antd-mobile-taro-ui/es/components/water-mark/water-mark.js

以antd-mobile为设计标准，基于taro框架的微信小程序组件库

import classNames from 'classnames';
import React, { useEffect, useRef, useState } from 'react';
import { withNativeProps } from 'antd-mobile/es/utils/native-props';
import { mergeProps } from 'antd-mobile/es/utils/with-default-props';
import { View, Canvas } from '@tarojs/components';
import Taro from '@tarojs/taro';
import { isH5, isWeapp } from '../../utils/client';
const classPrefix = `adm-water-mark`;
const defaultProps = {
  fullPage: true
};
export const WaterMark = p => {
  const props = mergeProps(defaultProps, p);
  const {
    zIndex = 2000,
    gapX = 24,
    gapY = 48,
    width = 120,
    height = 64,
    rotate = -22,
    image,
    imageWidth = 120,
    imageHeight = 64,
    content,
    fontStyle = 'normal',
    fontWeight = 'normal',
    fontColor = 'rgba(0,0,0,.15)',
    fontSize = 14,
    fontFamily = 'sans-serif'
  } = props;
  const [base64Url, setBase64Url] = useState('');
  const canvasRef = useRef(null);
  useEffect(() => {
    setTimeout(() => {
      var _a, _b;

      const canvasDraw = (canvas, ratio, img) => {
        const ctx = canvas.getContext('2d');
        const canvasWidth = (gapX + width) * ratio;
        const canvasHeight = (gapY + height) * ratio;
        const markWidth = width * ratio;
        const markHeight = height * ratio;
        canvas.width = canvasWidth;
        canvas.height = canvasHeight;

        if (ctx) {
          if (image) {
            ctx.translate(markWidth / 2, markHeight / 2);
            ctx.rotate(Math.PI / 180 * Number(rotate));
            img.crossOrigin = 'anonymous';
            img.referrerPolicy = 'no-referrer';

            img.onload = () => {
              ctx.drawImage(img, -imageWidth * ratio / 2, -imageHeight * ratio / 2, imageWidth * ratio, imageHeight * ratio);
              ctx.restore();
              setBase64Url(canvas.toDataURL());
            };

            img.src = image;
          } else if (content) {
            ctx.textBaseline = 'middle';
            ctx.textAlign = 'center';
            ctx.translate(markWidth / 2, markHeight / 2);
            ctx.rotate(Math.PI / 180 * Number(rotate));
            const markSize = Number(fontSize) * ratio;
            ctx.font = `${fontStyle} normal ${fontWeight} ${markSize}px/${markHeight}px ${fontFamily}`;
            ctx.fillStyle = fontColor;
            ctx.fillText(content, 0, 0);
            ctx.restore();
            setBase64Url(canvas.toDataURL());
          }
        } else {
          throw new Error('Canvas is not supported in the current environment');
        }
      };

      if (isWeapp) {
        const query = Taro.createSelectorQuery();
        if (!canvasRef.current) return;

        if ((_a = canvasRef.current) === null || _a === void 0 ? void 0 : _a.sid) {
          query.select(`#${(_b = canvasRef.current) === null || _b === void 0 ? void 0 : _b.sid}`).fields({
            node: true,
            size: true
          }).exec(res => {
            var _a, _b;

            const canvas = (_a = res[0]) === null || _a === void 0 ? void 0 : _a.node;
            const ratio = ((_b = Taro.getSystemInfoSync()) === null || _b === void 0 ? void 0 : _b.pixelRatio) || 1;
            const img = canvas.createImage();
            canvasDraw(canvas, ratio, img);
          });
        }
      } else if (isH5) {
        const canvas = document.createElement('canvas');
        const ratio = window.devicePixelRatio;
        const img = new Image();
        canvasDraw(canvas, ratio, img);
      }
    }, 0);
  }, [gapX, gapY, rotate, fontStyle, fontWeight, width, height, fontFamily, fontColor, image, content, fontSize]);
  return withNativeProps(props, React.createElement(React.Fragment, null, React.createElement(View, {
    className: classNames(classPrefix, {
      [`${classPrefix}-full-page`]: props.fullPage
    }),
    style: {
      zIndex,
      backgroundSize: `${gapX + width}px`,
      backgroundImage: `url('${base64Url}')`
    }
  }), React.createElement(Canvas, {
    type: '2d',
    style: {
      display: 'none'
    },
    ref: canvasRef
  })));
};