lib/web_ui/lib/src/engine/canvaskit/fonts.dart - mirrors/engine - Git at Google

 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:async';
 import 'dart:convert';
 import 'dart:typed_data';

 import 'package:web_test_fonts/web_test_fonts.dart';

 import '../assets.dart';
 import '../dom.dart';
 import '../fonts.dart';
 import '../util.dart';
 import 'canvaskit_api.dart';
 import 'font_fallbacks.dart';

 // This URL was found by using the Google Fonts Developer API to find the URL
 // for Roboto. The API warns that this URL is not stable. In order to update
 // this, list out all of the fonts and find the URL for the regular
 // Roboto font. The API reference is here:
 // https://developers.google.com/fonts/docs/developer_api
 const String _robotoUrl =
     'https://fonts.gstatic.com/s/roboto/v20/KFOmCnqEu92Fr1Me5WZLCzYlKw.ttf';

 /// Manages the fonts used in the Skia-based backend.
 class SkiaFontCollection implements FlutterFontCollection {
   final Set<String> _downloadedFontFamilies = <String>{};

   /// Fonts that started the download process, but are not yet registered.
   ///
   /// /// Once downloaded successfully, this map is cleared and the resulting
   /// [UnregisteredFont]s are added to [_registeredFonts].
   final List<UnregisteredFont> _unregisteredFonts = <UnregisteredFont>[];

   final List<RegisteredFont> _registeredFonts = <RegisteredFont>[];

   /// Returns fonts that have been downloaded, registered, and parsed.
   ///
   /// This should only be used in tests.
   List<RegisteredFont>? get debugRegisteredFonts {
     if (!assertionsEnabled) {
       return null;
     }
     return _registeredFonts;
   }

   final Map<String, List<SkFont>> familyToFontMap = <String, List<SkFont>>{};

   void _registerWithFontProvider() {
     if (_fontProvider != null) {
       _fontProvider!.delete();
       _fontProvider = null;
       skFontCollection?.delete();
       skFontCollection = null;
     }
     _fontProvider = canvasKit.TypefaceFontProvider.Make();
     skFontCollection = canvasKit.FontCollection.Make();
     skFontCollection!.enableFontFallback();
     skFontCollection!.setDefaultFontManager(_fontProvider);
     familyToFontMap.clear();

     for (final RegisteredFont font in _registeredFonts) {
       _fontProvider!.registerFont(font.bytes, font.family);
       familyToFontMap
           .putIfAbsent(font.family, () => <SkFont>[])
           .add(SkFont(font.typeface));
     }

     for (final RegisteredFont font
         in FontFallbackData.instance.registeredFallbackFonts) {
       _fontProvider!.registerFont(font.bytes, font.family);
       familyToFontMap
           .putIfAbsent(font.family, () => <SkFont>[])
           .add(SkFont(font.typeface));
     }
   }

   @override
   Future<void> loadFontFromList(Uint8List list, {String? fontFamily}) async {
     if (fontFamily == null) {
       fontFamily = _readActualFamilyName(list);
       if (fontFamily == null) {
         printWarning('Failed to read font family name. Aborting font load.');
         return;
       }
     }

     final SkTypeface? typeface =
         canvasKit.Typeface.MakeFreeTypeFaceFromData(list.buffer);
     if (typeface != null) {
       _registeredFonts.add(RegisteredFont(list, fontFamily, typeface));
       _registerWithFontProvider();
     } else {
       printWarning('Failed to parse font family "$fontFamily"');
       return;
     }
   }

