flutter_widget_from_html_core

Flutter package to render html as widgets that focuses on correctness and extensibility. Supports 70+ most popular tags.

Live demo

Getting Started

Add this to your app's pubspec.yaml file:

dependencies:
  flutter_widget_from_html_core: ^0.15.2

Usage

Then you have to import the package with:

import 'package:flutter_widget_from_html_core/flutter_widget_from_html_core.dart';

And use HtmlWidget where appropriate:

HtmlWidget(
  // the first parameter (`html`) is required
  '''
  <h3>Heading</h3>
  <p>
    A paragraph with <strong>strong</strong>, <em>emphasized</em>
    and <span style="color: red">colored</span> text.
  </p>
  ''',

  // all other parameters are optional, a few notable params:

  // specify custom styling for an element
  // see supported inline styling below
  customStylesBuilder: (element) {
    if (element.classes.contains('foo')) {
      return {'color': 'red'};
    }

    return null;
  },

  customWidgetBuilder: (element) {
    if (element.attributes['foo'] == 'bar') {
      // render a custom widget that takes the full width
      return FooBarWidget();
    }

    if (element.attributes['fizz'] == 'buzz') {
      // render a custom widget that inlines with surrounding text
      return InlineCustomWidget(
        child: FizzBuzzWidget(),
      )
    }

    return null;
  },

  // this callback will be triggered when user taps a link
  onTapUrl: (url) => print('tapped $url'),

  // select the render mode for HTML body
  // by default, a simple `Column` is rendered
  // consider using `ListView` or `SliverList` for better performance
  renderMode: RenderMode.column,

  // set the default styling for text
  textStyle: TextStyle(fontSize: 14),
),

Features

HTML tags

Below tags are the ones that have special meaning / styling, all other tags will be parsed as text. Compare between Flutter rendering and browser's.

A: underline, theme accent color with scroll to anchor support
H1/H2/H3/H4/H5/H6
IMG with support for asset (asset://), data uri, local file (file://) and network image
LI/OL/UL with support for:
- Attributes: type, start, reversed
- Inline style list-style-type values: lower-alpha, upper-alpha, lower-latin, upper-latin, circle, decimal, disc, lower-roman, upper-roman, square
TABLE/CAPTION/THEAD/TBODY/TFOOT/TR/TD/TH with support for:
- TABLE attributes border, cellpadding, cellspacing
- TD/TH attributes colspan, rowspan, valign
- Table is scrollable if columns are too wide
ABBR, ACRONYM, ADDRESS, ARTICLE, ASIDE, B, BIG, BLOCKQUOTE, BR, CENTER, CITE, CODE, DD, DEL, DETAILS, DFN, DIV, DL, DT, EM, FIGCAPTION, FIGURE, FONT, FOOTER, HEADER, HR, I, INS, KBD, MAIN, MARK, NAV, NOSCRIPT, P, PRE, Q, RP, RT, RUBY, S, SAMP, SECTION, SMALL, STRIKE, STRONG, STYLE, SUB, SUMMARY, SUP, TT, U, VAR
Everything with screenshot: https://demo.fwfh.dev/supported/tags.html
Try with fwfh.dev

These tags requires flutter_widget_from_html:

AUDIO
IFRAME
SVG
VIDEO

These tags and their contents will be ignored:

SCRIPT
STYLE

Attributes

align: center/end/justify/left/right/start/-moz-center/-webkit-center
dir: auto/ltr/rtl

Inline stylings

background: 1 value (color)
- background-color: currentcolor, hex values, rgb(), hsl() or named colors
- background-image: url() with support for asset (asset://), data uri, local file (file://) and network image
- background-repeat: no-repeat/repeat/repeat-x/repeat-y
- background-position: single or double instances of bottom/center/left/right/top (e.g. top left)
- background-size: auto/contain/cover
border: 3 values (width style color), 2 values (width style) or 1 value (width)
- border-top, border-right, border-bottom, border-left
- border-block-start, border-block-end
- border-inline-start, border-inline-end
border-radius: 4, 3, 2 or 1 value with slash support (e.g. 10px / 20px)
- border-top-left-radius: 2 values or 1 value in em, pt and px
- border-top-right-radius: 2 values or 1 value in em, pt and px
- border-bottom-right-radius: 2 values or 1 value in em, pt and px
- border-bottom-left-radius: 2 values or 1 value in em, pt and px
color: hex values, rgb(), hsl() or named colors
direction (similar to dir attribute)
display: block/flex/inline/inline-block/none
- In flex mode:
  - flex-direction: column/row
  - align-items: flex-start/flex-end/center/baseline/stretch
  - justify-content: flex-start/flex-end/center/space-between/space-around/space-evenly
font-family
font-size: absolute (e.g. xx-large), relative (larger, smaller) or values in em, %, pt and px
font-style: italic/normal
font-weight: bold/normal/100..900
line-height: normal, number or values in em, %, pt and px
margin: 4 values, 2 values or 1 value in em, pt and px
- margin-top, margin-right, margin-bottom, margin-left
- margin-block-start, margin-block-end
- margin-inline-start, margin-inline-end
padding: 4 values, 2 values or 1 value in em, pt and px
- padding-top, padding-right, padding-bottom, padding-left
- padding-block-start, padding-block-end
- padding-inline-start, padding-inline-end
vertical-align: baseline/top/bottom/middle/sub/super
text-align (similar to align attribute)
text-decoration
- text-decoration-color: currentcolor, hex values, rgb(), hsl() or named colors
- text-decoration-line: line-through/none/overline/underline
- text-decoration-style: dotted/dashed/double/solid
- text-decoration-thickness, text-decoration-width: values in % only
text-overflow: clip/ellipsis. Note: text-overflow: ellipsis should be used in conjuntion with max-lines or -webkit-line-clamp for better result.
text-shadow:
- 4 values (color x y blur, color x y blur)
- 3 values (x y color, color x y)
- Or 2 values (x y)
- Multiple shadows
white-space: pre/normal/nowrap
Sizing: auto or values in em, %, pt and px
- width, max-width, min-width
- height, max-height, min-height

Extensibility

This package implements widget building logic with high testing coverage to ensure correctness. It tries to render an optimal tree by using RichText with specific TextStyle, collapsing margins, proper whitespace handling, etc. The idea is to build a solid foundation for apps to customize.

The enhanced package uses a custom WidgetFactory with pre-built mixins for easy usage:

fwfh_cached_network_image for optimized image rendering
fwfh_chewie for VIDEO support
fwfh_just_audio for AUDIO support
fwfh_svg for SVG support
fwfh_url_launcher to launch URLs
fwfh_webview for IFRAME support

See the extensibility document for detailed information.

Flutter Widget from HTML (core)