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