   /// Loads fonts from `FontManifest.json`.
   @override
   Future<void> downloadAssetFonts(AssetManager assetManager) async {
     final HttpFetchResponse response = await assetManager.loadAsset('FontManifest.json');

     if (!response.hasPayload) {
       printWarning('Font manifest does not exist at `${response.url}` - ignoring.');
       return;
     }

     final Uint8List data = await response.asUint8List();
     final List<dynamic>? fontManifest = json.decode(utf8.decode(data)) as List<dynamic>?;
     if (fontManifest == null) {
       throw AssertionError(
           'There was a problem trying to load FontManifest.json');
     }

     final List<Future<UnregisteredFont?>> pendingFonts = <Future<UnregisteredFont?>>[];

     for (final Map<String, dynamic> fontFamily
         in fontManifest.cast<Map<String, dynamic>>()) {
       final String family = fontFamily.readString('family');
       final List<dynamic> fontAssets = fontFamily.readList('fonts');
       for (final dynamic fontAssetItem in fontAssets) {
         final Map<String, dynamic> fontAsset = fontAssetItem as Map<String, dynamic>;
         final String asset = fontAsset.readString('asset');
         _downloadFont(pendingFonts, assetManager.getAssetUrl(asset), family);
       }
     }

     /// We need a default fallback font for CanvasKit, in order to
     /// avoid crashing while laying out text with an unregistered font. We chose
     /// Roboto to match Android.
     if (!_isFontFamilyDownloaded('Roboto')) {
       // Download Roboto and add it to the font buffers.
       _downloadFont(pendingFonts, _robotoUrl, 'Roboto');
     }

     final List<UnregisteredFont?> completedPendingFonts = await Future.wait(pendingFonts);
     _unregisteredFonts.addAll(completedPendingFonts.whereType<UnregisteredFont>());
   }

   @override
   void registerDownloadedFonts() {
     RegisteredFont? makeRegisterFont(ByteBuffer buffer, String url, String family) {
       final Uint8List bytes = buffer.asUint8List();
       final SkTypeface? typeface =
           canvasKit.Typeface.MakeFreeTypeFaceFromData(bytes.buffer);
       if (typeface != null) {
         return RegisteredFont(bytes, family, typeface);
       } else {
         printWarning('Failed to load font $family at $url');
         printWarning('Verify that $url contains a valid font.');
         return null;
       }
     }

     for (final UnregisteredFont unregisteredFont in _unregisteredFonts) {
       final RegisteredFont? registeredFont = makeRegisterFont(
         unregisteredFont.bytes,
         unregisteredFont.url,
         unregisteredFont.family
       );
       if (registeredFont != null) {
         _registeredFonts.add(registeredFont);
       }
     }

     _unregisteredFonts.clear();
     _registerWithFontProvider();
   }

   /// Whether the [fontFamily] was registered and/or loaded.
   bool _isFontFamilyDownloaded(String fontFamily) {
     return _downloadedFontFamilies.contains(fontFamily);
   }

   /// Loads the Ahem font, unless it's already been loaded using
   /// `FontManifest.json` (see [downloadAssetFonts]).
   ///
   /// `FontManifest.json` has higher priority than the default test font URLs.
   /// This allows customizing test environments where fonts are loaded from
   /// different URLs.
   @override
   Future<void> debugDownloadTestFonts() async {
     final List<Future<UnregisteredFont?>> pendingFonts = <Future<UnregisteredFont?>>[];
     for (final MapEntry<String, String> fontEntry in testFontUrls.entries) {
       if (!_isFontFamilyDownloaded(fontEntry.key)) {
         _downloadFont(pendingFonts, fontEntry.value, fontEntry.key);
       }
     }
     final List<UnregisteredFont?> completedPendingFonts = await Future.wait(pendingFonts);
     final List<UnregisteredFont> fonts = <UnregisteredFont>[
       UnregisteredFont(
         EmbeddedTestFont.flutterTest.data.buffer,
         '<embedded>',
         EmbeddedTestFont.flutterTest.fontFamily,
       ),
       ...completedPendingFonts.whereType<UnregisteredFont>(),
     ];
     _unregisteredFonts.addAll(fonts);

