小程序实现分销海报
1、简介：
用户生成属于自己的海报，其他人扫码此图片上的二维码，进入相应的小程序页面，同时带上相关的参数 parent_id 从而绑定上下级关系；
注意：一下是微信小程序的实现方法；支付宝基本同样，只有稍微小的部分修改，例如：支付宝小程序不需要调起授权保存相册，会在你使用的时候自动调用
2、例如海报：
3、分销海报包含了：
1、海报背景（可选择更换）；
2、个人二维码；
3、用户个人信息；姓名、头像等
4、海报长按保存功能；
4、实现原理：
海报图、以及个人二维码(扫码可跳转小程序固定一个页面)由后台接口返回两张图片；前台使用canvas将此海报绘制出来；
5、html代码
微信小程序方法
<canvas class="mycanvas" canvas-id="myCanvas" :style="{height: canvasHeight + \'px\',width: canvasWidth+ \'px\'}"
@longtap="getAuthAndSaveImg"> </canvas>
支付宝小程序方法
<canvas id="canvas" :style="{height: canvasHeight + \'px\',width: canvasWidth+ \'px\'}" class="canvas" @longtap="getAuthAndSaveImg" />
6、js代码：
注意：canvas将图片绘制，必须将网络图片下载到本地，或者使用本地图片也是可以的
export default { data() { return { cardData:\'\', avatarImg: \'\', // 用户头像 avatarContent: \'\', // 文字 codeUrl: \'\', // 二维码图片 canvasWidth: 0, // 画布大小 canvasHeight: 0, codeTestPicBg: \'\' // 背景图 } }, onLoad() { this.loadImg(); }, methods: { // 生成确定画布大小 loadImg(){ let that = this; // 获取系统信息 支付宝小程序这里只需要将 wx. 改为 my. wx.getSystemInfo({ success: function (res) { that.canvasWidth = res.windowWidth * 1; that.canvasHeight = res.windowHeight * 1; that.getAvatarImgurl(); } }); }, // 获取用户信息 getAvatarImgurl(){ let that = this; uni.getStorage({ key: \'scopeUserInfo\', success: function (res) { that.avatarImg = res.data.avatarUrl; that.avatarContent = \'您的好友\' + res.data.nickName + \'为您分享！\' that.downloadAvar(); } }); }, // 下载用户头像 支妇保小程序同样也需要先下载 downloadAvar(){ let that = this;
// 支付包小程序 同样wx 改为 my ；返回值 tempFilePath 改为 apFilePath wx.downloadFile({ url: that.avatarImg, success: function (res) { that.avatarImg = res.tempFilePath wx.hideLoading(); that.getTempFile(); }, fail: function (err) { wx.showToast({ title: "下载头像败,稍后重试！", icon: "none", duration: 5000 }); } }); }, // 获取CODE吗 getTempFile: function () { let that = this; request.post(that.websiteUrl + \'/api/v4/drp/create/applet/code\',{ goods_id: 0, scene: \'\' + 0 + \'&\' + this.drpdata.shop_info.user_id, shop_id: this.drpdata.shop_info.id }).then(res=>{ //继续生成商品的小程序码 that.downloadCodepic(res.data.url); }) }, // 下载code码 downloadCodepic(url){ let that = this; wx.downloadFile({ url: \'https://\' + url, success: function (res) { that.codeUrl = res.tempFilePath wx.hideLoading(); that.downloadBgCard(); }, fail: function (err) { wx.showToast({ title: "下载二维码失败,稍后重试！", icon: "none", duration: 5000 }); } }); }, // 下载背景图 downloadBgCard(){ let that = this; wx.downloadFile({ url: \'https://feiquanshijie-oss.oss-cn-hangzhou.aliyuncs.com/data/attached/qrcode/themes/20130815061226_k3jWZ.png?v=1582584928\', success: function (res) { console.log(res) that.codeTestPicBg = res.tempFilePath wx.hideLoading(); //生成数据 that.setCanvas(); }, fail: function (err) { wx.showToast({ title: "下载背景图失败,稍后重试！", icon: "none", duration: 5000 }); } }); }, // 绘制画布 微信小程序 setCanvas() { let that = this; let ctx = wx.createCanvasContext("myCanvas"); ctx.rect( 0, 0, that.canvasWidth, that.canvasHeight ); ctx.setFillStyle("#fff"); ctx.fill(); // 背景图片 ctx.drawImage( \'../../../static/card_bg.png\', 0, 0, that.canvasWidth, that.canvasHeight ); // 用户图片 ctx.drawImage( that.avatarImg, 30, 40, 50, 50 ); that.drawFont(ctx, that.avatarContent, 100, 70,0,0,0,17,14,\'#000\'); that.drawFont(ctx, \'长按保存图片\', 140, 25,0,0,0,17,14,\'#333\'); // code图片 ctx.drawImage( // that.codeUrl, \'../../../static/123860applet.png\', that.canvasWidth/3, that.canvasWidth/3, that.canvasWidth/3, that.canvasWidth/3 ); ctx.globalCompositeOperation = "source-over"; ctx.draw(); //绘制到canvas },
