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本篇內容介紹了“uniapp封裝小程序雷達圖組件的用法”的有關知識，在實際案例的操作過程中，不少人都會遇到這樣的困境，接下來就讓小編帶領大家學習一下如何處理這些情況吧！希望大家仔細閱讀，能夠學有所成！
view
<canvas id="radar-canvas" class="radar-canvas" type="2d"></canvas>
style
.radar-canvas width 550rpx height 550rpx margin 0 auto
script
<script>
import { toRpx } from "@/utils/common"
const numCount = 5 //元素個數
const numSlot = 4 //一條線上的總節點數
const mW = toRpx(275) //Canvas的寬度
const mCenter = mW / 2 //中心點
const mAngle = Math.PI * 2 / numCount //角度
const mRadius = mCenter - toRpx(43) //半徑(減去的值用于給繪制的文本留空間)
let canvas = null // canvas
let canvasCtx = null // canvas context
export default {
name: 'RadarChart',
props: {
},
methods: {
// 初始化雷達圖，在組件掛載的時候執行
initDrawRadar() {
console.log('init')
const query = uni.createSelectorQuery().in(this)
query.select('#radar-canvas').fields({ node: true, size: true }).exec((res) => {
canvas = res[0].node
canvasCtx = canvas.getContext('2d')
const dpr = uni.getSystemInfoSync().pixelRatio
canvas.width = res[0].width * dpr
canvas.height = res[0].height * dpr
canvasCtx.scale(dpr, dpr)
})
},
// 開始執行繪制
handleDraw(radarData) {
this.drawEdge()
this.drawLinePoint()
this.drawText(radarData)
this.drawSubText(radarData)
this.drawEdgeDot()
this.drawRegion(radarData, 'rgba(255, 105, 81, 0.4)')
},
// 繪制圓邊
drawEdge() {
canvasCtx.strokeStyle = '#EEEEEE'
for (let i = 0; i < numSlot; i++) {
// 計算半徑
let radius = mRadius / numSlot * (i + 1)
if (i === 3) {
canvasCtx.lineWidth = toRpx(4) // 設置線寬
canvasCtx.beginPath()
canvasCtx.arc(mCenter, mCenter, radius, 0, 2 * Math.PI,) // 開始畫圓
canvasCtx.stroke()
} else {
canvasCtx.lineWidth = toRpx(1)
const space = 60 + 10 * (i+1)
this.drawDashCircle(mCenter, mCenter, radius, space)
}
}
},
// 繪制外邊框圓點
drawEdgeDot(x, y) {
canvasCtx.fillStyle = '#EEEEEF'
canvasCtx.beginPath()
for (let k = 0; k < numCount; k++) {
let x = mCenter + mRadius * Math.cos(mAngle * k - Math.PI / 2)
let y = mCenter + mRadius * Math.sin(mAngle * k - Math.PI / 2)
canvasCtx.arc(x, y, toRpx(5), Math.PI * 2, 0, true)
canvasCtx.closePath()
}
canvasCtx.fill()
},
// 繪制虛線圓
drawDashCircle(x, y, radius, space = 100) {
const gap = 2 * Math.PI / space
canvasCtx.lineCap ='square'
let start = 0; //從原點開始畫
while (start <= 2 * Math.PI) {
let end = start + gap
canvasCtx.beginPath() //開始一個新的路徑
canvasCtx.arc(x, y, radius, start, end, false)
start = gap + end
canvasCtx.stroke() //對當前路徑進行描邊
}
},
// 繪制連接點
drawLinePoint() {
canvasCtx.lineWidth = toRpx(1)
canvasCtx.beginPath()
for (let k = 0; k < numCount; k++) {
let x = mCenter + mRadius * Math.cos(mAngle * k - Math.PI / 2)
let y = mCenter + mRadius * Math.sin(mAngle * k - Math.PI / 2)
canvasCtx.moveTo(mCenter, mCenter)
canvasCtx.lineTo(x, y)
}
canvasCtx.stroke()
},
// 繪制文本信息
drawText(mData) {
canvasCtx.fillStyle = '#222325'
