uniapp echarts 适配H5与微信小程序

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前言

接上文：uniapp 微信小程序使用echarts，这篇文章目的为使用uniapp时提供一个同时兼容H5和小程序的echarts组件，在使用时尽量减少心智负担。

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一、修改 ec-canvas组件

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首先修改uniapp 微信小程序使用echarts中的ec-canvas组件，将initChart方法置于该组件内部，而不是存在于业务组件中。

1.1 在ec-canvas组件methods中定义一个initChart方法

export default {
	initChart(canvas, width, height, dpr) {
      const chartInstance = echarts.init(canvas, null, {
        width,
        height,
        devicePixelRatio: dpr // 像素
      })
      canvas.setChart(this.chartInstance)
      chartInstance.setOption(this.ec.option || {})
        
      return chartInstance
    }
}

1.2 用initChart全局替换this.ec.onInit

• 修改initByOldWay和initByNewWay两个方法

methods: {
	initByOldWay(callback) {
		//...其余逻辑
		else if ( this.ec ) {
            this.chart = this.initChart(
              canvas,
              res.width,
              res.height,
              canvasDpr
            )
        }
       //...其余逻辑
	},
	initByNewWay(callback) {
		//...其余逻辑
		else if (this.ec) {
            this.chart = this.initChart(
              canvas,
              canvasWidth,
              canvasHeight,
              canvasDpr
            )
         }
		//...其余逻辑
	}
}

1.3 监听数据变化

• 阅读initChart方法，可知我们现在的图表数据是从props中的ec来的，ec是个对象，有一个option的键。对这个option监听即可:

注:这里没必要使用深度监听，外部组件使用时，如果图表数据的值有变化，直接将有变化的部分直接赋值给option即可，而不是通过option.xxx去修改数据。
如果想要通过option.xxx去修改数据，那么就需要深度监听了。

export default {
	//...其余代码
	watch: {
    	"ec.option"(val) {
      		if(!this.chart) return
      		this.chart.setOption(val)
    	}
  	},
	//...其余代码
}

1.4 ec-canvas完整代码参考

<template>
  <uni-shadow-root class="ec-canvas-ec-canvas">
    <canvas
      v-if="isUseNewCanvas"
      type="2d"
      class="ec-canvas"
      :canvas-id="canvasId"
      @init="init"
      @touchstart="touchStart"
      @touchmove="touchMove"
      @touchend="touchEnd"
    >
    </canvas>

    <canvas
      v-else
      class="ec-canvas"
      :canvas-id="canvasId"
      @init="init"
      @touchstart="touchStart"
      @touchmove="touchMove"
      @touchend="touchEnd"
    >
    </canvas>
  </uni-shadow-root>
</template>

<script>
import WxCanvas from './wx-canvas'
import * as echarts from './echarts.min.js'

let ctx

function compareVersion(v1, v2) {
  v1 = v1.split('.')
  v2 = v2.split('.')
  const len = Math.max(v1.length, v2.length)

  while (v1.length < len) {
    v1.push('0')
  }
  while (v2.length < len) {
    v2.push('0')
  }

  for (let i = 0; i < len; i++) {
    const num1 = parseInt(v1[i])
    const num2 = parseInt(v2[i])

    if (num1 > num2) {
      return 1
    } else if (num1 < num2) {
      return -1
    }
  }
  return 0
}

function wrapTouch(event) {
  for (let i = 0; i < event.touches.length; ++i) {
    const touch = event.touches[i]
    touch.offsetX = touch.x
    touch.offsetY = touch.y
  }
  return event
}
export default {
  props: {
    canvasId: {
      type: String,
      value: 'ec-canvas',
    },

    ec: {
      type: Object,
    },

    forceUseOldCanvas: {
      type: Boolean,
      value: false,
    },
  },
  data() {
    return {
      isUseNewCanvas: false,
    }
  },
  watch: {
    "ec.option"(val) {
      if(!this.chart) return
      this.chart.setOption(val)
    }
  },
  onReady: function () {
    // Disable prograssive because drawImage doesn't support DOM as parameter
    // See https://developers.weixin.qq.com/miniprogram/dev/api/canvas/CanvasContext.drawImage.html
    echarts.registerPreprocessor((option) => {
      if (option && option.series) {
        if (option.series.length > 0) {
          option.series.forEach((series) => {
            series.progressive = 0
          })
        } else if (typeof option.series === 'object') {
          option.series.progressive = 0
        }
      }
    })

    if (!this.ec) {
      console.warn(
        '组件需绑定 ec 变量，例： +
          'canvas-id="mychart-bar" ec="{{ ec }}">'
      )
      return
    }

