Add footer to CupertinoFormSection and fix CupertinoFormSection margins. (#72046)

packages/flutter/lib/src/cupertino/form_row.dart

@@ -10,7 +10,7 @@ import 'theme.dart';
 
 // Content padding determined via SwiftUI's `Form` view in the iOS 14.2 SDK.
 const EdgeInsetsGeometry _kDefaultPadding =
-    EdgeInsetsDirectional.fromSTEB(16.0, 6.0, 6.0, 6.0);
+    EdgeInsetsDirectional.fromSTEB(20.0, 6.0, 6.0, 6.0);
 
 /// An iOS-style form row.
 ///
@@ -149,22 +149,7 @@ class CupertinoFormRow extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final CupertinoThemeData themeData = CupertinoTheme.of(context);
-    final TextStyle textStyle = themeData.textTheme.textStyle;
-
-    final List<Widget> rowChildren = <Widget>[
-      if (prefix != null)
-        DefaultTextStyle(
-          style: textStyle,
-          child: prefix!,
-        ),
-      Flexible(
-        child: Align(
-          alignment: AlignmentDirectional.centerEnd,
-          child: child,
-        ),
-      ),
-    ];
+    final TextStyle textStyle = CupertinoTheme.of(context).textTheme.textStyle;
 
     return Padding(
       padding: padding ?? _kDefaultPadding,
@@ -172,7 +157,19 @@ class CupertinoFormRow extends StatelessWidget {
         children: <Widget>[
           Row(
             mainAxisAlignment: MainAxisAlignment.spaceBetween,
-            children: rowChildren,
+            children: <Widget>[
+              if (prefix != null)
+                DefaultTextStyle(
+                  style: textStyle,
+                  child: prefix!,
+                ),
+              Flexible(
+                child: Align(
+                  alignment: AlignmentDirectional.centerEnd,
+                  child: child,
+                ),
+              ),
+            ],
           ),
           if (helper != null)
             Align(

packages/flutter/lib/src/cupertino/form_section.dart

@@ -9,12 +9,16 @@ import 'colors.dart';
 
 // Standard header margin, determined from SwiftUI's Forms in iOS 14.2 SDK.
 const EdgeInsetsDirectional _kDefaultHeaderMargin =
-    EdgeInsetsDirectional.fromSTEB(16.5, 16.0, 16.5, 10.0);
+    EdgeInsetsDirectional.fromSTEB(20.0, 16.0, 20.0, 10.0);
+
+// Standard footer margin, determined from SwiftUI's Forms in iOS 14.2 SDK.
+const EdgeInsetsDirectional _kDefaultFooterMargin =
+    EdgeInsetsDirectional.fromSTEB(20.0, 0.0, 20.0, 10.0);
 
 // Used for iOS "Inset Grouped" margin, determined from SwiftUI's Forms in
 // iOS 14.2 SDK.
 const EdgeInsetsDirectional _kDefaultInsetGroupedRowsMargin =
-    EdgeInsetsDirectional.fromSTEB(16.5, 0.0, 16.5, 16.5);
+    EdgeInsetsDirectional.fromSTEB(20.0, 0.0, 20.0, 10.0);
 
 // Used for iOS "Inset Grouped" border radius, estimated from SwiftUI's Forms in
 // iOS 14.2 SDK.
@@ -39,6 +43,9 @@ enum _CupertinoFormSectionType { base, insetGrouped }
 /// The [header] parameter sets the form section header. The section header lies
 /// above the [children] rows, with margins that match the iOS style.
 ///
+/// The [footer] parameter sets the form section footer. The section footer
+/// lies below the [children] rows.
+///
 /// The [children] parameter is required and sets the list of rows shown in
 /// the section. The [children] parameter takes a list, as opposed to a more
 /// efficient builder function that lazy builds, because forms are intended to
@@ -69,6 +76,9 @@ class CupertinoFormSection extends StatelessWidget {
   /// The [header] parameter sets the form section header. The section header
   /// lies above the [children] rows, with margins that match the iOS style.
   ///
+  /// The [footer] parameter sets the form section footer. The section footer
+  /// lies below the [children] rows.
+  ///
   /// The [children] parameter is required and sets the list of rows shown in
   /// the section. The [children] parameter takes a list, as opposed to a more
   /// efficient builder function that lazy builds, because forms are intended to
@@ -93,6 +103,7 @@ class CupertinoFormSection extends StatelessWidget {
     Key? key,
     required this.children,
     this.header,
+    this.footer,
     this.margin = EdgeInsets.zero,
     this.backgroundColor = CupertinoColors.systemGroupedBackground,
     this.decoration,
@@ -111,6 +122,9 @@ class CupertinoFormSection extends StatelessWidget {
   /// The [header] parameter sets the form section header. The section header
   /// lies above the [children] rows, with margins that match the iOS style.
   ///
+  /// The [footer] parameter sets the form section footer. The section footer
+  /// lies below the [children] rows.
+  ///
   /// The [children] parameter is required and sets the list of rows shown in
   /// the section. The [children] parameter takes a list, as opposed to a more
   /// efficient builder function that lazy builds, because forms are intended to
@@ -136,6 +150,7 @@ class CupertinoFormSection extends StatelessWidget {
     Key? key,
     required this.children,
     this.header,
+    this.footer,
     this.margin = _kDefaultInsetGroupedRowsMargin,
     this.backgroundColor = CupertinoColors.systemGroupedBackground,
     this.decoration,
@@ -150,6 +165,10 @@ class CupertinoFormSection extends StatelessWidget {
   /// [children] rows.
   final Widget? header;
 
