cfc/cfc-frontend/components/TrendChart.vue

<template>
  <view class="trend-chart-wrap">
    <view class="trend-container" :style="containerStyle">
      <canvas :id="canvasId" type="2d" class="trend-canvas" :style="canvasStyle"></canvas>
      <view class="trend-tap-layer" @click="onCanvasTap"></view>
    </view>
    <view class="trend-legend" v-if="series.length > 1">
      <view class="legend-item" v-for="(s, i) in series" :key="getItemKey(s, i)">
        <view class="legend-line" :style="'border-color:' + s.color"></view>
        <text class="legend-text">{{ s.name }}</text>
      </view>
    </view>
  </view>
</template>

<script>
/**
 * TrendChart - 多序列折线图 Canvas 组件
 * 用法：<TrendChart :series="[{name,color,points:[{reportDate,value,unit}]}]" height="360" />
 * 参照 RadarChart.vue 的 type=2d + DPR + 重试初始化模式。
 */
export default {
  props: {
    /** 序列数组 [{ name, color, points:[{reportDate,value,unit}] }] */
    series: { type: Array, default: function() { return [] } },
    width: { type: Number, default: 690 },
    height: { type: Number, default: 420 },
    /** Y 轴自动范围下界（默认 min-5%） */
    yMin: { type: Number, default: 0 },
    /** 是否绘制数据点数值标注 */
    showValues: { type: Boolean, default: true }
  },
  data: function() {
    return {
      canvasReady: false, canvasWidth: 0, canvasHeight: 0, ctx: null, dpr: 1,
      _canvasNode: null, _canvasLeft: 0, _canvasTop: 0,
      _destroyed: false, _initTimer: null,
      canvasId: 'trendCanvas_' + (this._uid || 0)
    }
  },
  computed: {
    containerStyle: function() { return 'width:' + this.width + 'rpx;height:' + this.height + 'rpx' },
    canvasStyle: function() { return 'width:' + this.width + 'rpx;height:' + this.height + 'rpx' }
  },
  watch: {
    series: { handler: function() { if (this.canvasReady) this._doRender() }, deep: true }
  },
  mounted: function() {
    var self = this
    var retryCount = 0
    var maxRetry = 5
    function tryInit() {
      if (self._destroyed) return
      self.initCanvas(function(success) {
        if (self._destroyed) return
        if (!success && retryCount < maxRetry) {
          retryCount++
          self._initTimer = setTimeout(tryInit, 60)
        } else if (!success) {
          console.log('[TrendChart] 初始化失败，重试 ' + maxRetry + ' 次后放弃', self.canvasId)
        }
      })
    }
    self._initTimer = setTimeout(tryInit, 100)
  },
  beforeDestroy: function() {
    this._destroyed = true
    if (this._initTimer) { clearTimeout(this._initTimer); this._initTimer = null }
  },
  methods: {
    getItemKey: function(s, i) { return (s && s.name) || i },

    initCanvas: function(cb) {
      var self = this
      uni.createSelectorQuery().in(this)
        .select('#' + this.canvasId)
        .fields({ node: true, size: true, rect: true })
        .exec(function(res) {
          try {
            if (self._destroyed) return
            if (!res || !res[0] || !res[0].node) { if (cb) cb(false); return }
            var info = res[0]
            var canvas = info.node
            var width = info.width
            var height = info.height
            if (!width || !height) {
              var winWidth = 375
              try { winWidth = uni.getWindowInfo().windowWidth || 375 } catch (e) {}
              width = Math.round((self.width || 690) * winWidth / 750)
              height = Math.round((self.height || 420) * winWidth / 750)
            }
            var pixelRatio = 2
            try { pixelRatio = uni.getWindowInfo().pixelRatio || 2 } catch (e) {}
            canvas.width = width * pixelRatio
            canvas.height = height * pixelRatio
            var ctx = canvas.getContext('2d')
            if (!ctx) { if (cb) cb(false); return }
            ctx.scale(pixelRatio, pixelRatio)
            self.ctx = ctx
            self._canvasNode = canvas
            self.canvasWidth = width
            self.canvasHeight = height
            self.dpr = pixelRatio
            self._canvasLeft = info.left || 0
            self._canvasTop = info.top || 0
            self.canvasReady = true
            self._doRender()
            if (cb) cb(true)
          } catch (e) {
            console.log('[TrendChart] initCanvas 回调异常', e)
            if (cb) cb(false)
          }
        })
    },

    _safeSeries: function(arr) {
      if (!Array.isArray(arr)) return []
      return arr.filter(function(s) { return s && Array.isArray(s.points) && s.points.length > 0 })
    },

    /** 计算 X 轴时间范围与 Y 轴数值范围 */
    _computeRanges: function(seriesList) {
      var min = Infinity, max = -Infinity, firstDate = null, lastDate = null
      seriesList.forEach(function(s) {
        s.points.forEach(function(p) {
          var v = parseFloat(p.value)
          if (!isNaN(v)) { if (v < min) min = v; if (v > max) max = v }
          if (!firstDate || p.reportDate < firstDate) firstDate = p.reportDate
          if (!lastDate || p.reportDate > lastDate) lastDate = p.reportDate
        })
      })
      if (min === Infinity) { min = 0; max = 1 }
      if (max === min) { max = min + 1 }
      var pad = (max - min) * 0.08
      return { yMin: Math.max(0, min - pad), yMax: max + pad, firstDate: firstDate, lastDate: lastDate }
    },

