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+<template>
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+ <view class="signature-wrap">
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+ <canvas
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+ ref="canvas"
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+ :canvas-id="cid"
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+ :id="cid"
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+ @touchstart="onTouchStart"
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+ @touchmove="onTouchMove"
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+ @touchend="onTouchEnd"
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+ disable-scroll
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+ :style="[
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+ {
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+ width: width && formatSize(width),
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+ height: height && formatSize(height)
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+ },
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+ customStyle
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+ ]"
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+ ></canvas>
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+ <slot />
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+ </view>
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+</template>
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+
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+<script>
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+ /**
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+ * sign canvas 手写签名
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+ * @description 设置线条宽度、颜色,撤回,清空
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+ * @tutorial
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+ * @property {String} cid canvas id 不设置则默认为 v-sign-时间戳
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+ * @property {String, Number} width canvas 宽度
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+ * @property {String, Number} height canvas 高度
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+ * @property {bgColor} bgColor 画布背景颜色
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+ * @property {Object} customStyle canvas 自定义样式
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+ * @property {String} lineWidth 画笔大小,权重小于 v-sign-pen 组件设置的画笔大小
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+ * @property {Number} lineColor 画笔颜色,权重小于 v-sign-pen 组件设置的画笔大小
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+ * @event {Function} init 当创建完 canvas 实例后触发,向外提供 canvas实例,撤回,清空方法
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+ * @example <v-sign @init="signInit"></v-sign>
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+ */
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+ import { formatSize } from '@/utils/utils'
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+
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+ export default {
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+ name: 'my-sign',
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+ props: {
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+ // canvas id
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+ cid: {
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+ type: String,
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+ default: `v-sign-${Date.now()}`
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+ // required: true
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+ },
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+ // canvas 宽度
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+ width: {
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+ type: [String, Number]
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+ },
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+ // canvas 高度
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+ height: {
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+ type: [String, Number]
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+ },
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+ // 画笔大小,权重小于 v-sign-pen 组件设置的画笔大小 penLineWidth
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+ lineWidth: {
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+ type: Number,
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+ default: 4
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+ },
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+ // 线颜色,权重小于 v-sign-color 组件设置的画笔颜色 penLineColor
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+ lineColor: {
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+ type: String,
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+ default: '#333'
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+ },
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+ // 画布背景颜色
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+ bgColor: {
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+ type: String,
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+ default: '#fff'
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+ },
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+ // canvas自定义样式
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+ customStyle: {
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+ type: Object,
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+ default: () => ({})
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+ }
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+ },
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+ provide() {
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+ return {
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+ getSignInterface: this.provideSignInterface
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+ }
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+ },
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+ data() {
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+ return {
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+ formatSize,
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+ lineData: [],
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+ winWidth: 0,
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+ winHeight: 0,
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+ penLineWidth: null, // v-sign-pen 组件设置的画笔大小
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+ penLineColor: null // v-sign-color 组件设置的颜色
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+ }
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+ },
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+ created() {
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+ // 获取窗口宽高
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+ const { windowWidth, windowHeight } = uni.getSystemInfoSync()
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+ this.winWidth = windowWidth
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+ this.winHeight = windowHeight
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+ },
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+ mounted() {
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+ this.canvasCtx = uni.createCanvasContext(this.cid, this)
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+ // h5 需延迟绘制,否则绘制失败
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+ // #ifdef H5
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+ setTimeout(() => {
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+ // #endif
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+ this.setBackgroundColor(this.bgColor)
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+ // #ifdef H5
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+ }, 10)
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+ // #endif
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+ // 初始化完成,触发 init 事件
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+ this.$emit('init', this.provideSignInterface())
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+ },
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+ methods: {
