feat: 签名组件

src/components/ESign/index.ts

+import ESign from './src/ESign.vue'
+
+export { ESign }

src/components/ESign/src/ESign.vue

+<template>
+  <div style="position: relative">
+    <canvas
+      ref="canvasRef"
+      @mousedown="mouseDown"
+      @mousemove="mouseMove"
+      @mouseup="mouseUp"
+      @touchstart="touchStart"
+      @touchmove="touchMove"
+      @touchend="touchEnd"
+      style="border: 1px solid lightgrey; max-width: 100%; display: block"
+    >
+    </canvas>
+
+    <el-button
+      style="position: absolute; bottom: 20px; right: 10px"
+      type="primary"
+      text
+      size="small"
+      @click="reset"
+    >
+      <Icon icon="ep:delete" class="mr-5px" />清除
+    </el-button>
+  </div>
+</template>
+
+<script lang="ts" setup>
+import { propTypes } from '@/utils/propTypes'
+
+defineOptions({ name: 'ESign' })
+
+const emits = defineEmits(['update:bgColor'])
+const props = defineProps({
+  // 画布宽度，即导出图片的宽度
+  width: propTypes.number.def(900),
+  // 画布高度，即导出图片的高度
+  height: propTypes.number.def(400),
+  // 画笔粗细
+  lineWidth: propTypes.number.def(10),
+  // 画笔颜色
+  lineColor: propTypes.string.def('#000000'),
+  // 画布背景色，为空时画布背景透明
+  bgColor: propTypes.string.def(''),
+  // 是否裁剪，在画布设定尺寸基础上裁掉四周空白部分
+  isCrop: propTypes.bool.def(false),
+  // 清空画布时是否同时清空设置的背景色
+  isClearBgColor: propTypes.bool.def(true),
+  // 生成图片格式
+  format: propTypes.string.def('image/png'),
+  // 生成图片质量，0 到 1
+  quality: propTypes.number.def(1)
+})
+const canvasRef = ref()
+const hasDrew = ref(false)
+const resultImg = ref('')
+const points = ref<any>([])
+const canvasTxt = ref()
+const startX = ref(0)
+const startY = ref(0)
+const isDrawing = ref(false)
+const sratio = ref(1)
+
+const ratio = computed(() => {
+  return props.height / props.width
+})
+const stageInfo = computed(() => {
+  return canvasRef.value.getBoundingClientRect()
+})
+const bgColor = computed(() => {
+  return props.bgColor ? props.bgColor : 'rgba(255, 255, 255, 0)'
+})
+
+watch(
+  () => bgColor.value,
+  () => {
+    if (canvasRef.value) {
+      canvasRef.value.style.background = bgColor.value
+    }
+  },
+  {
+    immediate: true
+  }
+)
+
+const resizeHandler = () => {
+  const canvas = canvasRef.value
+  canvas.style.width = props.width + 'px'
+  const realw = parseFloat(window.getComputedStyle(canvas).width)
+  canvas.style.height = ratio.value * realw + 'px'
+  canvasTxt.value = canvas.getContext('2d')
+  canvasTxt.value.scale(1 * sratio.value, 1 * sratio.value)
+  sratio.value = realw / props.width
+  canvasTxt.value.scale(1 / sratio.value, 1 / sratio.value)
+}
+// For PC
+const mouseDown = (e) => {
+  e.preventDefault()
+  isDrawing.value = true
+  hasDrew.value = true
+  let obj = {
+    x: e.offsetX,
+    y: e.offsetY
+  }
+  drawStart(obj)
+}
+const mouseMove = (e) => {
+  e.preventDefault()
+  if (isDrawing.value) {
+    let obj = {
+      x: e.offsetX,
+      y: e.offsetY
+    }
+    drawMove(obj)
+  }
+}
+const mouseUp = (e) => {
+  e.preventDefault()
+  let obj = {
+    x: e.offsetX,
+    y: e.offsetY
+  }
+  drawEnd(obj)
+  isDrawing.value = false
+}
+// For Mobile
+const touchStart = (e) => {
+  e.preventDefault()
+  hasDrew.value = true
+  if (e.touches.length === 1) {
+    let obj = {
+      x: e.targetTouches[0].clientX - canvasRef.value.getBoundingClientRect().left,
+      y: e.targetTouches[0].clientY - canvasRef.value.getBoundingClientRect().top
+    }
+    drawStart(obj)
+  }
+}
+const touchMove = (e) => {
+  e.preventDefault()
+  if (e.touches.length === 1) {
+    let obj = {
+      x: e.targetTouches[0].clientX - canvasRef.value.getBoundingClientRect().left,
+      y: e.targetTouches[0].clientY - canvasRef.value.getBoundingClientRect().top
+    }
+    drawMove(obj)
+  }
+}
+const touchEnd = (e) => {
+  e.preventDefault()
+  if (e.touches.length === 1) {
+    let obj = {
+      x: e.targetTouches[0].clientX - canvasRef.value.getBoundingClientRect().left,
+      y: e.targetTouches[0].clientY - canvasRef.value.getBoundingClientRect().top
+    }
+    drawEnd(obj)
+  }
+}
+// 绘制
+const drawStart = (obj) => {
+  startX.value = obj.x
+  startY.value = obj.y
+  canvasTxt.value.beginPath()
+  canvasTxt.value.moveTo(startX.value, startY.value)
