cdt-cli/cdt-vue/src/utils/watermark.js

A simple CLI for creating your projects

'use strict'

let watermark = {}

let setWatermark = (str) => {
  let id = '1.23452384164.123412415'

  if (document.getElementById(id) !== null) {
    document.body.removeChild(document.getElementById(id))
  }

  let can = document.createElement('canvas')
  can.width = 300
  can.height = 80
  CanvasRenderingContext2D.prototype.wrapText = function (text, x, y, maxWidth, lineHeight) {
    if (typeof text != 'string' || typeof x != 'number' || typeof y != 'number') {
        return;
    }

    var context = this;
    var canvas = context.canvas;

    if (typeof maxWidth == 'undefined') {
        maxWidth = (canvas && canvas.width) || 400;
    }
    if (typeof lineHeight == 'undefined') {
        lineHeight = (canvas && parseInt(window.getComputedStyle(canvas).lineHeight)) || parseInt(window.getComputedStyle(document.body).lineHeight);
    }

    // 字符分隔为数组
    var arrText = text.split('');
    var line = '';

    for (var n = 0; n < arrText.length; n++) {
        var testLine = line + arrText[n];
        var metrics = context.measureText(testLine);
        var testWidth = metrics.width;
        if (testWidth > maxWidth && n > 0) {
            context.fillText(line, x, y);
            line = arrText[n];
            y += lineHeight;
        } else {
            line = testLine;
        }
    }
    context.fillText(line, x, y);
};
  let cans = can.getContext('2d')
   cans.rotate(-5 * Math.PI / 180)
  cans.font = '20px Vedana'
  cans.fillStyle = 'rgba(200, 200, 200, 0.30)'
  cans.textAlign = 'left'
  cans.textBaseline = 'Middle'
  cans.wrapText(str, 0, 40,300,40)
  cans.save()

  let div = document.createElement('div')
  div.id = id
  div.style.pointerEvents = 'none'
  div.style.top = '70px'
  div.style.left = '0px'
  div.style.position = 'fixed'
  div.style.zIndex = '22'
  div.style.width = document.documentElement.clientWidth  + 'px'
  div.style.height = document.documentElement.clientHeight  + 'px'
  div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat'
  document.body.appendChild(div)
  return id
}

// 该方法只允许调用一次
watermark.set = (str) => {
  setWatermark(str)
}

export default watermark