app端 uni.canvasToTempFilePath不执行，小程序可以正常执行

不清楚你的逻辑 但是你可以试试下面这段代码(app端正常导出) 对比一下找出你的bug

<template>  
    <view class="test-canvas">  
        <canvas style="width: 300px; height: 200px;" canvas-id="myCanvas" ></canvas>  
        <button @tap="getCanvasToTempFilePath">导出</button>  
    </view>  
</template>  
<script>  
    export default {  
        methods: {  
            getCanvasToTempFilePath() {  
                uni.canvasToTempFilePath({  
                    x: 100,  
                    y: 200,  
                    width: 50,  
                    height: 50,  
                    destWidth: 100,  
                    destHeight: 100,  
                    canvasId: 'myCanvas',  
                    success: (res) => {  
                        console.log(res.tempFilePath,"res--------------");  
                    },  
                    fail: (err) => {  
                        console.log('fail', err);  
                    },  
                    complete: () => {  
                        console.log('complete');  
                    }  
                });  
            }  
        },  
        mounted() {  

        }  
    }  
</script>

检查代码有没有问题

//组件内
<canvas :class="className" :canvas-id="canvasId" :width="higtCanvasSize" :height="higtCanvasSize" :style="{
width: higtCanvasSize + 'px',
height: higtCanvasSize + 'px'
}" />
//props接收
canvasId: {
type: String,
default: 'almostLottery'
},

const ctx = uni.createCanvasContext(canvasId, this)

// 保存绘图并导出图片
ctx.draw(true, (() => {
let drawTimer = setTimeout(() => {
clearTimeout(drawTimer)
drawTimer = null
console.log(this.canvasId)
// #ifndef MP-ALIPAY
uni.canvasToTempFilePath({ //不执行```javascript

                            canvasId: this.canvasId,  
                            destWidth: this.higtCanvasSize,  
                            destHeight: this.higtCanvasSize,  
                            success: (res) => {  
                                // 在 H5 平台下，tempFilePath 为 base64  
                                console.log(res.tempFilePath)  
                                this.handlePrizeImg({  
                                    ok: true,  
                                    data: res.tempFilePath,  
                                    msg: '画布导出生成图片成功'  
                                })  
                            },  
                            fail: (err) => {  
                                this.handlePrizeImg({  
                                    ok: false,  
                                    data: err,  
                                    msg: '画布导出生成图片失败'  
                                })  
                            }  
                        }, this)  
                        // #endif  
                    }, 500)  
                })())

https://ask.dcloud.net.cn/question/192496 确实有这个问题