+  canvasTxt.value.lineTo(obj.x, obj.y)
+  canvasTxt.value.lineCap = 'round'
+  canvasTxt.value.lineJoin = 'round'
+  canvasTxt.value.lineWidth = props.lineWidth * sratio.value
+  canvasTxt.value.stroke()
+  canvasTxt.value.closePath()
+  points.value.push(obj)
+}
+const drawMove = (obj) => {
+  canvasTxt.value.beginPath()
+  canvasTxt.value.moveTo(startX.value, startY.value)
+  canvasTxt.value.lineTo(obj.x, obj.y)
+  canvasTxt.value.strokeStyle = props.lineColor
+  canvasTxt.value.lineWidth = props.lineWidth * sratio.value
+  canvasTxt.value.lineCap = 'round'
+  canvasTxt.value.lineJoin = 'round'
+  canvasTxt.value.stroke()
+  canvasTxt.value.closePath()
+  startY.value = obj.y
+  startX.value = obj.x
+  points.value.push(obj)
+}
+const drawEnd = (obj) => {
+  canvasTxt.value.beginPath()
+  canvasTxt.value.moveTo(startX.value, startY.value)
+  canvasTxt.value.lineTo(obj.x, obj.y)
+  canvasTxt.value.lineCap = 'round'
+  canvasTxt.value.lineJoin = 'round'
+  canvasTxt.value.stroke()
+  canvasTxt.value.closePath()
+  points.value.push(obj)
+  points.value.push({ x: -1, y: -1 })
+}
+// 生成
+const generate = (options) => {
+  let imgFormat = options && options.format ? options.format : props.format
+  let imgQuality = options && options.quality ? options.quality : props.quality
+  const pm = new Promise((resolve, reject) => {
+    if (!hasDrew.value) {
+      reject(`Warning: Not Signned!`)
+      return
+    }
+    let resImgData = canvasTxt.value.getImageData(
+      0,
+      0,
+      canvasRef.value.width,
+      canvasRef.value.height
+    )
+    canvasTxt.value.globalCompositeOperation = 'destination-over'
+    canvasTxt.value.fillStyle = bgColor.value
+    canvasTxt.value.fillRect(0, 0, canvasRef.value.width, canvasRef.value.height)
+    resultImg.value = canvasRef.value.toDataURL(imgFormat, imgQuality)
+    canvasTxt.value.clearRect(0, 0, canvasRef.value.width, canvasRef.value.height)
+    canvasTxt.value.putImageData(resImgData, 0, 0)
+    canvasTxt.value.globalCompositeOperation = 'source-over'
+    if (props.isCrop) {
+      const crop_area = getCropArea(resImgData.data)
+      let crop_canvas = document.createElement('canvas')
+      const crop_ctx = crop_canvas.getContext('2d')
+      crop_canvas.width = crop_area[2] - crop_area[0]
+      crop_canvas.height = crop_area[3] - crop_area[1]
+      const crop_imgData = canvasTxt.value.getImageData(...crop_area)
+      crop_ctx.globalCompositeOperation = 'destination-over'
+      crop_ctx.putImageData(crop_imgData, 0, 0)
+      crop_ctx.fillStyle = bgColor.value
+      crop_ctx.fillRect(0, 0, crop_canvas.width, crop_canvas.height)
+      resultImg.value = crop_canvas.toDataURL(imgFormat, imgQuality)
+    }
+    resolve(resultImg.value)
+  })
+  return pm
+}
+const reset = () => {
+  canvasTxt.value.clearRect(0, 0, canvasRef.value.width, canvasRef.value.height)
+  if (props.isClearBgColor) {
+    emits('update:bgColor', '')
+    canvasRef.value.style.background = 'rgba(255, 255, 255, 0)'
+  }
+  points.value = []
+  hasDrew.value = false
+  resultImg.value = ''
+}
+const getCropArea = (imgData) => {
+  let topX = canvasRef.value.width
+  let btmX = 0
+  let topY = canvasRef.value.height
+  let btnY = 0
+  for (let i = 0; i < canvasRef.value.width; i++) {
+    for (let j = 0; j < canvasRef.value.height; j++) {
+      let pos = (i + canvasRef.value.width * j) * 4
+      if (imgData[pos] > 0 || imgData[pos + 1] > 0 || imgData[pos + 2] || imgData[pos + 3] > 0) {
+        btnY = Math.max(j, btnY)
+        btmX = Math.max(i, btmX)
+        topY = Math.min(j, topY)
+        topX = Math.min(i, topX)
+      }
+    }
+  }
+  topX++
+  btmX++
+  topY++
+  btnY++
+  const data = [topX, topY, btmX, btnY]
+  return data
+}
+
+defineExpose({
+  generate
+})
+onBeforeMount(() => {
+  window.addEventListener('resize', resizeHandler)
+})
+onBeforeUnmount(() => {
+  window.removeEventListener('resize', resizeHandler)
+})
+onMounted(() => {
+  canvasRef.value.height = props.height
+  canvasRef.value.width = props.width
+  canvasRef.value.style.background = bgColor.value
+  resizeHandler()
+  // 在画板以外松开鼠标后冻结画笔
+  document.onmouseup = () => {
+    isDrawing.value = false
+  }
+})
+</script>