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step 1:下载源代码

直接通过 git 下载 wxa-plugin-canvas 源代码。

https://github.com/jasondu/wxa-plugin-canvas

step 2:将miniprogram_dist目录拷贝到自己的项目组件目录中

miniprogram\components\miniprogram_dist

step 3:页面引入该组件:

miniprogram/pages/my/UserPosterQrCodeService/index.json

{
  "usingComponents": {
    "poster": "/components/miniprogram_dist/poster/index"
  }
}

step 4:在 wxml 中使用组件

miniprogram/pages/my/UserPosterQrCodeService/index.wxml

<poster id="poster" config="{{posterConfig}}" bind:success="onPosterSuccess" bind:fail="onPosterFail">
    <button>点击生成海报</button>
</poster>

step 5:添加配置信息posterConfig

来源:https://github.com/jasondu/wxa-plugin-canvas/blob/a54cc04f4c638cbef33ecdf40de425afe68e1aa0/pages/index/index.js

(1)图片的域名添加到downloadFile合法域名中(开发设置-服务器域名-downloadFile合法域名)

    登陆微信公众平台https://mp.weixin.qq.com,输入小程序的登陆邮件和密码,需用管理员微信扫码完成登陆,否则会提示“没有配置权限”。

    选择开发-》开发设置-》开始配置,配置https域名

(2)在data中添加配置信息posterConfig

miniprogram/pages/my/UserPosterQrCodeService/index.js

 data: {
    url: '',
    winWidth: 0,
    winHeight: 0,
    oneHeight: 0, // 风景图的高度
    ewmWidth: 0, //二维码的高度

    oneWidth: 0, //左右两边的空白
    twoWidth: 0, //二维码和边框之间的距离
    fontHeight: 0,
    text1: '',
    text2: '',
    text3: '',
    text4: '',

    posterConfig: {
      width: 750,
      height: 1000,
      backgroundColor: '#fff',
      debug: false,
      blocks: [
        {
          x: 0,
          y: 10,
          width: 750, // 如果内部有文字,由文字宽度和内边距决定
          height: 120,
          paddingLeft: 0,
          paddingRight: 0,
          borderWidth: 10,
          borderColor: 'red',
          backgroundColor: 'blue',
          borderRadius: 40,
          text: {
            text: [
              {
                text: '金额¥ 1.00',
                fontSize: 80,
                color: 'yellow',
                opacity: 1,
                marginLeft: 50,
                marginRight: 10,
              },
              {
                text: '金额¥ 1.00',
                fontSize: 20,
                color: 'yellow',
                opacity: 1,
                marginLeft: 10,
                textDecoration: 'line-through',
              },
            ],
            baseLine: 'middle',
          },
        }
      ],
      texts: [
        {
          x: 0,
          y: 180,
          text: [
            {
              text: '长标题长标题长标题长标题长标题长标题长标题长标题长标题',
              fontSize: 40,
              color: 'red',
              opacity: 1,
              marginLeft: 0,
              marginRight: 10,
              width: 200,
              lineHeight: 40,
              lineNum: 2,
            },
            {
              text: '原价¥ 1.00',
              fontSize: 40,
              color: 'blue',
              opacity: 1,
              marginLeft: 10,
              textDecoration: 'line-through',
            },
          ],
          baseLine: 'middle',
        },
        {
          x: 10,
          y: 330,
          text: '金额¥ 1.00',
          fontSize: 80,
          color: 'blue',
          opacity: 1,
          baseLine: 'middle',
          textDecoration: 'line-through',
        },
      ],
      images: [
        {
          url: 'http://weixin.usdotnet.com/imgage/bgk_wanjiale.jpg',
          width: 300,
          height: 300,
          y: 450,
          x: 0,
          // borderRadius: 150,
          // borderWidth: 10,
          // borderColor: 'red',
        },
        {
          url: 'http://weixin.usdotnet.com/imgage/bgk_wanjiale.jpg',
          width: 100,
          height: 100,
          y: 450,
          x: 400,
          borderRadius: 100,
          borderWidth: 10,
        },
      ],
      lines: [
        {
          startY: 800,
          startX: 10,
          endX: 300,
          endY: 800,
          width: 5,
          color: 'red',
        }
      ]

    }

  },

 

step 6:添加生成事件处理函数

 onPosterSuccess(e) {
        const { detail } = e;
        wx.previewImage({
            current: detail,
            urls: [detail]
        })
    },
    onPosterFail(err) {
        console.error(err);
    }

 

异步生成海报步骤

(1)在 wxml 中

<button bindtap="onCreatePoster">异步生成海报</button>

(2)在js中

/**
 * 异步生成海报
 */
import Poster from '../../../components/miniprogram_dist/poster/poster';
 /**
   * 异步生成海报
   */
  onCreatePoster() {
    Poster.create();
  },

组件原理说明文章

https://juejin.im/post/5b7e48566fb9a01a1059543f

使用案例

https://github.com/CavinCao/mini-blog