/**
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* CSignatureLayer - 签名层
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* @author Tevin
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*/
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<template>
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<AtFloatLayout
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class="c-signature-layer"
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title="手写板 / 请书写签名"
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:isOpened="layerOpened"
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:onClose="evt => handleClose()"
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>
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<view class="c-signature-layer-draw">
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<view class="size-box-top"></view>
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<view class="size-box-bottom"></view>
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<canvas
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class="drawing"
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ref="drawing"
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:canvasId="cavId"
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:width="cavWidth"
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:height="cavHeight"
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:disableScroll="true"
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@touchstart="evt => handleWriteStart(evt)"
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@touchmove="evt => handleWriteMove(evt)"
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@touchend="evt => handleWriteEnd(evt)"
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></canvas>
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</view>
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<view class="c-signature-layer-btns">
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<AtButton
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class="btn-warning"
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type="primary"
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size="large"
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:onClick="evt => handleRestDraw()"
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>重写</AtButton>
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<AtButton
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type="primary"
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size="large"
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:onClick="evt => handleSaveDraw()"
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>完成</AtButton>
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</view>
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</AtFloatLayout>
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</template>
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<script>
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import Taro from '@tarojs/taro';
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import { $ } from '@tarojs/extend';
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import { AtFloatLayout, AtButton } from 'taro-ui-vue';
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import './cSignatureLayer.scss';
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import { Tools } from '@components/common/Tools';
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export default {
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name: 'CSignatureLayer',
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components: {
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AtFloatLayout,
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AtButton,
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},
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props: {},
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data() {
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return {
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cavId: 'signCanvas-' + Date.now() + '-' + parseInt(Math.random() * 10000),
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layerOpened: false,
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cavWidth: 0,
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cavHeight: 0,
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curPoint: {},
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lastPoint: {},
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curLine: [],
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// 第一次触发
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firstTouch: true,
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// 所有笔迹
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chirography: [],
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// 初始画圆的半径
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radius: 1,
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};
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},
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methods: {
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_initDraw() {
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this.canvasContext = Taro.createCanvasContext(this.cavId, this);
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const $container = $(this.$refs.drawing).parent();
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setTimeout(() => {
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$container.width().then(w => (this.cavWidth = w));
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$container.height().then(h => (this.cavHeight = h));
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}, 0);
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},
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$onDraw(callback) {
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this._initDraw();
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this.layerOpened = true;
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this._callback = callback;
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setTimeout(() => {
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this.handleRestDraw();
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}, 10);
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},
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handleRestDraw() {
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this.firstTouch = true;
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this.curLine = [];
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this.chirography = [];
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this.canvasContext.clearRect(0, 0, this.cavWidth, this.cavHeight);
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this.canvasContext.draw();
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},
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handleClose() {
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this.layerOpened = false;
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},
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handleWriteStart(evt) {
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if (evt.type != 'touchstart') {
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return false;
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}
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this.canvasContext.setFillStyle('#1A1A1A');
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const point = {
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x: evt.touches[0].x,
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y: evt.touches[0].y,
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};
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this.curLine.unshift({
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time: Date.now(),
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dis: 0,
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x: point.x,
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y: point.y,
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});
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if (this.firstTouch) {
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this.cutArea = {
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top: point.y,
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right: point.x,
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bottom: point.y,
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left: point.x,
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};
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this.firstTouch = false;
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}
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this._pointToLine(this.curLine);
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},
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handleWriteMove(evt) {
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if (evt.type != 'touchmove') {
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return false;
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}
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if (evt.cancelable) {
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// 判断默认行为是否已经被禁用
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if (!evt.defaultPrevented) {
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evt.preventDefault();
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}
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}
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const point = {
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x: evt.touches[0].x,
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y: evt.touches[0].y,
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};
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this._updateCutArea(point);
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this.lastPoint = this.curPoint;
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this.curPoint = point;
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this.curLine.unshift({
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time: Date.now(),
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dis: this._distance(point, this.lastPoint),
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x: point.x,
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y: point.y,
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});
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this._pointToLine(this.curLine);
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},
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handleWriteEnd(evt) {
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if (evt.type != 'touchend') {
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return 0;
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}
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const point = {
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x: evt.changedTouches[0].x,
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y: evt.changedTouches[0].y,
