Upgrading samples to flutter_lints, part 1 of n (#804)

experimental/desktop_photo_search/lib/src/widgets/about_dialog.dart

@@ -7,8 +7,8 @@ import 'package:flutter/material.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
 
 class PolicyDialog extends StatelessWidget {
-  PolicyDialog({
-    Key key,
+  const PolicyDialog({
+    Key? key,
     this.radius = 8,
   }) : super(key: key);
 
@@ -23,7 +23,7 @@ class PolicyDialog extends StatelessWidget {
         builder: (context) {
           var height = MediaQuery.of(context).size.height;
           var width = MediaQuery.of(context).size.width;
-          return Container(
+          return SizedBox(
             height: height / 4,
             width: width / 4,
             child: Column(
@@ -41,16 +41,16 @@ class PolicyDialog extends StatelessWidget {
                   textAlign: TextAlign.left,
                   text: TextSpan(
                     text: '• ',
-                    style: TextStyle(color: Colors.black, fontSize: 18),
+                    style: const TextStyle(color: Colors.black, fontSize: 18),
                     children: <TextSpan>[
                       TextSpan(
                         text: 'https://policies.google.com/terms',
-                        style: TextStyle(
+                        style: const TextStyle(
                             fontWeight: FontWeight.bold,
                             color: Colors.lightBlue),
                         recognizer: TapGestureRecognizer()
                           ..onTap = () async {
-                            final url = 'https://policies.google.com/terms';
+                            const url = 'https://policies.google.com/terms';
                             if (await url_launcher.canLaunch(url)) {
                               await url_launcher.launch(url);
                             }
@@ -63,16 +63,16 @@ class PolicyDialog extends StatelessWidget {
                   textAlign: TextAlign.left,
                   text: TextSpan(
                     text: '• ',
-                    style: TextStyle(color: Colors.black, fontSize: 18),
+                    style: const TextStyle(color: Colors.black, fontSize: 18),
                     children: <TextSpan>[
                       TextSpan(
                         text: 'https://unsplash.com/terms',
-                        style: TextStyle(
+                        style: const TextStyle(
                             fontWeight: FontWeight.bold,
                             color: Colors.lightBlue),
                         recognizer: TapGestureRecognizer()
                           ..onTap = () async {
-                            final url = 'https://unsplash.com/terms';
+                            const url = 'https://unsplash.com/terms';
                             if (await url_launcher.canLaunch(url)) {
                               await url_launcher.launch(url);
                             }
@@ -93,7 +93,7 @@ class PolicyDialog extends StatelessWidget {
           },
           child: Text(
             'CLOSE'.toUpperCase(),
-            style: TextStyle(fontSize: 20),
+            style: const TextStyle(fontSize: 20),
           ),
         ),
       ],

experimental/desktop_photo_search/lib/src/widgets/photo_details.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
-import 'package:meta/meta.dart';
 import 'package:transparent_image/transparent_image.dart';
 import 'package:url_launcher/link.dart';
 
@@ -17,8 +16,8 @@ typedef PhotoDetailsPhotoSaveCallback = void Function(Photo);
 
