前端时间公司要求在小程序中生成分享图片，于是就有了下面的例子，话不多说，直接代码贴上：
//index.js
//获取应用实例
const app = getApp()
//tips:需要在小程序后台配置downloadFile合法域名
Page({
data: {
widWidth: 0,
widHeight: 0,
screenWid:0,
multiple:0
},
launchAppError: function (e) {
console.log(e.detail.errMsg)
},
onLoad: function () {
let ctxId = wx.createCanvasContext('shareCanvas')
let screenWid = wx.getSystemInfoSync().windowWidth;
this.setData({
multiple: 750 / screenWid
})
this.setData({
widWidth: 750 / this.data.multiple,
widHeight: 1334 / this.data.multiple
})
let that = this;
wx.getImageInfo({
src: 'https://oacademo-1252397592.file.myqcloud.com/miniprogram/images/bg.jpg',
success: function (res) {
console.log(res.path);
ctxId.drawImage(res.path, 0, 0, 750 / that.data.multiple, 1354 / that.data.multiple);
that.getIcon(ctxId, that, screenWid);
}
})
},
/**
* 明星头像
*/
getIcon(ctxId, that,screenWid){
/*明星头像*/
wx.getImageInfo({
src: 'https://www.baidu.com/img/baidu_jgylogo3.gif',
success: function (res) {
console.log(res.path);
ctxId.save();
ctxId.beginPath(); //开始绘制
var avatarurl_width = 180 / that.data.multiple; //绘制的头像宽度
var avatarurl_heigth = 180 / that.data.multiple; //绘制的头像高度
var avatarurl_x = 285 / that.data.multiple; //绘制的头像在画布上的位置
var avatarurl_y = 18 / that.data.multiple; //绘制的头像在画布上的位置
ctxId.arc(avatarurl_width / 2 + avatarurl_x, avatarurl_heigth / 2 + avatarurl_y, avatarurl_width / 2, 0, Math.PI * 2, false);
ctxId.clip();//画好了圆 剪切 原始画布中剪切任意形状和尺寸。一旦剪切了某个区域，则所有之后的绘图都会被限制在被剪切的区域内 这也是我们要save上下文的原因
ctxId.drawImage(res.path, avatarurl_x, avatarurl_y, avatarurl_width, avatarurl_heigth)
ctxId.restore(); //恢复之前保存的绘图上下文 恢复之前保存的绘图上下午即状态 还可以继续绘制
that.getFont(ctxId, that, screenWid);
}
})
},
/**
* 明星标题
*/
getFont(ctxId,that, screenWid){
ctxId.setTextAlign('center') // 文字居中
ctxId.setFillStyle('#f74565') // 文字颜色：黑色
ctxId.setFontSize(parseInt(34 / that.data.multiple)) // 文字字号：22px
ctxId.fillText("实时排行： 1000+", screenWid / 2, 347 / that.data.multiple)
ctxId.stroke()
ctxId.draw();
},
savetup: function () {
wx.canvasToTempFilePath({
x: 0,
y: 0,
width: this.data.widWidth,
height: this.data.widHeight,
destWidth: 750,
destHeight: 1354,
canvasId: 'shareCanvas',
success: function (res) {
//调取小程序当中获取图片
console.log(res.tempFilePath);
wx.saveImageToPhotosAlbum({
filePath: res.tempFilePath,
success(res) {
wx.showModal({
title: '存图成功',
content: '图片成功保存到相册了，去发圈噻~',
showCancel: false,
confirmText: '好哒',
confirmColor: '#72B9C3',
success: function (res) {
if (res.confirm) {
console.log('用户点击确定');
}
}
})
}
})
},
fail: function (res) {
console.log(res)
}
})
}
})
<view class="container">
<canvas canvas-id="shareCanvas" style="width:{{widWidth}}px;height:{{widHeight}}px"></canvas>
<button bindtap='savetup' class="save">保存图片</button>
</view>