+  /// Sets the form section footer. The section footer lies below the
+  /// [children] rows.
+  final Widget? footer;
+
   /// Margin around the content area of the section encapsulating [children].
   ///
   /// Defaults to zero padding if constructed with standard
@@ -228,6 +247,16 @@ class CupertinoFormSection extends StatelessWidget {
       childrenWithDividers.add(longDivider);
     }
 
+    final BorderRadius childrenGroupBorderRadius;
+    switch (_type) {
+      case _CupertinoFormSectionType.insetGrouped:
+        childrenGroupBorderRadius = _kDefaultInsetGroupedBorderRadius;
+        break;
+      case _CupertinoFormSectionType.base:
+        childrenGroupBorderRadius = BorderRadius.zero;
+        break;
+    }
+
     // Refactored the decorate children group in one place to avoid repeating it
     // twice down bellow in the returned widget.
     final DecoratedBox decoratedChildrenGroup = DecoratedBox(
@@ -237,7 +266,7 @@ class CupertinoFormSection extends StatelessWidget {
                 decoration?.color ??
                     CupertinoColors.secondarySystemGroupedBackground,
                 context),
-            borderRadius: _kDefaultInsetGroupedBorderRadius,
+            borderRadius: childrenGroupBorderRadius,
           ),
       child: Column(
         children: childrenWithDividers,
@@ -250,31 +279,43 @@ class CupertinoFormSection extends StatelessWidget {
       ),
       child: Column(
         children: <Widget>[
-          Align(
-            alignment: AlignmentDirectional.centerStart,
-            child: header == null
-                ? null
-                : DefaultTextStyle(
-                    style: TextStyle(
-                      fontSize: 13.5,
-                      color:
-                          CupertinoColors.secondaryLabel.resolveFrom(context),
-                    ),
-                    child: Padding(
-                      padding: _kDefaultHeaderMargin,
-                      child: header!,
-                    ),
-                  ),
-          ),
+          if (header != null)
+            Align(
+              alignment: AlignmentDirectional.centerStart,
+              child: DefaultTextStyle(
+                style: TextStyle(
+                  fontSize: 13.0,
+                  color: CupertinoColors.secondaryLabel.resolveFrom(context),
+                ),
+                child: Padding(
+                  padding: _kDefaultHeaderMargin,
+                  child: header!,
+                ),
+              ),
+            ),
           Padding(
             padding: margin,
             child: clipBehavior == Clip.none
                 ? decoratedChildrenGroup
                 : ClipRRect(
-                    borderRadius: _kDefaultInsetGroupedBorderRadius,
+                    borderRadius: childrenGroupBorderRadius,
                     clipBehavior: clipBehavior,
                     child: decoratedChildrenGroup),
           ),
+          if (footer != null)
+            Align(
+              alignment: AlignmentDirectional.centerStart,
+              child: DefaultTextStyle(
+                style: TextStyle(
+                  fontSize: 13.0,
+                  color: CupertinoColors.secondaryLabel.resolveFrom(context),
+                ),
+                child: Padding(
+                  padding: _kDefaultFooterMargin,
+                  child: footer!,
+                ),
+              ),
+            ),
         ],
       ),
     );

packages/flutter/test/cupertino/form_section_test.dart

@@ -8,20 +8,33 @@ import 'package:flutter/rendering.dart';
 
 void main() {
   testWidgets('Shows header', (WidgetTester tester) async {
-    const Widget header = Text('Enter Value');
+    await tester.pumpWidget(
+      CupertinoApp(
+        home: Center(
+          child: CupertinoFormSection(
+            header: const Text('Header'),
+            children: <Widget>[CupertinoTextFormFieldRow()],
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Header'), findsOneWidget);
+  });
 
+  testWidgets('Shows footer', (WidgetTester tester) async {
     await tester.pumpWidget(
       CupertinoApp(
         home: Center(
           child: CupertinoFormSection(
-            header: header,
+            footer: const Text('Footer'),
             children: <Widget>[CupertinoTextFormFieldRow()],
           ),
         ),
       ),
     );
 
-    expect(header, tester.widget(find.byType(Text)));
+    expect(find.text('Footer'), findsOneWidget);
   });
 
   testWidgets('Shows long dividers in edge-to-edge section part 1',