 class PhotoDetails extends StatefulWidget {
   const PhotoDetails({
-    @required this.photo,
-    @required this.onPhotoSave,
+    required this.photo,
+    required this.onPhotoSave,
   });
   final Photo photo;
   final PhotoDetailsPhotoSaveCallback onPhotoSave;
@@ -32,21 +31,21 @@ class _PhotoDetailsState extends State<PhotoDetails>
   Widget _buildPhotoAttribution(BuildContext context) {
     return Row(
       children: [
-        Text('Photo by '),
+        const Text('Photo by '),
         Link(
           uri: Uri.parse(
-              'https://unsplash.com/@${widget.photo.user.username}?utm_source=$unsplashAppName&utm_medium=referral'),
+              'https://unsplash.com/@${widget.photo.user!.username}?utm_source=$unsplashAppName&utm_medium=referral'),
           builder: (context, followLink) => TextButton(
             onPressed: followLink,
-            child: Text(widget.photo.user.name),
+            child: Text(widget.photo.user!.name),
           ),
         ),
-        Text(' on '),
+        const Text(' on '),
         Link(
           uri: _unsplashHomepage,
           builder: (context, followLink) => TextButton(
             onPressed: followLink,
-            child: Text('Unsplash'),
+            child: const Text('Unsplash'),
           ),
         ),
       ],
@@ -65,22 +64,22 @@ class _PhotoDetailsState extends State<PhotoDetails>
               const SizedBox(height: 16),
               Card(
                 shape: ContinuousRectangleBorder(
-                  side: BorderSide(color: Colors.black12),
+                  side: const BorderSide(color: Colors.black12),
                   borderRadius: BorderRadius.circular(4),
                 ),
                 child: AnimatedSize(
                   vsync: this,
-                  duration: Duration(milliseconds: 750),
+                  duration: const Duration(milliseconds: 750),
                   child: Padding(
                     padding: const EdgeInsets.fromLTRB(16, 16, 16, 40),
                     child: ConstrainedBox(
-                      constraints: BoxConstraints(
+                      constraints: const BoxConstraints(
                         minWidth: 400,
                         minHeight: 400,
                       ),
                       child: FadeInImage.memoryNetwork(
                         placeholder: kTransparentImage,
-                        image: widget.photo.urls.small,
+                        image: widget.photo.urls!.small!,
                       ),
                     ),
                   ),
@@ -97,7 +96,7 @@ class _PhotoDetailsState extends State<PhotoDetails>
                     const SizedBox(width: 8),
                     IconButton(
                       visualDensity: VisualDensity.compact,
-                      icon: Icon(Icons.cloud_download),
+                      icon: const Icon(Icons.cloud_download),
                       onPressed: () => widget.onPhotoSave(widget.photo),
                     ),
                   ],

experimental/desktop_photo_search/lib/src/widgets/split.dart

@@ -24,15 +24,12 @@ import 'package:flutter/material.dart';
 class Split extends StatefulWidget {
   /// Builds a split oriented along [axis].
   const Split({
-    Key key,
-    @required this.axis,
-    @required this.firstChild,
-    @required this.secondChild,
-    double initialFirstFraction,
+    Key? key,
+    required this.axis,
+    required this.firstChild,
+    required this.secondChild,
+    double? initialFirstFraction,
   })  : initialFirstFraction = initialFirstFraction ?? 0.5,
-        assert(axis != null),
-        assert(firstChild != null),
-        assert(secondChild != null),
         super(key: key);
 
   /// The main axis the children will lay out on.
@@ -81,7 +78,7 @@ class Split extends StatefulWidget {
 }
 
 class _SplitState extends State<Split> {
-  double firstFraction;
+  late double firstFraction;
 
   double get secondFraction => 1 - firstFraction;
 
@@ -111,9 +108,8 @@ class _SplitState extends State<Split> {
     var secondSize = axisSize * secondFraction;
 
     // Clamp the sizes to be sure there is enough space for the dividers.
-    firstSize = firstSize.clamp(halfDivider, axisSize - halfDivider) as double;
-    secondSize =
-        secondSize.clamp(halfDivider, axisSize - halfDivider) as double;
+    firstSize = firstSize.clamp(halfDivider, axisSize - halfDivider);
+    secondSize = secondSize.clamp(halfDivider, axisSize - halfDivider);
 
     // Remove space from each child to place the divider in the middle.
     firstSize = firstSize - halfDivider;
@@ -126,7 +122,7 @@ class _SplitState extends State<Split> {
         // Update the fraction of space consumed by the children,
         // being sure not to allocate any negative space.
         firstFraction += fractionalDelta;
-        firstFraction = firstFraction.clamp(0.0, 1.0) as double;
+        firstFraction = firstFraction.clamp(0.0, 1.0);
       });
     }