From f79cfcc0d38681b1abbb2e1168933db38f947059 Mon Sep 17 00:00:00 2001
From: Jackson Gardner <jacksongardner@google.com>
Date: Fri, 22 Mar 2024 12:22:22 -0700
Subject: [PATCH] [Skwasm] Respect the `debugDisableFallbackFonts` flag.
 (flutter/engine#51626)

Skwasm needs to respect the `debugDisableFallbackFonts` flag, which is used by framework tests.
---
 .../engine/skwasm/skwasm_impl/paragraph.dart  |  2 +-
 .../test/ui/fallback_fonts_golden_test.dart   | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/engine/src/flutter/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/paragraph.dart b/engine/src/flutter/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/paragraph.dart
index e872c768a3a..97c5b173b1b 100644
--- a/engine/src/flutter/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/paragraph.dart
+++ b/engine/src/flutter/lib/web_ui/lib/src/engine/skwasm/skwasm_impl/paragraph.dart
@@ -113,7 +113,7 @@ class SkwasmParagraph extends SkwasmObjectWrapper<RawParagraph> implements ui.Pa
   @override
   void layout(ui.ParagraphConstraints constraints) {
     paragraphLayout(handle, constraints.width);
-    if (!_hasCheckedForMissingCodePoints) {
+    if (!debugDisableFontFallbacks && !_hasCheckedForMissingCodePoints) {
       _hasCheckedForMissingCodePoints = true;
       final int missingCodePointCount = paragraphGetUnresolvedCodePoints(handle, nullptr, 0);
       if (missingCodePointCount > 0) {
diff --git a/engine/src/flutter/lib/web_ui/test/ui/fallback_fonts_golden_test.dart b/engine/src/flutter/lib/web_ui/test/ui/fallback_fonts_golden_test.dart
index 4570bf24048..621a9a3334d 100644
--- a/engine/src/flutter/lib/web_ui/test/ui/fallback_fonts_golden_test.dart
+++ b/engine/src/flutter/lib/web_ui/test/ui/fallback_fonts_golden_test.dart
@@ -431,6 +431,26 @@ void testMain() {
         }
       }
     });
+
+    test('fallback fonts do not download when debugDisableFontFallbacks is set', () async {
+      debugDisableFontFallbacks = true;
+
+      expect(renderer.fontCollection.fontFallbackManager!.globalFontFallbacks, <String>['Roboto']);
+
+      // Creating this paragraph would cause us to start to download the
+      // fallback font if we didn't disable font fallbacks.
+      final ui.ParagraphBuilder pb = ui.ParagraphBuilder(
+        ui.ParagraphStyle(),
+      );
+      pb.addText('Hello 😊');
+      pb.build().layout(const ui.ParagraphConstraints(width: 1000));
+
+      await renderer.fontCollection.fontFallbackManager!.debugWhenIdle();
+
+      // Make sure we didn't download the fallback font.
+      expect(renderer.fontCollection.fontFallbackManager!.globalFontFallbacks,
+          isNot(contains('Noto Color Emoji')));
+    });
   },
   // HTML renderer doesn't use the fallback font manager.
   skip: isHtml,