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+ onTouchStart(e) {
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+ const pos = e.touches[0]
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+ this.lineData.push({
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+ style: {
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+ color: this.penLineColor || this.lineColor,
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+ width: this.penLineWidth || this.lineWidth
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+ },
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+ // 屏幕坐标
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+ coordinates: [
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+ {
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+ type: e.type,
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+ x: pos.x,
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+ y: pos.y
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+ }
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+ ]
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+ })
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+ this.drawLine()
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+ },
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+ onTouchMove(e) {
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+ const pos = e.touches[0]
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+ this.lineData[this.lineData.length - 1].coordinates.push({
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+ type: e.type,
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+ x: pos.x,
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+ y: pos.y
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+ })
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+ this.drawLine()
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+ },
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+ onTouchEnd(e) {
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+ this.$emit('end', this.lineData)
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+ },
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+ // 清空画布
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+ clear() {
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+ this.lineData = []
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+ this.canvasCtx.clearRect(0, 0, this.winWidth, this.winHeight)
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+ this.canvasCtx.draw()
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+ this.setBackgroundColor(this.bgColor)
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+ this.$emit('clear')
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+ },
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+ // 撤销
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+ revoke() {
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+ this.setBackgroundColor(this.bgColor)
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+ this.lineData.pop()
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+ this.lineData.forEach((item, index) => {
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+ this.canvasCtx.beginPath()
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+ this.canvasCtx.setLineCap('round')
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+ this.canvasCtx.setStrokeStyle(item.style.color)
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+ this.canvasCtx.setLineWidth(item.style.width)
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+ if (item.coordinates.length < 2) {
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+ const pos = item.coordinates[0]
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+ this.canvasCtx.moveTo(pos.x, pos.y)
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+ this.canvasCtx.lineTo(pos.x + 1, pos.y)
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+ } else {
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+ item.coordinates.forEach((pos) => {
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+ if (pos.type == 'touchstart') {
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+ this.canvasCtx.moveTo(pos.x, pos.y)
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+ } else {
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+ this.canvasCtx.lineTo(pos.x, pos.y)
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+ }
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+ })
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+ }
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+ this.canvasCtx.stroke()
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+ })
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+ this.canvasCtx.draw(true)
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+ this.$emit('revoke', this.lineData)
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+ },
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+ // 绘制线条
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+ drawLine() {
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+ const lineDataLen = this.lineData.length
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+ if (!lineDataLen) return
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+ const currentLineData = this.lineData[lineDataLen - 1]
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+ const coordinates = currentLineData.coordinates
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+ const coordinatesLen = coordinates.length
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+ if (!coordinatesLen) return
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+ let startPos
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+ let endPos
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+ if (coordinatesLen < 2) {
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+ // only start, no move event
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+ startPos = coordinates[coordinatesLen - 1]
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+ endPos = {
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+ x: startPos.x + 1,
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+ y: startPos.y
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+ }
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+ } else {
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+ startPos = coordinates[coordinatesLen - 2]
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+ endPos = coordinates[coordinatesLen - 1]
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+ }
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+
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+ const style = currentLineData.style
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+ this.canvasCtx.beginPath()
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+ this.canvasCtx.setLineCap('round')
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+ this.canvasCtx.setStrokeStyle(style.color)
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+ this.canvasCtx.setLineWidth(style.width)
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+ this.canvasCtx.moveTo(startPos.x, startPos.y)
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+ this.canvasCtx.lineTo(endPos.x, endPos.y)
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+ // const P1 = this.caculateBezier(startPos, endPos, centerPos)
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+ // console.log(P1.x, P1.y)
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+ // this.canvasCtx.moveTo(startPos.x, startPos.y)
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+ // this.canvasCtx.quadraticCurveTo(P1.x, P1.y, endPos.x, endPos.y)
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+ this.canvasCtx.stroke()
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+ this.canvasCtx.draw(true)
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+ },
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+ // 保存png图片,文件名配置 filename 仅支持 h5
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+ async saveImage(filename = '签名') {
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+ const tempFilePath = await this.canvasToTempFilePath()
