#### 复现路径 安卓版本的长图加载不出来，在ios上正常

需求：使用canvas-2d绘制用户头像昵称，小程序码生成相应图片海报 异常：某些ios机型绘制保存后的图片为空白图片 手机型号：iphone8；系统版本：ios11.3 ；微信：7.0.15 手机型号：iPhone11 Pro Max；系统版本：13.2.3 手机型号：iPhoneX max  ; ios:13.6 ;微信版本：7.0.15 api使用：wx.downloadFile;wx.canvasToTempFilePath;wx.saveImageToPhotosAlbum wxml <canvas style="position: absolute;top:0;left:100%;width: 750px;height: 1206px;" canvas-id='canvas'></canvas> 方法封装 const scopeName = { "userInfo": "用户信息", "userLocation": "地理位置", "address": "通讯地址", "invoiceTitle": "发票抬头", "invoice": "发票", "werun": "微信运动步数", "record": "录音功能", "writePhotosAlbum": "保存到相册", "camera": "摄像头" }; const authorize = (scope) => { return new Promise((resolve, reject) => { const failText = `须授权${scopeName[scope]}！`; wx.getSetting({ success(res) { if (res.authSetting[`scope.${scope}`]) { resolve(true); } else { wx.authorize({ scope: `scope.${scope}`, success() { resolve(true); }, fail() { wx.showModal({ title: "提示", content: `检测到未打开${scopeName[scope]}权限`, confirmText: "授权", success(res) { if (res.confirm) { wx.openSetting({ success(res) { if (res.authSetting[`scope.${scope}`]) { resolve(true); } else { reject(failText); } } }); } else { reject(failText); } }, fail() { reject(failText) } }); }, }); } }, fail() { reject(failText); } }); }); }; const saveImageToPhotosAlbum = (filePath) => { return new Promise((resolve, reject) => { wx.saveImageToPhotosAlbum({ filePath, success(res) { resolve(res); }, fail() { reject(); }, }); }); }; const saveImage = (url, type = 'online') => { return new Promise(async (resolve, reject) => { const isAuth = await await authorize("writePhotosAlbum").catch(err => { reject(err); }); if (isAuth) { let tempFilePath = url; if (type === 'online') { tempFilePath = await downloadFile(url).catch(err => { reject('图片下载失败') }); } const val = await saveImageToPhotosAlbum(tempFilePath).catch(err => { reject('取消保存'); }) if (val) { resolve(true); } else { reject(); } } else { reject('无授权'); } }) }; /**canvas保存图片 */ const canvasToTempFilePath = (params, component) => { return new Promise((resolve, reject) => { wx.canvasToTempFilePath({ ...params, success(res) { resolve(res); }, fail(res) { reject(); }, }, component) }); } 逻辑 /**获取海报 */ createPoster(bg, qrcode, avatar, nickName) { return new Promise(async (resolve, reject) => { if (!bg || !qrcode || !avatar) return reject('图片资源异常'); const ctx = wx.createCanvasContext("canvas", this); //获取画布 //画海报 ctx.drawImage(bg, 0, 0, 750, 1206); //画小程序码 ctx.drawImage(qrcode, 466, 937, 202, 202); //画昵称 ctx.font = '22px PingFangSC-Regular' ctx.setFillStyle('#6C3511'); ctx.fillText(nickName, 198, 1000); //画头像 const avatarInfo = { space: 78, x: 98, y: 971 } ctx.save(); ctx.beginPath(); ctx.arc(avatarInfo.x + avatarInfo.space / 2, avatarInfo.y + avatarInfo.space / 2, avatarInfo.space / 2, 0, Math.PI * 2, false); ctx.clip(); ctx.drawImage(avatar, avatarInfo.x, avatarInfo.y, avatarInfo.space, avatarInfo.space); ctx.restore(); ctx.draw(); const dpr = wx.getSystemInfoSync().pixelRatio || 1; setTimeout(async () => { const res = await canvasToTempFilePath({ x: 0, y: 0, width: 750 * dpr, height: 1026 * dpr, destWidth: 750 * dpr, destHeight: 1206 * dpr, canvasId: "canvas", fileType: "jpg", }, this); if (res && res.tempFilePath) { resolve(res.tempFilePath); } else { reject('画板异常'); } }, 200) }); }, async onShareImage() { wx.showLoading({ title: '正在生成图片', mask: true }); try { let bgData = "/assets/images/share/background.jpg"; const nickName="昵称"; const qrcodeUrl="";//二维码网络地址（已加入白名单） const avatar="";//用户头像网络地址（已加入白名单） const text = nickName.length > 10 ? `${nickName.substring(0,9)}...` : nickName; const avatarData = await downloadFile(avatar); //头像  const qrcodeData = await downloadFile(qrcodeUrl); //小程序码数据  const posterData = await this.createPoster(bgData, qrcodeData, avatarData, text); //生成海报数据 const result = await saveImage(posterData, "file"); //保存图片 if (result) { wx.hideLoading(); wx.showToast({ title: "图片已保存", mask: true }); } } catch (error) { wx.hideLoading(); wx.showToast({ icon: "none", title: `分享图片生成失败！${error}`, mask: true }); } },

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