From 05e7c5428f4e514d2c714789a75c1d294c4308d7 Mon Sep 17 00:00:00 2001
From: Chris Bobbe <cbobbe@zulip.com>
Date: Wed, 6 Mar 2024 17:51:04 -0800
Subject: [PATCH] text: Set 0 letter spacing throughout zulipTypography
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This zeroes out the letter spacing in message content (#545), and
also everywhere else that uses styles from zulipTypography without
overriding the letter spacing.

It's worth mentioning that letter spacing is one of the parameters
that are carefully chosen for the 15 TextThemes that make up the
default Typography in Material 3:

  {display,headline,title,label,body} × {small,medium,large}

So this might be considered a regression...if the Material spec were
our primary or only source of truth for text styles. But it isn't:
we have a designer (Vlad), and this change brings us closer to his
specified design. See #545 and #548.

I also checked to see if the Material 3 default varies the letter
spacing among the three [ScriptCategory]ies (englishLike, dense, and
tall), which might be a reason to ask Vlad if we want to do the
same. But the letter-spacing values are the same across the
[ScriptCategory]ies, so no need for that.

After this, there's still more to do for #548:

- letter spacing of 1% (i.e., 0.01 times `fontSize`) in buttons
- perhaps audit for UI code that's meant to follow Figma already,
  but where we failed to set a non-zero letter spacing that was
  specified in Figma

Fixes: #545
Fixes-partly: #548
---
 lib/widgets/text.dart       | 4 ++++
 test/flutter_checks.dart    | 1 +
 test/widgets/text_test.dart | 7 +++++++
 3 files changed, 12 insertions(+)

diff --git a/lib/widgets/text.dart b/lib/widgets/text.dart
index 2d144a10a5a..dab42fd8836 100644
--- a/lib/widgets/text.dart
+++ b/lib/widgets/text.dart
@@ -36,6 +36,10 @@ Typography zulipTypography(BuildContext context) {
 
   convertGeometry(TextTheme inputTextTheme) {
     TextTheme result = _weightVariableTextTheme(context, inputTextTheme);
+
+    result = _convertTextTheme(result, (maybeInputStyle, _) =>
+      maybeInputStyle?.merge(const TextStyle(letterSpacing: 0)));
+
     return result;
   }
 
diff --git a/test/flutter_checks.dart b/test/flutter_checks.dart
index 4344cc7ad1c..eed202ad68b 100644
--- a/test/flutter_checks.dart
+++ b/test/flutter_checks.dart
@@ -59,6 +59,7 @@ extension TextFieldChecks on Subject<TextField> {
 extension TextStyleChecks on Subject<TextStyle> {
   Subject<bool> get inherit => has((t) => t.inherit, 'inherit');
   Subject<FontWeight?> get fontWeight => has((t) => t.fontWeight, 'fontWeight');
+  Subject<double?> get letterSpacing => has((t) => t.letterSpacing, 'letterSpacing');
   Subject<List<FontVariation>?> get fontVariations => has((t) => t.fontVariations, 'fontVariations');
   Subject<String?> get fontFamily => has((t) => t.fontFamily, 'fontFamily');
   Subject<List<String>?> get fontFamilyFallback => has((t) => t.fontFamilyFallback, 'fontFamilyFallback');
diff --git a/test/widgets/text_test.dart b/test/widgets/text_test.dart
index e8c98481ed7..c522d8097a0 100644
--- a/test/widgets/text_test.dart
+++ b/test/widgets/text_test.dart
@@ -47,6 +47,13 @@ void main() {
       });
     }
 
+    testWidgets('zero letter spacing', (tester) async {
+      check(await getZulipTypography(tester, platformRequestsBold: false))
+        ..englishLike.bodyMedium.isNotNull().letterSpacing.equals(0)
+        ..dense.bodyMedium.isNotNull().letterSpacing.equals(0)
+        ..tall.bodyMedium.isNotNull().letterSpacing.equals(0);
+    });
+
     test('Typography has the assumed fields', () {
       check(Typography().toDiagnosticsNode().getProperties().map((n) => n.name).toList())
         .unorderedEquals(['black', 'white', 'englishLike', 'dense', 'tall']);