canvasCtx.font = `bold ${toRpx(14)}px PingFangSC-Medium, PingFang SC` //設置字體
for (let n = 0; n < numCount; n++) {
let x = mCenter + mRadius * Math.cos(mAngle * n - Math.PI / 2)
let y = mCenter + mRadius * Math.sin(mAngle * n - Math.PI / 2)
//通過不同的位置，調整文本的顯示位置
const text = mData[n][0]
if (n === 0) {
canvasCtx.fillText(text, x - toRpx(12), y - toRpx(30))
}
if (n === 1) {
canvasCtx.fillText(text, x + toRpx(12), y)
}
if (n === 2) {
canvasCtx.fillText(text, x + toRpx(12), y + toRpx(20))
}
if (n === 3) {
canvasCtx.fillText(text, x - toRpx(36), y + toRpx(20))
}
if (n === 4) {
canvasCtx.fillText(text, x - toRpx(40), y)
}
}
},
// 繪制文本信息
drawSubText(mData) {
canvasCtx.fillStyle = '#8D949B'
canvasCtx.font = `${toRpx(11)}px PingFangSC-Medium, PingFang SC` //設置字體
for (let n = 0; n < numCount; n++) {
const x = mCenter + mRadius * Math.cos(mAngle * n - Math.PI / 2)
const y = mCenter + mRadius * Math.sin(mAngle * n - Math.PI / 2)
//通過不同的位置，調整文本的顯示位置
const text = `(${mData[n][1]})`
if (n === 0) {
canvasCtx.fillText(text, x - canvasCtx.measureText(text).width / 2, y - toRpx(10))
}
if (n === 1) {
canvasCtx.fillText(text, x + canvasCtx.measureText(text).width, y + toRpx(16))
}
if (n === 2) {
canvasCtx.fillText(text, x + canvasCtx.measureText(text).width - toRpx(4), y + toRpx(40))
}
if (n === 3) {
canvasCtx.fillText(text, x - canvasCtx.measureText(text).width - toRpx(12), y + toRpx(40))
}
if (n === 4) {
canvasCtx.fillText(text, x - canvasCtx.measureText(text).width - toRpx(16), y + toRpx(16))
}
}
},
//繪制紅色數據區域(數據和填充顏色)
drawRegion(mData, color){
canvasCtx.strokeStyle = '#FF6951'
canvasCtx.lineWidth = toRpx(4) // 設置線寬
canvasCtx.beginPath()
for (let m = 0; m < numCount; m++){
let x = mCenter + mRadius * Math.cos(mAngle * m - Math.PI / 2) * mData[m][1] / 100
let y = mCenter + mRadius * Math.sin(mAngle * m - Math.PI / 2) * mData[m][1] / 100
canvasCtx.lineTo(x, y)
}
canvasCtx.closePath()
canvasCtx.fillStyle = color
canvasCtx.fill()
canvasCtx.stroke()
},
},
mounted() {
this.initDrawRadar()
}
}
</script>要注意的點是，這里是封裝成組件調用，在初始化的時候，const query = uni.createSelectorQuery().in(this)，要加上in(this)，否則會報找不到node節點的錯誤信息
export function toRpx(val) {
const res = uni.getSystemInfoSync()
const scaleRate = res.windowWidth / 375
return val * scaleRate
}在頁面中調用
<template>
<!--雷達圖-->
<radar-chart :radarData="radarData" ref="radarRef"></radar-chart>
</template>
import RadarChart from './components/radar'
export default {
components: {
RadarChart,
},
data() {
return {
radarData:[["聽力", 0], ["口語",0], ["語法",0], ["詞匯",0], ["閱讀",0]],
}
},
methods: {
getData() {
// 請求數據返回后，調用組件方法渲染
this.$refs.radarRef.handleDraw(this.radarData)
}
}
}“uniapp封裝小程序雷達圖組件的用法”的內容就介紹到這里了，感謝大家的閱讀。如果想了解更多行業相關的知識可以關注億速云網站，小編將為大家輸出更多高質量的實用文章！
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