From a21b2be8bba87586b8d4f775ce4a0ff1ac239eaa Mon Sep 17 00:00:00 2001
From: Mouad Debbar <mouad.debbar@gmail.com>
Date: Wed, 13 Jan 2021 11:54:02 -0800
Subject: [PATCH] [web] Fix layout exception when text is null
 (flutter/engine#23653)

---
 .../lib/web_ui/lib/src/engine/text/layout_service.dart |  4 ++++
 .../web_ui/test/text/layout_service_plain_test.dart    | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/engine/src/flutter/lib/web_ui/lib/src/engine/text/layout_service.dart b/engine/src/flutter/lib/web_ui/lib/src/engine/text/layout_service.dart
index edd1938a5be..b5a57755bd1 100644
--- a/engine/src/flutter/lib/web_ui/lib/src/engine/text/layout_service.dart
+++ b/engine/src/flutter/lib/web_ui/lib/src/engine/text/layout_service.dart
@@ -71,6 +71,10 @@ class TextLayoutService {
     didExceedMaxLines = false;
     lines.clear();
 
+    if (spanCount == 0) {
+      return;
+    }
+
     final Spanometer spanometer = Spanometer(paragraph, context);
 
     int spanIndex = 0;
diff --git a/engine/src/flutter/lib/web_ui/test/text/layout_service_plain_test.dart b/engine/src/flutter/lib/web_ui/test/text/layout_service_plain_test.dart
index 4187ee3a7bb..811faf01139 100644
--- a/engine/src/flutter/lib/web_ui/test/text/layout_service_plain_test.dart
+++ b/engine/src/flutter/lib/web_ui/test/text/layout_service_plain_test.dart
@@ -42,6 +42,16 @@ void main() {
 void testMain() async {
   await ui.webOnlyInitializeTestDomRenderer();
 
+  test('no text', () {
+    final CanvasParagraph paragraph = CanvasParagraphBuilder(ahemStyle).build();
+    paragraph.layout(constrain(double.infinity));
+
+    expect(paragraph.maxIntrinsicWidth, 0);
+    expect(paragraph.minIntrinsicWidth, 0);
+    expect(paragraph.height, 0);
+    expect(paragraph.computeLineMetrics(), isEmpty);
+  });
+
   test('preserves whitespace when measuring', () {
     CanvasParagraph paragraph;