    if (!this.ec.lazyLoad) {
      this.init()
    }
  },
  methods: {
    init: async function (callback) {
      const version = wx.getSystemInfoSync().SDKVersion

      const canUseNewCanvas = compareVersion(version, '2.9.0') >= 0
      const forceUseOldCanvas = this.forceUseOldCanvas
      const isUseNewCanvas = canUseNewCanvas && !forceUseOldCanvas
      this.isUseNewCanvas = isUseNewCanvas

      if (forceUseOldCanvas && canUseNewCanvas) {
        console.warn('开发者强制使用旧canvas,建议关闭')
      }
      await this.$nextTick()
      if (isUseNewCanvas) {
        // console.log('微信基础库版本大于2.9.0，开始使用');
        // 2.9.0 可以使用 
        this.initByNewWay(callback)
      } else {
        const isValid = compareVersion(version, '1.9.91') >= 0
        if (!isValid) {
          console.error(
            '微信基础库版本过低，需大于等于 1.9.91。' +
              '参见：https://github.com/ecomfe/echarts-for-weixin' +
              '#%E5%BE%AE%E4%BF%A1%E7%89%88%E6%9C%AC%E8%A6%81%E6%B1%82'
          )
          return
        } else {
          console.warn(
            '建议将微信基础库调整大于等于2.9.0版本。升级后绘图将有更好性能'
          )
          this.initByOldWay(callback)
        }
      }
    },
    initChart(canvas, width, height, dpr) {
      const chartInstance = echarts.init(canvas, null, {
        width,
        height,
        devicePixelRatio: dpr // 像素
      })
      canvas.setChart(this.chartInstance)
      chartInstance.setOption(this.ec.option || {})
        
      return chartInstance
    },
    initByOldWay(callback) {
      // 1.9.91 <= version < 2.9.0：原来的方式初始化
      ctx = wx.createCanvasContext(this.canvasId, this)
      const canvas = new WxCanvas(ctx, this.canvasId, false)

      echarts.setCanvasCreator(() => {
        return canvas
      })
      // const canvasDpr = wx.getSystemInfoSync().pixelRatio // 微信旧的canvas不能传入dpr
      const canvasDpr = 1
      var query = wx.createSelectorQuery().in(this)
      query
        .select('.ec-canvas')
        .boundingClientRect((res) => {
          if (typeof callback === 'function') {
            this.chart = callback(canvas, res.width, res.height, canvasDpr)
          } else if ( this.ec ) {
            this.chart = this.initChart(
              canvas,
              res.width,
              res.height,
              canvasDpr
            )
          } else {
            this.triggerEvent('init', {
              canvas: canvas,
              width: res.width,
              height: res.height,
              canvasDpr: canvasDpr, // 增加了dpr，可方便外面echarts.init
            })
          }
        })
        .exec()
    },

    initByNewWay(callback) {
      // version >= 2.9.0：使用新的方式初始化
      const query = wx.createSelectorQuery().in(this)
      query
        .select('.ec-canvas')
        .fields({ node: true, size: true })
        .exec((res) => {
          const canvasNode = res[0].node
          this.canvasNode = canvasNode

          const canvasDpr = wx.getSystemInfoSync().pixelRatio
          const canvasWidth = res[0].width
          const canvasHeight = res[0].height

          const ctx = canvasNode.getContext('2d')

          const canvas = new WxCanvas(ctx, this.canvasId, true, canvasNode)
          echarts.setCanvasCreator(() => {
            return canvas
          })

          if (typeof callback === 'function') {
            this.chart = callback(canvas, canvasWidth, canvasHeight, canvasDpr)
          } else if (
            this.ec
          ) {
            this.chart = this.initChart(
              canvas,
              canvasWidth,
              canvasHeight,
              canvasDpr
            )
          } else {
            this.triggerEvent('init', {
              canvas: canvas,
              width: canvasWidth,
              height: canvasHeight,
              dpr: canvasDpr,
            })
          }
        })
    },
    canvasToTempFilePath(opt) {
      if (this.isUseNewCanvas) {
        // 新版
        const query = wx.createSelectorQuery().in(this)
        query
          .select('.ec-canvas')
          .fields({ node: true, size: true })
          .exec((res) => {
            const canvasNode = res[0].node
            opt.canvas = canvasNode
            wx.canvasToTempFilePath(opt)
          })
      } else {
        // 旧的
        if (!opt.canvasId) {
          opt.canvasId = this.canvasId
        }
        ctx.draw(true, () => {
          wx.canvasToTempFilePath(opt, this)
        })
      }
    },

