Skip to content
This repository was archived by the owner on Feb 25, 2025. It is now read-only.

delete fontface polyfill #37652

Merged
alanwutang11 merged 3 commits into from
Nov 17, 2022
Merged

delete fontface polyfill #37652

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
56044b3
delete fontface polyfill
alanwutang11 Nov 16, 2022
09f3939
removed fonts clear and factory constructor
alanwutang11 Nov 17, 2022
15115fb
addressed comments
alanwutang11 Nov 17, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 0 additions & 7 deletions lib/web_ui/lib/src/engine/safe_browser_api.dart
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -134,13 +134,6 @@ num? parseFloat(String source) {
return result;
}

final bool supportsFontLoadingApi =
js_util.hasProperty(domWindow, 'FontFace');

final bool supportsFontsClearApi =
js_util.hasProperty(domDocument, 'fonts') &&
js_util.hasProperty(domDocument.fonts!, 'clear');

/// Used to decide if the browser tab still has the focus.
///
/// This information is useful for deciding on the blur behavior.
Expand Down
120 changes: 3 additions & 117 deletions lib/web_ui/lib/src/engine/text/font_collection.dart
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -48,11 +48,7 @@ class HtmlFontCollection implements FontCollection {
'There was a problem trying to load FontManifest.json');
}

if (supportsFontLoadingApi) {
_assetFontManager = FontManager();
} else {
_assetFontManager = _PolyfillFontManager();
}
_assetFontManager = FontManager();

for (final Map<String, dynamic> fontFamily
in fontManifest.cast<Map<String, dynamic>>()) {
Expand Down Expand Up @@ -106,23 +102,14 @@ class HtmlFontCollection implements FontCollection {
void clear() {
_assetFontManager = null;
_testFontManager = null;
if (supportsFontsClearApi) {
domDocument.fonts!.clear();
}
domDocument.fonts!.clear();
}
}

/// Manages a collection of fonts and ensures they are loaded.
class FontManager {
factory FontManager() {
if (supportsFontLoadingApi) {
return FontManager._();
} else {
return _PolyfillFontManager();
}
}

FontManager._();
FontManager();

/// Fonts that started the downloading process. Once the fonts have downloaded
/// without error, they are moved to [_downloadedFonts]. Those fonts
Expand Down Expand Up @@ -243,104 +230,3 @@ class FontManager {
});
}
}

/// A font manager that works without using the CSS Font Loading API.
///
/// The CSS Font Loading API is not implemented in IE 11 or Edge. To tell if a
/// font is loaded, we continuously measure some text using that font until the
/// width changes.
class _PolyfillFontManager extends FontManager {
_PolyfillFontManager() : super._();

/// A String containing characters whose width varies greatly between fonts.
static const String _testString = 'giItT1WQy@!-/#';

static const Duration _fontLoadTimeout = Duration(seconds: 2);
static const Duration _fontLoadRetryDuration = Duration(milliseconds: 50);

final List<Future<void>> _completerFutures = <Future<void>>[];

@override
Future<void> downloadAllFonts() async {
await Future.wait(_completerFutures);
}

@override
void registerDownloadedFonts() {}

@override
void downloadAsset(
String family,
String asset,
Map<String, String> descriptors,
) {
final DomHTMLParagraphElement paragraph = createDomHTMLParagraphElement();
paragraph.style.position = 'absolute';
paragraph.style.visibility = 'hidden';
paragraph.style.fontSize = '72px';
const String fallbackFontName = 'sans-serif';
paragraph.style.fontFamily = fallbackFontName;
if (descriptors['style'] != null) {
paragraph.style.fontStyle = descriptors['style']!;
}
if (descriptors['weight'] != null) {
paragraph.style.fontWeight = descriptors['weight']!;
}
paragraph.text = _testString;

domDocument.body!.append(paragraph);
final int sansSerifWidth = paragraph.offsetWidth;

paragraph.style.fontFamily = "'$family', $fallbackFontName";

final Completer<void> completer = Completer<void>();

late DateTime fontLoadStart;

void watchWidth() {
if (paragraph.offsetWidth != sansSerifWidth) {
paragraph.remove();
completer.complete();
} else {
if (DateTime.now().difference(fontLoadStart) > _fontLoadTimeout) {
// Let application waiting for fonts continue with fallback.
completer.complete();
// Throw unhandled exception for logging.
throw Exception('Timed out trying to load font: $family');
} else {
Timer(_fontLoadRetryDuration, watchWidth);
}
}
}

final Map<String, String?> fontStyleMap = <String, String?>{};
fontStyleMap['font-family'] = "'$family'";
fontStyleMap['src'] = asset;
if (descriptors['style'] != null) {
fontStyleMap['font-style'] = descriptors['style'];
}
if (descriptors['weight'] != null) {
fontStyleMap['font-weight'] = descriptors['weight'];
}
final String fontFaceDeclaration = fontStyleMap.keys
.map((String name) => '$name: ${fontStyleMap[name]};')
.join(' ');
final DomHTMLStyleElement fontLoadStyle = createDomHTMLStyleElement();
fontLoadStyle.type = 'text/css';
fontLoadStyle.innerHtml = '@font-face { $fontFaceDeclaration }';
domDocument.head!.append(fontLoadStyle);

// HACK: If this is an icon font, then when it loads it won't change the
// width of our test string. So we just have to hope it loads before the
// layout phase.
if (family.toLowerCase().contains('icon')) {
paragraph.remove();
return;
}

fontLoadStart = DateTime.now();
watchWidth();

_completerFutures.add(completer.future);
}
}