     // Ahem must be added to font fallbacks list regardless of where it was
     // downloaded from.
     FontFallbackData.instance.globalFontFallbacks.add(ahemFontFamily);
   }

   void _downloadFont(
     List<Future<UnregisteredFont?>> waitUnregisteredFonts,
     String url,
     String family
   ) {
     Future<UnregisteredFont?> downloadFont() async {
       // Try to get the font leniently. Do not crash the app when failing to
       // fetch the font in the spirit of "gradual degradation of functionality".
       try {
         final ByteBuffer data = await httpFetchByteBuffer(url);
         return UnregisteredFont(data, url, family);
       } catch (e) {
         printWarning('Failed to load font $family at $url');
         printWarning(e.toString());
         return null;
       }
     }

     _downloadedFontFamilies.add(family);
     waitUnregisteredFonts.add(downloadFont());
   }


   String? _readActualFamilyName(Uint8List bytes) {
     final SkFontMgr tmpFontMgr =
         canvasKit.FontMgr.FromData(<Uint8List>[bytes])!;
     final String? actualFamily = tmpFontMgr.getFamilyName(0);
     tmpFontMgr.delete();
     return actualFamily;
   }

   TypefaceFontProvider? _fontProvider;
   SkFontCollection? skFontCollection;

   @override
   void clear() {}
 }

 /// Represents a font that has been registered.
 class RegisteredFont {
   RegisteredFont(this.bytes, this.family, this.typeface) {
     // This is a hack which causes Skia to cache the decoded font.
     final SkFont skFont = SkFont(typeface);
     skFont.getGlyphBounds(<int>[0], null, null);
   }

   /// The font family name for this font.
   final String family;

   /// The byte data for this font.
   final Uint8List bytes;

   /// The [SkTypeface] created from this font's [bytes].
   ///
   /// This is used to determine which code points are supported by this font.
   final SkTypeface typeface;
 }

 /// Represents a font that has been downloaded but not registered.
 class UnregisteredFont {
   const UnregisteredFont(this.bytes, this.url, this.family);
   final ByteBuffer bytes;
   final String url;
   final String family;
 }
	// Copyright 2013 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:async';
	import 'dart:convert';
	import 'dart:typed_data';

	import 'package:web_test_fonts/web_test_fonts.dart';

	import '../assets.dart';
	import '../dom.dart';
	import '../fonts.dart';
	import '../util.dart';
	import 'canvaskit_api.dart';
	import 'font_fallbacks.dart';

	// This URL was found by using the Google Fonts Developer API to find the URL
	// for Roboto. The API warns that this URL is not stable. In order to update
	// this, list out all of the fonts and find the URL for the regular
	// Roboto font. The API reference is here:
	// https://developers.google.com/fonts/docs/developer_api
	const String _robotoUrl =
	'https://fonts.gstatic.com/s/roboto/v20/KFOmCnqEu92Fr1Me5WZLCzYlKw.ttf';

	/// Manages the fonts used in the Skia-based backend.
	class SkiaFontCollection implements FlutterFontCollection {
	final Set<String> _downloadedFontFamilies = <String>{};

	/// Fonts that started the download process, but are not yet registered.
	///
	/// /// Once downloaded successfully, this map is cleared and the resulting
	/// [UnregisteredFont]s are added to [_registeredFonts].
	final List<UnregisteredFont> _unregisteredFonts = <UnregisteredFont>[];

	final List<RegisteredFont> _registeredFonts = <RegisteredFont>[];

