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KatexWidget: Cache the generated images

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The file is stored in the tmp dir with the filename of
"katex_$HASH$.png" where $HASH$ is the md5 hash of the input string to
be rendered.

The cache isn't ever cleared so far, but maybe the underlying OS will do
that automatically?

Related to #125
This commit is contained in:
Vishesh Handa
2020-05-19 19:40:30 +02:00
parent 9167398309
commit e047787e29
1 changed files with 14 additions and 17 deletions
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31
lib/widgets/katex_widget.dart
View File

@ -1,4 +1,5 @@
import 'dart:async'; import 'dart:async';
import 'dart:convert';
import 'dart:io'; import 'dart:io';
import 'package:flutter/material.dart'; import 'package:flutter/material.dart';
@ -6,6 +7,7 @@ import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart'; import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';
import 'package:path/path.dart' as p; import 'package:path/path.dart' as p;
import 'package:mutex/mutex.dart'; import 'package:mutex/mutex.dart';
import 'package:crypto/crypto.dart';
class KatexWidget extends StatefulWidget { class KatexWidget extends StatefulWidget {
final String input; final String input;
@ -30,6 +32,9 @@ class _KatexWidgetState extends State<KatexWidget> {
void initState() { void initState() {
super.initState(); super.initState();
var inputHash = md5.convert(utf8.encode(widget.input)).toString();
imagePath = p.join(Directory.systemTemp.path, "katex_$inputHash.png");
jsChannel = JavascriptChannel( jsChannel = JavascriptChannel(
name: 'Print', name: 'Print',
onMessageReceived: (JavascriptMessage message) { onMessageReceived: (JavascriptMessage message) {
@ -37,23 +42,11 @@ class _KatexWidgetState extends State<KatexWidget> {
print(message.message); print(message.message);
var uri = UriData.parse(message.message); var uri = UriData.parse(message.message);
File(imagePath).writeAsBytesSync(uri.contentAsBytes());
String tmpFile; // Underlying image file has been modified
var num = 0;
while (true) {
tmpFile = p.join(Directory.systemTemp.path, "katex_$num.png");
if (!File(tmpFile).existsSync()) {
break;
}
num += 1;
}
File(tmpFile).writeAsBytesSync(uri.contentAsBytes());
if (mounted) { if (mounted) {
setState(() { setState(() {});
print("State has been set $tmpFile");
imagePath = tmpFile;
});
} }
flutterWebViewPlugin.close(); flutterWebViewPlugin.close();
@ -65,7 +58,11 @@ class _KatexWidgetState extends State<KatexWidget> {
}, },
); );
_initAsync(); if (File(imagePath).existsSync()) {
print("Katex ${widget.input} in cache");
} else {
_initAsync();
}
} }
void _initAsync() async { void _initAsync() async {
@ -119,7 +116,7 @@ html2canvas(document.body, {backgroundColor: 'rgba(0, 0, 0, 0)', removeContainer
@override @override
Widget build(BuildContext context) { Widget build(BuildContext context) {
if (imagePath == null) { if (!File(imagePath).existsSync()) {
return Container(); return Container();
} }