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};
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this.lastPoint = this.curPoint;
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this.curPoint = point;
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this.curLine.unshift({
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time: Date.now(),
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dis: this._distance(point, this.lastPoint),
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x: point.x,
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y: point.y,
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});
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this._pointToLine(this.curLine);
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this.chirography.unshift(this.curLine);
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this.curLine = [];
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},
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// 更新裁剪区域
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_updateCutArea(point) {
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if (point.y < this.cutArea.top) {
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this.cutArea.top = point.y;
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}
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if (point.y < 0) {
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this.cutArea.top = 0;
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}
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if (point.x > this.cutArea.right) {
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this.cutArea.right = point.x;
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}
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if (this.cavWidth - point.x <= 0) {
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this.cutArea.right = this.cavWidth;
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}
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if (point.y > this.cutArea.bottom) {
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this.cutArea.bottom = point.y;
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}
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if (this.cavHeight - point.y <= 0) {
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this.cutArea.bottom = this.cavHeight;
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}
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if (point.x < this.cutArea.left) {
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this.cutArea.left = point.x;
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}
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if (point.x < 0) {
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this.cutArea.left = 0;
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}
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},
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// 求两点之间距离
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_distance(a, b) {
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let x = b.x - a.x;
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let y = b.y - a.y;
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return Math.sqrt(x * x + y * y);
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},
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// 绘制笔迹
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_pointToLine(line) {
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this._calcBethelLine(line);
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},
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// 计算插值的方式
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_calcBethelLine(line) {
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if (line.length <= 1) {
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line[0].r = this.radius;
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return;
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}
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// 笔迹倍数
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const lineSize = 1.5;
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// 最小笔画半径
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const lineMin = 0.5;
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// 最大笔画半径
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const lineMax = 4;
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// 默认压力
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const pressure = 1;
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// 顺滑度，用60的距离来计算速度
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const smoothness = 60;
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// 开始计算
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let x0,
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x1,
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x2,
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y0,
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y1,
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y2,
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r0,
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r1,
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r2,
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len,
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lastRadius,
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dis = 0,
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time = 0,
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curveValue = 0.5;
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if (line.length <= 2) {
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x0 = line[1].x;
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y0 = line[1].y;
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x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
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y2 = line[1].y + (line[0].y - line[1].y) * curveValue;
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//x2 = line[1].x;
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//y2 = line[1].y;
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x1 = x0 + (x2 - x0) * curveValue;
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y1 = y0 + (y2 - y0) * curveValue;
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} else {
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x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
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y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
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x1 = line[1].x;
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y1 = line[1].y;
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x2 = x1 + (line[0].x - x1) * curveValue;
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y2 = y1 + (line[0].y - y1) * curveValue;
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}
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// 从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上
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len = this._distance({ x: x2, y: y2 }, { x: x0, y: y0 });
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lastRadius = this.radius;
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for (let n = 0; n < line.length - 1; n++) {
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dis += line[n].dis;
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time += line[n].time - line[n + 1].time;
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if (dis > smoothness) {
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break;
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}
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}
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this.radius = Math.min((time / len) * pressure + lineMin, lineMax) * lineSize;
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line[0].r = this.radius;
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//计算笔迹半径；
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if (line.length <= 2) {
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r0 = (lastRadius + this.radius) / 2;
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r1 = r0;
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r2 = r1;
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//return;
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} else {
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r0 = (line[2].r + line[1].r) / 2;
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r1 = line[1].r;
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r2 = (line[1].r + line[0].r) / 2;
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}
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let n = 5;
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let point = [];
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for (let i = 0; i < n; i++) {
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let t = i / (n - 1);
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let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
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let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
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let r = lastRadius + ((this.radius - lastRadius) / n) * i;
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point.push({ x: x, y: y, r: r });
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if (point.length == 3) {
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let a = this._ctaCalc(
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point[0].x,
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point[0].y,
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point[0].r,
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point[1].x,
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point[1].y,
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point[1].r,
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point[2].x,
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point[2].y,
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point[2].r,
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);
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this._bethelDraw(a, true);
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point = [{ x: x, y: y, r: r }];
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}
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}
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this.curLine = line;
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},
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_ctaCalc(x0, y0, r0, x1, y1, r1, x2, y2, r2) {
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let a = [],
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vx01,
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vy01,
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norm,
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n_x0,
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n_y0,
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vx21,