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+ return new Promise((resolve, reject) => {
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+ // #ifdef H5
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+ try {
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+ const a = document.createElement('a')
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+ a.href = tempFilePath
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+ a.download = filename
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+ document.body.appendChild(a)
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+ a.click()
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+ a.remove()
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+ resolve({
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+ errMsg: 'saveImageH5:ok'
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+ })
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+ } catch (e) {
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+ console.error(e)
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+ reject(e)
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+ }
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+ // #endif
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+ // #ifndef H5
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+ uni.saveImageToPhotosAlbum({
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+ filePath: tempFilePath,
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+ success(resObj) {
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+ resolve(resObj)
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+ },
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+ fail(err) {
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+ reject(err)
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+ }
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+ })
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+ // #endif
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+ })
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+ },
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+ // canvas 保存为临时图片路径,h5返回 base64
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+ canvasToTempFilePath(conf = {}) {
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+ return new Promise((resolve, reject) => {
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+ uni.canvasToTempFilePath(
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+ {
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+ canvasId: this.cid,
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+ ...conf,
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+ success: (res) => {
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+ resolve(res.tempFilePath)
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+ },
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+ fail: (err) => {
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+ console.log('fail', err)
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+ reject(err)
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+ }
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+ },
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+ this
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+ )
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+ })
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+ },
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+ setBackgroundColor(color = '#fff') {
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+ this.canvasCtx.beginPath()
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+ this.canvasCtx.setFillStyle(color)
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+ this.canvasCtx.fillRect(0, 0, this.winWidth, this.winHeight)
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+ this.canvasCtx.fill()
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+ this.canvasCtx.draw(true)
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+ },
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+ setLineWidth(numberVal) {
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+ this.penLineWidth = numberVal
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+ },
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+ setLineColor(strValue) {
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+ this.penLineColor = strValue
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+ },
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+ // 向外暴露内部方法
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+ provideSignInterface() {
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+ return {
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+ cid: this.cid,
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+ ctx: this.canvasCtx,
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+ clear: this.clear,
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+ revoke: this.revoke,
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+ saveImage: this.saveImage,
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+ canvasToTempFilePath: this.canvasToTempFilePath,
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+ setLineWidth: this.setLineWidth,
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+ setLineColor: this.setLineColor,
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+ setBackgroundColor: this.setBackgroundColor,
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+ getLineData: () => this.lineData,
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+ canvas2base64: this.canvas2base64
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+ }
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+ },
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+ /**
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+ * 计算二次贝塞尔曲线 控制点 P1
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+ * 起点 P0(x0,y0)、控制点P1(x1, y1)、P2(x2, y2)、曲线上任意点B(x, y)
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+ * 二次贝塞尔公式:B(t) = (1-t)²P0 + 2t(1-t)P1 + t²P2
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+ * 代入坐标得:
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+ * x = (1-t)²*x0 + 2t(1-t)*x1 + t²*x2
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+ * y = (1-t)²*y0 + 2t(1-t)*y1 + t²*y2
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+ */
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+ caculateBezier(P0, P2, B, t = 0.5) {
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+ const { x: x0, y: y0 } = P0
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+ const { x: x2, y: y2 } = P2
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+ const { x, y } = B
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+ let x1 = (x - (1 - t) * (1 - t) * x0 - t * t * x2) / (2 * t * (1 - t))
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+ let y1 = (y - (1 - t) * (1 - t) * y0 - t * t * y2) / (2 * t * (1 - t))
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+ return {
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+ x: x1,
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+ y: y1
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+ }
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+ },
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+ canvas2base64() {
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+ // 保存签名图片
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+ const dataURL = this.$refs.canvas.toDataURL('image/png')
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+ console.log(dataURL)
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+ }
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+ }
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+ }
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+</script>
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+
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+<style lang="scss" scoped>
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+ .signature-wrap {
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+ position: relative;
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+ }
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+</style>
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