    touchStart(e) {
      if (this.chart && e.touches.length > 0) {
        var touch = e.touches[0]
        var handler = this.chart.getZr().handler
        handler.dispatch('mousedown', {
          zrX: touch.x,
          zrY: touch.y,
          preventDefault: () => {},
          stopImmediatePropagation: () => {},
          stopPropagation: () => {},
        })
        handler.dispatch('mousemove', {
          zrX: touch.x,
          zrY: touch.y,
          preventDefault: () => {},
          stopImmediatePropagation: () => {},
          stopPropagation: () => {},
        })
        handler.processGesture(wrapTouch(e), 'start')
      }
    },

    touchMove(e) {
      if (this.chart && e.touches.length > 0) {
        var touch = e.touches[0]
        var handler = this.chart.getZr().handler
        handler.dispatch('mousemove', {
          zrX: touch.x,
          zrY: touch.y,
          preventDefault: () => {},
          stopImmediatePropagation: () => {},
          stopPropagation: () => {},
        })
        handler.processGesture(wrapTouch(e), 'change')
      }
    },

    touchEnd(e) {
      if (this.chart) {
        const touch = e.changedTouches ? e.changedTouches[0] : {}
        var handler = this.chart.getZr().handler
        handler.dispatch('mouseup', {
          zrX: touch.x,
          zrY: touch.y,
          preventDefault: () => {},
          stopImmediatePropagation: () => {},
          stopPropagation: () => {},
        })
        handler.dispatch('click', {
          zrX: touch.x,
          zrY: touch.y,
          preventDefault: () => {},
          stopImmediatePropagation: () => {},
          stopPropagation: () => {},
        })
        handler.processGesture(wrapTouch(e), 'end')
      }
    },
  },
}
</script>
<style scoped>
.ec-canvas {
  width: 100%;
  height: 100%;
}
</style>

二、H5 echarts组件

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• 其实就是平时正常使用echarts，取名为ec-h5，直接上代码：

<template>
  <view class="h5-chart-container" :id="id"></view>
</template>

<script>
  import * as echarts from './echarts.min.js'
  export default {
    props: {
      id: {
        type: String,
        default: 'ec-h5-id'
      },
      option: {
        type: Object,
        default: () => {}
      }
    },
    watch: {
      option(val) {
        if(!this.chart) return
        this.chart.setOption(val)
      }
    },
    data() {
      return {}
    },
    mounted() {
      this.initChart()
    },
    methods: {
      initChart() {
        const chartDom = document.getElementById(this.id)
        this.chart = echarts.init(chartDom)
        this.chart.setOption(this.option)
      }
    }
  }
</script>

<style scoped>
.h5-chart-container {
  height: 100%;
  width: 100%;
}
</style>

三、供外部调用的组件

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外部调用组件 uni-chart代码

• 取名为uni-chart，通过条件编译的方式，由这个组件判断是微信还是H5。

<template>
  <!--  #ifdef  MP-WEIXIN -->
  <ec-canvas :ec="{option}" :canvasId="id" />
  <!--  #endif -->

  <!--  #ifdef  H5 -->
  <ec-h5 :option="option" :id="id" />
  <!--  #endif -->
</template>

<script>
  import ecCanvas from './ec-canvas.vue';
  import ecH5 from './ec-h5.vue'

  export default {
    props: {
      id: {
        type: String,
        default: 'uni-chart-id'
      },
      option: {
        type: Object,
        default: () => {}
      }
    },
    components: {
      ecCanvas,
      ecH5
    },
  }
</script>

使用uni-chart

• 参考:

<template>
  <view class="parent-container">
    <uni-chart class="my-chart" :option="option" />
  </view>
</template>

<script>
import uniChart from './components/uni-chart.vue'
export default {
  components: {
    uniChart,
  },
  data() {
    return {
      option: {
        xAxis: {
          type: 'category',
          data: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'],
        },
        yAxis: {
          type: 'value',
        },
        series: [
          {
            data: [120, 200, 150, 80, 70, 110, 130],
            type: 'bar',
          },
        ],
      },
    }
  },
  mounted() {
    // 动态更新图表数据
    setTimeout(() => {
      this.option = {
        series: [
          {
            data: [12, 20, 15, 8, 7, 11, 13],
            color: ['red']
          },
        ],
      }
    }, 2000)
  },
}
</script>
<style scoped>
.parent-container {
  height: 100vh;
}
.my-chart {
  height: 600rpx;
}
</style>

碎碎念：微信小程序主包限制有2MB，所以这个组件不好放于根目录下的components，这样会被打到主包里，所以创个分包，将图表相关的业务组件都丢到这个分包去，这样最好。
分包也能有static文件夹，但是我丢进去之后，uni还是会重复打包，导致分包什么都没有，就有2MB大小。