// 长安图片 getAuthAndSaveImg(){ let _this = this; wx.getSetting({ success(res) { if (res.authSetting[\'scope.writePhotosAlbum\']) { _this.saveShareImg(); } else if (res.authSetting[\'scope.writePhotosAlbum\'] === undefined) { wx.authorize({ scope: \'scope.writePhotosAlbum\', success() { _this.saveShareImg(); }, fail(){ wx.showToast({ title: \'您没有授权，无法保存到相册\', icon: \'none\', duration: 2000 }) } }) }else { uni.openSetting({ success(res) { if (res.authSetting[\'scope.writePhotosAlbum\']) { _this.saveShareImg(); }else{ wx.showToast({ title:\'您没有授权，无法保存到相册\', icon:\'none\', duration: 2000 }) } } }) } } }) }, //点击保存到相册 saveShareImg: function () { var that = this; wx.showLoading({ title: \'正在保存\', mask: true, }) setTimeout(function () { wx.canvasToTempFilePath({ canvasId: \'myCanvas\', fileType: \'jpg\', success: function (res) { wx.hideLoading(); var tempFilePath = res.tempFilePath; wx.saveImageToPhotosAlbum({ filePath: tempFilePath, success(res) { wx.showModal({ content: \'图片已保存到相册，赶紧晒一下吧~\', showCancel: false, confirmText: \'好的\', confirmColor: \'#333\', success: function (res) { }, fail: function (res) { wx.showToast({ title: \'系统繁忙，请稍后重新尝试！\', icon: \'none\', duration: 2000 }) } }) }, fail: function (res) { wx.showToast({ title: res.errMsg, icon: \'none\', duration: 2000 }) } }) } }); }, 1000); }, // 设置文字大小，并填充颜色。 drawFont: function (ctx, contentTitle, x, y, x1, y1,x2,y2,fontSize,color) { let that = this; let str = contentTitle; let firstline; ctx.setFontSize(fontSize); ctx.setFillStyle(color); ctx.fillText(firstline, x + x1, y + y1); }, }, }
支付宝小程序绘制 以及 长安下载；支付宝小程序不需要去判断授权 直接下载就行 会自动调用授权
draw() { const ctx = my.createCanvasContext(\'canvas\') ctx.drawImage(this.codeTestPicBg, 0, 0, this.canvasWidth, this.canvasHeight); ctx.drawImage(this.avatarImg, 30, 40, 50, 50); var numH = 1.234*(this.canvasWidth/2); ctx.drawImage(this.codeUrl, this.canvasWidth/4, this.canvasWidth/3, this.canvasWidth/2,numH); ctx.setFontSize(16) ctx.fillText(\'长按保存图片\', 140, 20); ctx.fillText(this.avatarContent, 100, 70); ctx.globalCompositeOperation = "source-over"; ctx.draw() }, // 长安图片 点击保存到相册 getAuthAndSaveImg(){ var that = this; my.showLoading({ title: \'正在保存\', mask: true, }) setTimeout(function () { const ctx = my.createCanvasContext(\'canvas\'); ctx.toTempFilePath({ fileType: \'jpg\', success: function (res) { my.hideLoading(); var tempFilePath = res.apFilePath; my.saveImage({ url: tempFilePath, showActionSheet: true, success(res) { my.alert({ title: \'温馨提示\', content: \'图片已保存到相册，赶紧晒一下吧~\', buttonText: \'我知道了\', success: function (res) { }, fail: function (res) { my.showToast({ title: \'系统繁忙，请稍后重新尝试！\', icon: \'none\' }) } }) }, fail: function (res) { my.showToast({ title: res.errMsg, icon: \'none\' }) } }) } }); }, 1000); },
7、上下级关系处理：
例如扫码后跳转商城首页，那么在首页的onload 事件中，拿到 e ，便能拿到相应的传递的参数，例如：parent_id
onLoad(e) { if(e.parent_id){ this.user_id = e.parent_id; uni.setStorageSync(\'isplatformUserID\', this.user_id); } },
8、canvas两个图片重叠时显示的方法——globalCompositeOperation