    _doRender: function() {
      if (!this.ctx) return
      var self = this
      var ctx = this.ctx
      var w = this.canvasWidth, h = this.canvasHeight
      var padL = 34, padR = 14, padT = 16, padB = 26
      var plotW = w - padL - padR, plotH = h - padT - padB
      var seriesList = this._safeSeries(this.series)
      if (seriesList.length === 0) {
        ctx.clearRect(0, 0, w, h)
        ctx.fillStyle = '#94A3B8'
        ctx.font = '12px sans-serif'
        ctx.textAlign = 'center'
        ctx.fillText('暂无趋势数据', w / 2, h / 2)
        return
      }
      var ranges = this._computeRanges(seriesList)
      var yMin = ranges.yMin, yMax = ranges.yMax
      function yOf(v) { return padT + plotH * (1 - (v - yMin) / (yMax - yMin)) }
      // 日期横轴：按所有序列全部点排序后均分
      var allDates = []
      seriesList.forEach(function(s) {
        s.points.forEach(function(p) {
          if (allDates.indexOf(p.reportDate) < 0) allDates.push(p.reportDate)
        })
      })
      allDates.sort()
      function xOf(dateStr) {
        if (allDates.length <= 1) return padL + plotW / 2
        var idx = allDates.indexOf(dateStr)
        if (idx < 0) return padL
        return padL + plotW * (allDates.length === 1 ? 0.5 : idx / (allDates.length - 1))
      }

      ctx.clearRect(0, 0, w, h)
      // 网格（4 条横线 + 2 条纵线）
      ctx.strokeStyle = '#EEF2F7'
      ctx.lineWidth = 1
      for (var gi = 0; gi <= 3; gi++) {
        var gy = padT + plotH * (gi / 3)
        ctx.beginPath()
        ctx.moveTo(padL, gy); ctx.lineTo(w - padR, gy)
        ctx.stroke()
      }
      // Y 轴刻度文字
      ctx.fillStyle = '#94A3B8'
      ctx.font = '10px sans-serif'
      ctx.textAlign = 'right'
      for (var ti = 0; ti <= 3; ti++) {
        var tv = yMin + (yMax - yMin) * (1 - ti / 3)
        var ty = padT + plotH * (ti / 3)
        ctx.fillText(self._fmtNum(tv), padL - 4, ty + 3)
      }
      // 折线 + 数据点 + 数值
      var palette = ['#F97316', '#0EA5E9', '#10B981', '#8B5CF6', '#EF4444', '#F59E0B']
      seriesList.forEach(function(s, si) {
        var color = s.color || palette[si % palette.length]
        ctx.strokeStyle = color
        ctx.lineWidth = 2
        ctx.beginPath()
        var started = false
        s.points.forEach(function(p) {
          var v = parseFloat(p.value)
          if (isNaN(v)) return
          var x = xOf(p.reportDate), y = yOf(v)
          if (!started) { ctx.moveTo(x, y); started = true } else { ctx.lineTo(x, y) }
        })
        ctx.stroke()
        // 数据点 + 值
        s.points.forEach(function(p) {
          var v = parseFloat(p.value)
          if (isNaN(v)) return
          var x = xOf(p.reportDate), y = yOf(v)
          ctx.fillStyle = color
          ctx.beginPath(); ctx.arc(x, y, 3.5, 0, 2 * Math.PI); ctx.fill()
          if (self.showValues) {
            ctx.fillStyle = '#475569'
            ctx.font = '10px sans-serif'
            ctx.textAlign = 'center'
            ctx.fillText(self._fmtValue(p), x, y - 8)
          }
        })
        // 序列名（最右端上方）
        ctx.fillStyle = color
        ctx.font = '11px sans-serif'
        ctx.textAlign = 'right'
        var last = s.points[s.points.length - 1]
        if (last && !isNaN(parseFloat(last.value))) {
          ctx.fillText(s.name || '', xOf(last.reportDate), yOf(parseFloat(last.value)) - 14)
        }
      })
      // X 轴日期标签（首/中/末）
      ctx.fillStyle = '#94A3B8'
      ctx.font = '10px sans-serif'
      ctx.textAlign = 'center'
      if (allDates.length > 0) {
        ctx.fillText(String(allDates[0]).slice(5), padL, h - 8)
        if (allDates.length > 1) {
          var midIdx = Math.floor((allDates.length - 1) / 2)
          ctx.fillText(String(allDates[midIdx]).slice(5), padL + plotW * (midIdx / (allDates.length - 1)), h - 8)
          ctx.fillText(String(allDates[allDates.length - 1]).slice(5), w - padR, h - 8)
        }
      }
    },

    _fmtNum: function(v) {
      if (v >= 100) return Math.round(v) + ''
      if (v >= 10) return v.toFixed(1)
      return v.toFixed(2)
    },
    _fmtValue: function(p) {
      var v = parseFloat(p.value)
      if (isNaN(v)) return '--'
      return this._fmtNum(v) + (p.unit ? p.unit : '')
    },

    onCanvasTap: function(e) {
      // 一期无点击交互需求，预留：点击最近数据点可 emit 'pointTap'
      this.$emit('chartTap')
    }
  }
}
</script>

<style scoped>
.trend-chart-wrap {
  display: flex;
  flex-direction: column;
}
.trend-container {
  position: relative;
}
.trend-canvas {
  display: block;
}
.trend-tap-layer {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
}
.trend-legend {
  display: flex;
  flex-direction: row;
  flex-wrap: wrap;
  justify-content: center;
  padding-top: 12rpx;
}
.legend-item {
  display: flex;
  flex-direction: row;
  align-items: center;
  margin: 0 16rpx 8rpx;
}
.legend-line {
  width: 32rpx;
  border-top: 4rpx solid #0EA5E9;
  margin-right: 8rpx;
}
.legend-text {
  font-size: 22rpx;
  color: #475569;
}
</style>