circle-text-svg.vue

<template>
  <svg
    xmlns="http://www.w3.org/2000/svg"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    :viewBox="viewBox"
    :style="{ maxWidth: boxSize + 'px' }"
  >
    <title v-text="text" />
    <defs>
      <path
        id="textcircle"
        :d="circlePath"
      />
    </defs>
    <text :font-size="fontSize">
      <textPath xlink:href="#textcircle" v-text="repeatedAroundText" />
    </text>
  </svg>
</template>

<script>
/*
 * thanks: https://tyru.github.io/svg-circle-misc-algorithm/
 */

const SEGMENTS = 8
const ANGLE = 2 * Math.PI / SEGMENTS
const HALF_ANGLE_RATIO = Math.tan(ANGLE / 2)

function range(from, to) {
  const length = to - from
  return Array.from({ length: length + 1 }, (v, k) => k + from)
}

function drawCirclePath(center, radius) {
  const anchorX = theta => radius * Math.cos(theta)
  const anchorY = theta => radius * Math.sin(theta)
  const controlX = theta => anchorX(theta) + radius * HALF_ANGLE_RATIO * Math.cos(theta - Math.PI / 2)
  const controlY = theta => anchorY(theta) + radius * HALF_ANGLE_RATIO * Math.sin(theta - Math.PI / 2)
  return [
    ['M', center + radius, center],
    ...range(1, SEGMENTS).map((index) => {
      const theta = index * ANGLE
      return ['Q', controlX(theta) + center, controlY(theta) + center, anchorX(theta) + center, anchorY(theta) + center]
    })
  ]
}

export default {
  props: {
    text: {
      type: String,
      default: ''
    },
    fontSize: {
      type: Number,
      default: 12
    },
    boxSize: {
      type: Number,
      default: 800
    }
  },
  data() {
    return {}
  },
  computed: {
    centerPosition() {
      return Math.floor(this.boxSize / 2)
    },
    radius() {
      return Math.floor(this.boxSize / 2) - this.fontSize * 2
    },
    viewBox() {
      return [0, 0, this.boxSize, this.boxSize].join(' ')
    },
    repeatedAroundText() {
      const repeatCount = Math.ceil((this.radius * 2 * Math.PI) / this.fontSize / this.text.length)
      return this.text.repeat(repeatCount)
    },
    circlePath() {
      const circlePath = drawCirclePath(this.centerPosition, this.radius)
      return circlePath.map(path => path[0] + path.slice(1).join(',')).join(' ')
    }
  }
}
</script>