vue自定義開發滑動圖片驗證元件

<template>
  <div class="verification" ref="verification">
    <!-- 畫布部分 -->
    <canvas ref="slideVerify" class="slide-img"></canvas>
    <div style="display:none">
      <img ref="imgs" :src="imgList[imgIndex]"/>
    </div>
    <!-- 下面滾軸部分 -->
    <div class="slide-wrapper bg-start">
      <!-- 滾軸 -->
      <div class="btn" ref="btn" @mousedown="mouseDown" @mouseup="mouseUp"></div>
      <p class="text" ref="text">{{content}}</p>
      <div class="bg" ref="bg"></div>
    </div>
    <!-- 重新整理按鈕 -->
    <button class="refresh" @click="refresh"></button>
  </div>
</template>

<script>
export default {
  data () {
    return {
      imgIndex: 0,
      blockCanvas: null,
      imgList: [require('../assets/1.png'),
        require('../assets/3.png'),
        require('../assets/4.png'),
        require('../assets/5.png') ],
      content: '滑動滾軸',
      isDown: false, // 滑鼠是否按下
      btnX: 0, 
      imgX: 0 
    }
  },
  mounted () {
    this.imgIndex = this.randomNumber(0, 4)
    document.addEventListener('mousemove', this.mouseMove)
    this.imageCanvas()
  },
  methods: {
    // 生成亂數字
    randomNumber (min, max) {
      return Math.floor(Math.random() * (max - min) + min)
    },
    // 滑鼠按下時
    mouseDown (e) {
      this.isDown = true
      this.btnX = e.clientX - this.$refs.btn.offsetLeft
    },
    // 滑鼠滑動時
    mouseMove (e) {
      // 滾軸左端向右邊移動的距離
      let moveX = e.clientX - this.btnX
      if (this.isDown) {
        // 滾軸滑動時不能超過的距離
        if (this.$refs.btn.offsetLeft <= 259 && this.$refs.btn.offsetLeft >= 0) {
          this.$refs.btn.style.left = `${moveX}px`
          this.blockCanvas.style.left = `${moveX - this.imgX}px`
          this.$refs.bg.style.width = `${moveX}px`
        }
      }
    },
    // 滑動中鬆開
    mouseUp () {
      let leftX = this.$refs.btn.offsetLeft
      // 方塊的位置和缺失的位置重合允許左右2px的誤差
      if (this.imgX >= leftX - 1 && this.imgX <= leftX + 1) {
        // 滑動成功時的邏輯
        this.$refs.btn.classList.add('btnsuccess')
        this.isDown = false
      }
      // 如果滑動失敗，滾軸自動回到左邊
      if (this.isDown) {
        this.$refs.btn.style.left = 0
        this.blockCanvas.style.left = `-${this.imgX}px`
        this.$refs.bg.style.width = 0
      }
      // 開關原則
      this.isDown = false
    },
    // 畫圖
    imageCanvas () {
      this.blockCanvas = this.blockCanvas ? this.blockCanvas.remove() : null
      this.blockCanvas = this.createCanvas(300, 150)
      this.$refs.verification.insertBefore(this.blockCanvas, this.$refs.slideVerify)
      let x = this.randomNumber(60, 200)
      let y = 40
      this.imgX = x
      let c = this.$refs.slideVerify
      let bg = c.getContext('2d')
      let img = this.$refs.imgs
      let bk = this.blockCanvas.getContext('2d')
      // 在兩塊畫布上都放上相同的圖片
      img.onload = () => {
        bg.drawImage(img, 0, 0)
        bk.drawImage(img, 0, 0)
      }
      this.drawBlock(bg, x, y, 'fill')
      this.drawBlock(bk, x, y, 'clip')
    },
    // 畫摳出來的方塊
    drawBlock (ctx, x, y, type) {
      ctx.beginPath()
      ctx.moveTo(x, y)
      ctx.arc(x + 42 / 2, y - 9 + 2, 9, 0.72 * Math.PI, 2.26 * Math.PI)
      ctx.lineTo(x + 42, y)
      ctx.arc(x + 42 + 9 - 2, y + 42 / 2, 9, 1.21 * Math.PI, 2.78 * Math.PI)
      ctx.lineTo(x + 42, y + 42)
      ctx.lineTo(x, y + 42)
      ctx.arc(x + 9 - 2, y + 42 / 2, 9 + 0.4, 2.76 * Math.PI, 1.24 * Math.PI, true)
      ctx.lineTo(x, y)
      ctx.lineWidth = 2
      ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
      ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
      ctx.stroke()
      ctx[type]()
      ctx.globalCompositeOperation = 'destination-over'
      // 解決進入頁面時不自動扣拼圖樣式的麻煩(有時需要滑鼠點選後才會出現裁剪後的拼圖)
      this.blockCanvas.style.left = `-${x}px`
    },
    // 重新整理
    refresh () {
      // 有時會出現點選重新整理，randomNumber返回的數位和上次儲存的一樣，畫布清空後但是填充時沒有改變；所以當一樣時，不會執行重新整理操作
      if (this.imgIndex == this.randomNumber(0, 4)) {
        return false
      }
      this.clean()
      this.$refs.btn.style.left = 0
      this.$refs.bg.style.width = 0
      this.$refs.btn.classList.remove('btnsuccess')
      this.isDown = false // 滑鼠是否按下
      this.btnX = 0 // 滑鼠點選的水平位置與滾軸移動水平位置的差
      this.imgX = 0
      this.imageCanvas('restore')
      this.imgIndex = this.randomNumber(0, 4)
    },
    // 清空canvas
    clean () {
      let cxt2 = this.$refs.slideVerify.getContext('2d')
      cxt2.clearRect(0, 0, 300, 150)
    },
    // 新建canvas
    createCanvas (width, height) {
      const canvas = document.createElement('canvas')
      canvas.width = width
      canvas.height = height
      canvas.style.position = 'absolute'
      return canvas
    }
  }
}
</script>

<style scoped>
.verification {
  position: relative;
  width: 300px;
  margin: 0 auto;
}
.slide-wrapper {
  position: relative;
  width: 300px;
  height: 40px;
}
.bg-start {
  background: cadetblue;
}
.bg {
  position: absolute;
  height: 40px;
  background: #ccc;
}
.text {
  position: absolute;
  width: 100%;
  height: 40px;
  text-align: center;
  line-height: 40px;
  margin: 0;
  /* z-index: 1; */
}
.text-success {
  color: white;
  z-index: 2;
}
.btn {
  position: absolute;
  width: 40px;
  height: 40px;
  z-index: 1;
  border-radius: 5px;
  background: rgb(143, 145, 148);
  text-align: center;
  font-size: 24px;
  color: white;
  box-shadow: 0 0 1px 1px #fff;
  background: #fff no-repeat center url("data:image/png;base64,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");
}
.btnsuccess {
  background: #fff no-repeat center url("data:image/png;base64,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");
}
.refresh {
    cursor: pointer;
    width: 20px;
    height: 20px;
    position: absolute;
    z-index: 1;
    top: 0;
    right: 10px;
    opacity: .6;
    background: url('../assets/ref.jpg') no-repeat;
    background-size: cover;
}
</style>