrorCallback’></canvas>

（canvas直接在page下）

drawShareCanvas(){

var that = this

…//canvas绘制

this.setData({

      canvasSize: { height: size.height, width: size.width, opacity: 0 }

    })

    ctx.draw(true,that.saveCanvasToFile)

    console.log()

  },

  saveCanvasToFile() {

    var that = this

    wx.canvasToTempFilePath({

      canvasId: ‘share-pyq’,

      success: function (res) {

…//成功后的操作

      },

      fail(res){

        console.log(res)

      }

    }, that)

}

控制台报错：“canvasToTempFilePath:fail:illegal arguments”

2 回复
qinmin
qinmin1 楼6 年前

wx.canvasToTempFilePath的第二个参数this指代的是绘图所用的context对象，不是当前page

lei14
lei142 楼6 年前

完美解决方案，

在绘图过程中可能会设置canvas的宽高（this.setData()这是异步的）

setTimeout(function () {

    ctx.draw(false, function () {

    wx.showLoading({

        title: ‘努力生成中…’

    })

    wx.canvasToTempFilePath({

        x: 0,

        y: 0,

        canvasId: ‘longImgCanvas’,

        success: res => {

            console.log(res.tempFilePath);

            wx.previewImage({

            current: res.tempFilePath,

                urls: [res.tempFilePath]

            });

            wx.hideLoading();

            that.setData({

                isShowLongImgCanvas: false

            });

        },

        fail: function (res) {

            console.log(res)

        }

        })

    });

}, 500);