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vy21,
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n_x2,
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n_y2;
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vx01 = x1 - x0;
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vy01 = y1 - y0;
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norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
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vx01 = (vx01 / norm) * r0;
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vy01 = (vy01 / norm) * r0;
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n_x0 = vy01;
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n_y0 = -vx01;
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vx21 = x1 - x2;
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vy21 = y1 - y2;
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norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
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vx21 = (vx21 / norm) * r2;
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vy21 = (vy21 / norm) * r2;
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n_x2 = -vy21;
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n_y2 = vx21;
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a.push({ mx: x0 + n_x0, my: y0 + n_y0, color: '#1A1A1A' });
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a.push({
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c1x: x1 + n_x0,
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c1y: y1 + n_y0,
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c2x: x1 + n_x2,
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c2y: y1 + n_y2,
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ex: x2 + n_x2,
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ey: y2 + n_y2,
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});
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a.push({
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c1x: x2 + n_x2 - vx21,
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c1y: y2 + n_y2 - vy21,
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c2x: x2 - n_x2 - vx21,
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c2y: y2 - n_y2 - vy21,
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ex: x2 - n_x2,
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ey: y2 - n_y2,
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});
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a.push({
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c1x: x1 - n_x2,
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c1y: y1 - n_y2,
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c2x: x1 - n_x0,
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c2y: y1 - n_y0,
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ex: x0 - n_x0,
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ey: y0 - n_y0,
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});
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a.push({
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c1x: x0 - n_x0 - vx01,
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c1y: y0 - n_y0 - vy01,
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c2x: x0 + n_x0 - vx01,
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c2y: y0 + n_y0 - vy01,
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ex: x0 + n_x0,
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ey: y0 + n_y0,
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});
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a[0].mx = a[0].mx.toFixed(1);
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a[0].mx = parseFloat(a[0].mx);
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a[0].my = a[0].my.toFixed(1);
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a[0].my = parseFloat(a[0].my);
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for (let i = 1; i < a.length; i++) {
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a[i].c1x = a[i].c1x.toFixed(1);
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a[i].c1x = parseFloat(a[i].c1x);
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a[i].c1y = a[i].c1y.toFixed(1);
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a[i].c1y = parseFloat(a[i].c1y);
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a[i].c2x = a[i].c2x.toFixed(1);
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a[i].c2x = parseFloat(a[i].c2x);
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a[i].c2y = a[i].c2y.toFixed(1);
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a[i].c2y = parseFloat(a[i].c2y);
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a[i].ex = a[i].ex.toFixed(1);
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a[i].ex = parseFloat(a[i].ex);
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a[i].ey = a[i].ey.toFixed(1);
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a[i].ey = parseFloat(a[i].ey);
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}
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return a;
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},
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_bethelDraw(point, isFill) {
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const ctx = this.canvasContext;
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ctx.beginPath();
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ctx.moveTo(point[0].mx, point[0].my);
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for (let i = 1; i < point.length; i++) {
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ctx.bezierCurveTo(
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point[i].c1x,
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point[i].c1y,
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point[i].c2x,
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point[i].c2y,
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point[i].ex,
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point[i].ey,
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);
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}
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ctx.stroke();
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if (isFill !== undefined) {
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// 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序
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ctx.fill();
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}
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ctx.draw(true);
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},
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_brushingGround(callback) {
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Taro.canvasToTempFilePath({
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canvasId: this.cavId,
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x: 0,
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y: 0,
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width: Math.ceil(this.cavWidth),
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height: Math.ceil(this.cavHeight),
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destWidth: Math.ceil(this.cavWidth),
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destHeight: Math.ceil(this.cavHeight),
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quality: 1,
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fileType: 'png',
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success: res => {
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const ctx = this.canvasContext;
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ctx.setFillStyle('#ffffff');
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ctx.fillRect(0, 0, this.cavWidth, this.cavHeight);
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ctx.drawImage(res.tempFilePath, 0, 0);
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ctx.draw(false, () => {
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callback();
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});
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},
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});
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},
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handleSaveDraw() {
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if (this.firstTouch) {
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Tools.toast('请书写签名！');
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}
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this._brushingGround(() => {
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const delta = 20;
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const clipArea = { x: 0, y: 0, w: 0, h: 0 };
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clipArea.x = Math.max(this.cutArea.left - delta, 0);
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clipArea.y = Math.max(this.cutArea.top - delta, 0);
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const realRight = Math.min(this.cutArea.right + delta, this.cavWidth);
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const realBottom = Math.min(this.cutArea.bottom + delta, this.cavHeight);
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clipArea.w = realRight - clipArea.x;
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clipArea.h = realBottom - clipArea.y;
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Taro.canvasToTempFilePath({
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canvasId: this.cavId,
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x: clipArea.x,
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y: clipArea.y,
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width: clipArea.w,
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height: clipArea.h,
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destWidth: clipArea.w,
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destHeight: clipArea.h,
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quality: 0.6,
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fileType: 'jpeg',
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success: res => {
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this._callback(res.tempFilePath);
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this.layerOpened = false;
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},
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});
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});
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},
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},
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mounted() {
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this.$nextTick(() => {
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this._initDraw();
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});
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},
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};
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</script>
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