	/// Returns fonts that have been downloaded, registered, and parsed.
	///
	/// This should only be used in tests.
	List<RegisteredFont>? get debugRegisteredFonts {
	if (!assertionsEnabled) {
	return null;
	}
	return _registeredFonts;
	}

	final Map<String, List<SkFont>> familyToFontMap = <String, List<SkFont>>{};

	void _registerWithFontProvider() {
	if (_fontProvider != null) {
	_fontProvider!.delete();
	_fontProvider = null;
	skFontCollection?.delete();
	skFontCollection = null;
	}
	_fontProvider = canvasKit.TypefaceFontProvider.Make();
	skFontCollection = canvasKit.FontCollection.Make();
	skFontCollection!.enableFontFallback();
	skFontCollection!.setDefaultFontManager(_fontProvider);
	familyToFontMap.clear();

	for (final RegisteredFont font in _registeredFonts) {
	_fontProvider!.registerFont(font.bytes, font.family);
	familyToFontMap
	.putIfAbsent(font.family, () => <SkFont>[])
	.add(SkFont(font.typeface));
	}

	for (final RegisteredFont font
	in FontFallbackData.instance.registeredFallbackFonts) {
	_fontProvider!.registerFont(font.bytes, font.family);
	familyToFontMap
	.putIfAbsent(font.family, () => <SkFont>[])
	.add(SkFont(font.typeface));
	}
	}

	@override
	Future<void> loadFontFromList(Uint8List list, {String? fontFamily}) async {
	if (fontFamily == null) {
	fontFamily = _readActualFamilyName(list);
	if (fontFamily == null) {
	printWarning('Failed to read font family name. Aborting font load.');
	return;
	}
	}

	final SkTypeface? typeface =
	canvasKit.Typeface.MakeFreeTypeFaceFromData(list.buffer);
	if (typeface != null) {
	_registeredFonts.add(RegisteredFont(list, fontFamily, typeface));
	_registerWithFontProvider();
	} else {
	printWarning('Failed to parse font family "$fontFamily"');
	return;
	}
	}

	/// Loads fonts from `FontManifest.json`.
	@override
	Future<void> downloadAssetFonts(AssetManager assetManager) async {
	final HttpFetchResponse response = await assetManager.loadAsset('FontManifest.json');

	if (!response.hasPayload) {
	printWarning('Font manifest does not exist at `${response.url}` - ignoring.');
	return;
	}

	final Uint8List data = await response.asUint8List();
	final List<dynamic>? fontManifest = json.decode(utf8.decode(data)) as List<dynamic>?;
	if (fontManifest == null) {
	throw AssertionError(
	'There was a problem trying to load FontManifest.json');
	}

	final List<Future<UnregisteredFont?>> pendingFonts = <Future<UnregisteredFont?>>[];

	for (final Map<String, dynamic> fontFamily
	in fontManifest.cast<Map<String, dynamic>>()) {
	final String family = fontFamily.readString('family');
	final List<dynamic> fontAssets = fontFamily.readList('fonts');
	for (final dynamic fontAssetItem in fontAssets) {
	final Map<String, dynamic> fontAsset = fontAssetItem as Map<String, dynamic>;
	final String asset = fontAsset.readString('asset');
	_downloadFont(pendingFonts, assetManager.getAssetUrl(asset), family);
	}
	}

	/// We need a default fallback font for CanvasKit, in order to
	/// avoid crashing while laying out text with an unregistered font. We chose
	/// Roboto to match Android.
	if (!_isFontFamilyDownloaded('Roboto')) {
	// Download Roboto and add it to the font buffers.
	_downloadFont(pendingFonts, _robotoUrl, 'Roboto');
	}

	final List<UnregisteredFont?> completedPendingFonts = await Future.wait(pendingFonts);
	_unregisteredFonts.addAll(completedPendingFonts.whereType<UnregisteredFont>());
	}

	@override
	void registerDownloadedFonts() {
	RegisteredFont? makeRegisterFont(ByteBuffer buffer, String url, String family) {
	final Uint8List bytes = buffer.asUint8List();
	final SkTypeface? typeface =
	canvasKit.Typeface.MakeFreeTypeFaceFromData(bytes.buffer);
	if (typeface != null) {
	return RegisteredFont(bytes, family, typeface);
	} else {
	printWarning('Failed to load font $family at $url');
	printWarning('Verify that $url contains a valid font.');
	return null;
	}
	}

	for (final UnregisteredFont unregisteredFont in _unregisteredFonts) {
	final RegisteredFont? registeredFont = makeRegisterFont(
	unregisteredFont.bytes,
	unregisteredFont.url,
	unregisteredFont.family
	);
	if (registeredFont != null) {
	_registeredFonts.add(registeredFont);
	}
	}

