@zhangyida_1990/watermark

Introduction

Watermark is a simple and quick library to draw watermark on HTML element.

new Watermark().set({
  // some options
}).mount('body').draw().destory();

new Watermark('body', {
  textArray: ['Hello, world!'],
  rotate: Math.PI / 6,
  color: #aaa
}).draw();

Get Started

Installatin

yarn add @zhangyida_1990/watermark

API

constructor([el][, options])

• Arguments:

    el {String | HTMLElement}['']       selector or html element
    options {Object} [{...}]             options for watermark
      textArray {Array} [['example']]   text list to display`
      fontSize {Number} [26]            font size`
      fontFamily {String} ['serif']     font family`
      padding {Number} [25]             watermark wrapper padding with text`
      lineHeight {Number} [-1]          text line height`
      rotate {Number} [0]               the angle of rotate, must in range of (-PI/2, PI/2)
      fontScale {Number} [0.5]          Half-width and full-width fonts width ratio
      color {String} ['#eeeeee']        text color
      auto {Boolean} [true]             whether add background to mounted element automatically
      observe {Boolean} [true]          whether observe background of mounted element
      openInvisibleWatermark { Boolean } [false] open invisible watermark
  

• Example:

  • new Watermark();

  • new Watermark('body', {
      textArray: [
        'example',
        '你好，欢迎使用',
        'Hello, 世界'
      ],
      fontSize: 16,
    });

• Note: If you set options.auto = false, Watermark will never add background to the mounted element, you must do it manually. for example:

    /*
     * use api
     */
    const watermark = new Watermark('body', { auto: false });
    // ... do some action
    watermark.draw();
    // you can access canvas by watermark.canvas properity
    watermark.render();   // must after draw call

    /*
     * use pure js
     */
    const watermark = new Watermark('body', {
      auto: false,
    });
    watermark.draw();
    const canvas = watermark.draw().canvas;
    const dataUrl = canvas.toDataURL();
    const body = document.body;
    body.style.background = `url(${dataUrl})`;

mount(el)

• Arguments:

  • el {String | HTMLElement} selector or html element

• Usage:

  If a watermark instance not mount any element when is was created, you can use mount function to mount a element for it.

• Example:

  • const watermark = new Watermark({
      color: '#cccccc'
    }); // create a instance of Watermark
    watermark.mount('body');  // mount to document.body
    // watermark.draw();  // dont fotget to use draw() to display watermark on mounted element

set(options)

• Arguments:

  • options {Object}[{...}] options for watermark

• Usage:

  It's default value is same as constructor You can use set function to re-configurate watermark style

• Example:

  •   const watermark = new Watermark('body', {
        // your options
      });
      // if you want to re-configurate
      watermark.set({
        // your new options
      });
      // watermark.draw();  must use draw() to display

draw()

• Usage:

  use this function to render watermark on the mounted element.

• Example:

  • new Watermark('body').draw();

  • new Watermark().set().mount().draw();

  • new Watermark('body').set().draw();

destory()

• Usage:

  • unmount element
  • disconnect mutation observer
  • change options to default value

• Example:

  • new Watermark().set().mount().destory();

render()

• Usage:

  • add background to mounted element

• Note:

  • only used in situation that options.auto is setted to false

observer()

• Usage:

  • add observer that can observe background of mounted element

• Note:

  • only used in situation that options.observe is setted to false

Contributors

If you are interested in this project, welcome to fork and pull request.

License

MIT License

Copyright (c) 2018-present, tyx1703