Getting rid of containers

packages/flutter/lib/src/material/about.dart

@@ -590,7 +590,7 @@ class _PackagesViewState extends State<_PackagesView> {
                       child: Material(
                         color: Theme.of(context).cardColor,
                         elevation: 4.0,
-                        child: Container(
+                        child: ConstrainedBox(
                           constraints: BoxConstraints.loose(const Size.fromWidth(600.0)),
                           child: _packagesList(context, selectedId, snapshot.data!, widget.isLateral),
                         ),
@@ -887,7 +887,7 @@ class _PackageLicensePageState extends State<_PackageLicensePage> {
           child: Material(
             color: theme.cardColor,
             elevation: 4.0,
-            child: Container(
+            child: ConstrainedBox(
               constraints: BoxConstraints.loose(const Size.fromWidth(600.0)),
               child: Localizations.override(
                 locale: const Locale('en', 'US'),
@@ -1365,13 +1365,15 @@ class _MasterDetailScaffoldState extends State<_MasterDetailScaffold>
                     constraints: BoxConstraints.tightFor(width: masterViewWidth),
                     child: IconTheme(
                       data: Theme.of(context).primaryIconTheme,
-                      child: Container(
-                        alignment: AlignmentDirectional.centerEnd,
+                      child: Padding(
                         padding: const EdgeInsets.all(8),
-                        child: OverflowBar(
-                          spacing: 8,
-                          overflowAlignment: OverflowBarAlignment.end,
-                          children: widget.actionBuilder!(context, _ActionLevel.view),
+                        child: Align(
+                          alignment: AlignmentDirectional.centerEnd,
+                          child: OverflowBar(
+                            spacing: 8,
+                            overflowAlignment: OverflowBarAlignment.end,
+                            children: widget.actionBuilder!(context, _ActionLevel.view),
+                          ),
                         ),
                       ),
                     ),
@@ -1405,7 +1407,7 @@ class _MasterDetailScaffoldState extends State<_MasterDetailScaffold>
                       child,
                     ),
                   duration: const Duration(milliseconds: 500),
-                  child: Container(
+                  child: ConstrainedBox(
                     key: ValueKey<Object?>(value ?? widget.initialArguments),
                     constraints: const BoxConstraints.expand(),
                     child: _DetailView(

packages/flutter/lib/src/material/banner.dart

@@ -345,14 +345,18 @@ class _MaterialBannerState extends State<MaterialBanner> {
         ?? bannerTheme.leadingPadding
         ?? const EdgeInsetsDirectional.only(end: 16.0);
 
-    final Widget actionsBar = Container(
-      alignment: AlignmentDirectional.centerEnd,
+    final Widget actionsBar = ConstrainedBox(
       constraints: const BoxConstraints(minHeight: 52.0),
-      padding: const EdgeInsets.symmetric(horizontal: 8),
-      child: OverflowBar(
-        overflowAlignment: widget.overflowAlignment,
-        spacing: 8,
-        children: widget.actions,
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 8),
+        child: Align(
+          alignment: AlignmentDirectional.centerEnd,
+          child: OverflowBar(
+            overflowAlignment: widget.overflowAlignment,
+            spacing: 8,
+            children: widget.actions,
+          ),
+        ),
       ),
     );
 
@@ -373,8 +377,8 @@ class _MaterialBannerState extends State<MaterialBanner> {
         ?? bannerTheme.contentTextStyle
         ?? defaults.contentTextStyle;
 
-    Widget materialBanner = Container(
-      margin: margin,
+    Widget materialBanner = Padding(
+      padding: margin,
       child: Material(
         elevation: elevation,
         color: backgroundColor,

packages/flutter/lib/src/material/bottom_navigation_bar.dart

@@ -784,7 +784,7 @@ class _Label extends StatelessWidget {
     text = Align(
       alignment: Alignment.bottomCenter,
       heightFactor: 1.0,
-      child: Container(child: text),
+      child: text,
     );
 
     if (item.label != null) {

packages/flutter/lib/src/material/button.dart

@@ -391,7 +391,7 @@ class _RawMaterialButtonState extends State<RawMaterialButton> with MaterialStat
           mouseCursor: effectiveMouseCursor,
           child: IconTheme.merge(
             data: IconThemeData(color: effectiveTextColor),
-            child: Container(
+            child: Padding(
               padding: padding,
               child: Center(
                 widthFactor: 1.0,

packages/flutter/lib/src/material/button_bar.dart

@@ -244,11 +244,12 @@ class ButtonBar extends StatelessWidget {
           child: child,
         );
       case ButtonBarLayoutBehavior.constrained:
-        return Container(
-          padding: EdgeInsets.symmetric(horizontal: paddingUnit),
+        return ConstrainedBox(
           constraints: const BoxConstraints(minHeight: 52.0),
-          alignment: Alignment.center,
-          child: child,
+          child: Padding(
+            padding: EdgeInsets.symmetric(horizontal: paddingUnit),
+            child: Center(child: child),
+          ),
         );
     }
   }

packages/flutter/lib/src/material/calendar_date_picker.dart

@@ -393,52 +393,54 @@ class _DatePickerModeToggleButtonState extends State<_DatePickerModeToggleButton
     final TextTheme textTheme = Theme.of(context).textTheme;
     final Color controlColor = colorScheme.onSurface.withOpacity(0.60);
 