	_unregisteredFonts.clear();
	_registerWithFontProvider();
	}

	/// Whether the [fontFamily] was registered and/or loaded.
	bool _isFontFamilyDownloaded(String fontFamily) {
	return _downloadedFontFamilies.contains(fontFamily);
	}

	/// Loads the Ahem font, unless it's already been loaded using
	/// `FontManifest.json` (see [downloadAssetFonts]).
	///
	/// `FontManifest.json` has higher priority than the default test font URLs.
	/// This allows customizing test environments where fonts are loaded from
	/// different URLs.
	@override
	Future<void> debugDownloadTestFonts() async {
	final List<Future<UnregisteredFont?>> pendingFonts = <Future<UnregisteredFont?>>[];
	for (final MapEntry<String, String> fontEntry in testFontUrls.entries) {
	if (!_isFontFamilyDownloaded(fontEntry.key)) {
	_downloadFont(pendingFonts, fontEntry.value, fontEntry.key);
	}
	}
	final List<UnregisteredFont?> completedPendingFonts = await Future.wait(pendingFonts);
	final List<UnregisteredFont> fonts = <UnregisteredFont>[
	UnregisteredFont(
	EmbeddedTestFont.flutterTest.data.buffer,
	'<embedded>',
	EmbeddedTestFont.flutterTest.fontFamily,
	),
	...completedPendingFonts.whereType<UnregisteredFont>(),
	];
	_unregisteredFonts.addAll(fonts);

	// Ahem must be added to font fallbacks list regardless of where it was
	// downloaded from.
	FontFallbackData.instance.globalFontFallbacks.add(ahemFontFamily);
	}

	void _downloadFont(
	List<Future<UnregisteredFont?>> waitUnregisteredFonts,
	String url,
	String family
	) {
	Future<UnregisteredFont?> downloadFont() async {
	// Try to get the font leniently. Do not crash the app when failing to
	// fetch the font in the spirit of "gradual degradation of functionality".
	try {
	final ByteBuffer data = await httpFetchByteBuffer(url);
	return UnregisteredFont(data, url, family);
	} catch (e) {
	printWarning('Failed to load font $family at $url');
	printWarning(e.toString());
	return null;
	}
	}

	_downloadedFontFamilies.add(family);
	waitUnregisteredFonts.add(downloadFont());
	}


	String? _readActualFamilyName(Uint8List bytes) {
	final SkFontMgr tmpFontMgr =
	canvasKit.FontMgr.FromData(<Uint8List>[bytes])!;
	final String? actualFamily = tmpFontMgr.getFamilyName(0);
	tmpFontMgr.delete();
	return actualFamily;
	}

	TypefaceFontProvider? _fontProvider;
	SkFontCollection? skFontCollection;

	@override
	void clear() {}
	}

	/// Represents a font that has been registered.
	class RegisteredFont {
	RegisteredFont(this.bytes, this.family, this.typeface) {
	// This is a hack which causes Skia to cache the decoded font.
	final SkFont skFont = SkFont(typeface);
	skFont.getGlyphBounds(<int>[0], null, null);
	}

	/// The font family name for this font.
	final String family;

	/// The byte data for this font.
	final Uint8List bytes;

	/// The [SkTypeface] created from this font's [bytes].
	///
	/// This is used to determine which code points are supported by this font.
	final SkTypeface typeface;
	}

	/// Represents a font that has been downloaded but not registered.
	class UnregisteredFont {
	const UnregisteredFont(this.bytes, this.url, this.family);
	final ByteBuffer bytes;
	final String url;
	final String family;
	}