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Description:

flutter widget from html

Flutter Widget from HTML #

Flutter package to render html as widgets that supports hyperlink, image, audio, video, iframe
and 70+ other tags.

Live demo

This package supports most common HTML tags for easy usage.
If you don't want to include all of its dependencies in your build, it's possible to use flutter_widget_from_html_core with a subset of the mixins to control your app size:

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

Getting Started #
Add this to your app's pubspec.yaml file:
dependencies:
flutter_widget_from_html: ^0.15.2
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Platform specific configuration #
iOS
This package uses just_audio to play audio and this dependency uses a microphone API.
By default, the App Store requires a usage description which can be skipped by editing your ios/Podfile.
See the detailed instruction on its pub.dev page.
If you don't need AUDIO tag support (e.g. your HTML never has that tag), it may be better to switch to
the core package and use it with a subset of the mixins. See Extensibility for more details.
Usage #
Then you have to import the package with:
import 'package:flutter_widget_from_html/flutter_widget_from_html.dart';
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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 block widget that takes the full width
return FooBarWidget();
}

if (element.attributes['fizz'] == 'buzz') {
// render a custom widget inline 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),
),
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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

Scroll to anchor
Launch URL via url_launcher with base URL resolver

AUDIO via just_audio
H1/H2/H3/H4/H5/H6
IFRAME via webview_flutter
IMG with support for asset (asset://), data uri, local file (file://) and network image via cached_network_image. Additional .svg file support via flutter_svg.
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

SVG via flutter_svg
VIDEO via chewie
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 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 #
The core 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, merging text spans together, showing images in sized box, etc. The idea is to build a solid foundation for apps to customize.
See the extensibility document for detailed information.