-    return Container(
-      padding: const EdgeInsetsDirectional.only(start: 16, end: 4),
+    return SizedBox(
       height: _subHeaderHeight,
-      child: Row(
-        children: <Widget>[
-          Flexible(
-            child: Semantics(
-              label: MaterialLocalizations.of(context).selectYearSemanticsLabel,
-              excludeSemantics: true,
-              button: true,
-              container: true,
-              child: SizedBox(
-                height: _subHeaderHeight,
-                child: InkWell(
-                  onTap: widget.onTitlePressed,
-                  child: Padding(
-                    padding: const EdgeInsets.symmetric(horizontal: 8),
-                    child: Row(
-                      children: <Widget>[
-                        Flexible(
-                          child: Text(
-                            widget.title,
-                            overflow: TextOverflow.ellipsis,
-                            style: textTheme.titleSmall?.copyWith(
-                              color: controlColor,
+      child: Padding(
+        padding: const EdgeInsetsDirectional.only(start: 16, end: 4),
+        child: Row(
+          children: <Widget>[
+            Flexible(
+              child: Semantics(
+                label: MaterialLocalizations.of(context).selectYearSemanticsLabel,
+                excludeSemantics: true,
+                button: true,
+                container: true,
+                child: SizedBox(
+                  height: _subHeaderHeight,
+                  child: InkWell(
+                    onTap: widget.onTitlePressed,
+                    child: Padding(
+                      padding: const EdgeInsets.symmetric(horizontal: 8),
+                      child: Row(
+                        children: <Widget>[
+                          Flexible(
+                            child: Text(
+                              widget.title,
+                              overflow: TextOverflow.ellipsis,
+                              style: textTheme.titleSmall?.copyWith(
+                                color: controlColor,
+                              ),
                             ),
                           ),
-                        ),
-                        RotationTransition(
-                          turns: _controller,
-                          child: Icon(
-                            Icons.arrow_drop_down,
-                            color: controlColor,
+                          RotationTransition(
+                            turns: _controller,
+                            child: Icon(
+                              Icons.arrow_drop_down,
+                              color: controlColor,
+                            ),
                           ),
-                        ),
-                      ],
+                        ],
+                      ),
                     ),
                   ),
                 ),
               ),
             ),
-          ),
-          if (widget.mode == DatePickerMode.day)
-            // Give space for the prev/next month buttons that are underneath this row
-            const SizedBox(width: _monthNavButtonsWidth),
-        ],
+            if (widget.mode == DatePickerMode.day)
+              // Give space for the prev/next month buttons that are underneath this row
+              const SizedBox(width: _monthNavButtonsWidth),
+          ],
+        ),
       ),
     );
   }
@@ -755,25 +757,27 @@ class _MonthPickerState extends State<_MonthPicker> {
     return Semantics(
       child: Column(
         children: <Widget>[
-          Container(
-            padding: const EdgeInsetsDirectional.only(start: 16, end: 4),
+          SizedBox(
             height: _subHeaderHeight,
-            child: Row(
-              children: <Widget>[
-                const Spacer(),
-                IconButton(
-                  icon: const Icon(Icons.chevron_left),
-                  color: controlColor,
-                  tooltip: _isDisplayingFirstMonth ? null : _localizations.previousMonthTooltip,
-                  onPressed: _isDisplayingFirstMonth ? null : _handlePreviousMonth,
-                ),
-                IconButton(
-                  icon: const Icon(Icons.chevron_right),
-                  color: controlColor,
-                  tooltip: _isDisplayingLastMonth ? null : _localizations.nextMonthTooltip,
-                  onPressed: _isDisplayingLastMonth ? null : _handleNextMonth,
-                ),
-              ],
+            child: Padding(
+              padding: const EdgeInsetsDirectional.only(start: 16, end: 4),
+              child: Row(
+                children: <Widget>[
+                  const Spacer(),
+                  IconButton(
+                    icon: const Icon(Icons.chevron_left),
+                    color: controlColor,
+                    tooltip: _isDisplayingFirstMonth ? null : _localizations.previousMonthTooltip,
+                    onPressed: _isDisplayingFirstMonth ? null : _handlePreviousMonth,
+                  ),
+                  IconButton(
+                    icon: const Icon(Icons.chevron_right),
+                    color: controlColor,
+                    tooltip: _isDisplayingLastMonth ? null : _localizations.nextMonthTooltip,
+                    onPressed: _isDisplayingLastMonth ? null : _handleNextMonth,
+                  ),
+                ],
+              ),
             ),
           ),
           Expanded(
@@ -954,7 +958,7 @@ class _DayPickerState extends State<_DayPicker> {
     while (day < daysInMonth) {
       day++;
       if (day < 1) {
-        dayItems.add(Container());
+        dayItems.add(const LimitedBox(maxWidth: 0.0, maxHeight: 0.0, child: SizedBox.expand()));
       } else {
         final DateTime dayToBuild = DateTime(year, month, day);
         final bool isDisabled =
@@ -1291,12 +1295,11 @@ class _YearPickerState extends State<YearPicker> {
         decoration: decoration,
         height: decorationHeight,
         width: decorationWidth,
-        child: Center(
-          child: Semantics(
-            selected: isSelected,
-            button: true,
-            child: Text(year.toString(), style: itemStyle),
-          ),
+        alignment: Alignment.center,
+        child: Semantics(
+          selected: isSelected,
+          button: true,
+          child: Text(year.toString(), style: itemStyle),
         ),
       ),
     );

packages/flutter/lib/src/material/card.dart

@@ -224,8 +224,8 @@ class Card extends StatelessWidget {
 
     return Semantics(
       container: semanticContainer,
-      child: Container(
-        margin: margin ?? cardTheme.margin ?? defaults.margin!,
+      child: Padding(
+        padding: margin ?? cardTheme.margin ?? defaults.margin!,
         child: Material(
           type: MaterialType.card,
           color: color ?? cardTheme.color ?? defaults.color,