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Cache parsing results across widget rebuilds #33

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Cache parsing results across widget rebuilds #33

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a7e752d
fix: Cache generated spans across rebuilds
hacker1024 Jun 22, 2022
9ba389f
fix: Don't regenerate nodes on a theme change
hacker1024 Jun 22, 2022
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69 changes: 52 additions & 17 deletions flutter_highlight/lib/flutter_highlight.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ import 'package:flutter/widgets.dart';
import 'package:highlight/highlight.dart' show highlight, Node;

/// Highlight Flutter Widget
class HighlightView extends StatelessWidget {
class HighlightView extends StatefulWidget {
/// The original code to be highlighted
final String source;

Expand Down Expand Up @@ -36,6 +36,23 @@ class HighlightView extends StatelessWidget {
int tabSize = 8, // TODO: https://github.com/flutter/flutter/issues/50087
}) : source = input.replaceAll('\t', ' ' * tabSize);

static const _rootKey = 'root';
static const _defaultFontColor = Color(0xff000000);
static const _defaultBackgroundColor = Color(0xffffffff);

// TODO: dart:io is not available at web platform currently
// See: https://github.com/flutter/flutter/issues/39998
// So we just use monospace here for now
static const _defaultFontFamily = 'monospace';

@override
State<HighlightView> createState() => _HighlightViewState();
}

class _HighlightViewState extends State<HighlightView> {
late List<Node> _nodes;
late List<TextSpan> _spans;

List<TextSpan> _convert(List<Node> nodes) {
List<TextSpan> spans = [];
var currentSpans = spans;
Expand All @@ -45,10 +62,11 @@ class HighlightView extends StatelessWidget {
if (node.value != null) {
currentSpans.add(node.className == null
? TextSpan(text: node.value)
: TextSpan(text: node.value, style: theme[node.className!]));
: TextSpan(text: node.value, style: widget.theme[node.className!]));
} else if (node.children != null) {
List<TextSpan> tmp = [];
currentSpans.add(TextSpan(children: tmp, style: theme[node.className!]));
currentSpans
.add(TextSpan(children: tmp, style: widget.theme[node.className!]));
stack.add(currentSpans);
currentSpans = tmp;

Expand All @@ -68,32 +86,49 @@ class HighlightView extends StatelessWidget {
return spans;
}

static const _rootKey = 'root';
static const _defaultFontColor = Color(0xff000000);
static const _defaultBackgroundColor = Color(0xffffffff);
void _parse() =>
_nodes = highlight.parse(widget.source, language: widget.language).nodes!;

// TODO: dart:io is not available at web platform currently
// See: https://github.com/flutter/flutter/issues/39998
// So we just use monospace here for now
static const _defaultFontFamily = 'monospace';
void _generateSpans() => _spans = _convert(_nodes);

@override
void initState() {
super.initState();
_parse();
_generateSpans();
}

@override
void didUpdateWidget(HighlightView oldWidget) {
super.didUpdateWidget(oldWidget);
if (widget.source != oldWidget.source ||
widget.language != oldWidget.language) {
_parse();
_generateSpans();
} else if (widget.theme != oldWidget.theme) {
_generateSpans();
}
}

@override
Widget build(BuildContext context) {
var _textStyle = TextStyle(
fontFamily: _defaultFontFamily,
color: theme[_rootKey]?.color ?? _defaultFontColor,
fontFamily: HighlightView._defaultFontFamily,
color: widget.theme[HighlightView._rootKey]?.color ??
HighlightView._defaultFontColor,
);
if (textStyle != null) {
_textStyle = _textStyle.merge(textStyle);
if (widget.textStyle != null) {
_textStyle = _textStyle.merge(widget.textStyle);
}

return Container(
color: theme[_rootKey]?.backgroundColor ?? _defaultBackgroundColor,
padding: padding,
color: widget.theme[HighlightView._rootKey]?.backgroundColor ??
HighlightView._defaultBackgroundColor,
padding: widget.padding,
child: RichText(
text: TextSpan(
style: _textStyle,
children: _convert(highlight.parse(source, language: language).nodes!),
children: _spans,
),
),
);
Expand Down