Pressable veggie cards, new launcher icon, release metadata. (#54)

veggieseasons/lib/widgets/veggie_card.dart

@@ -7,6 +7,74 @@ import 'package:veggieseasons/data/veggie.dart';
 import 'package:veggieseasons/screens/details.dart';
 import 'package:veggieseasons/styles.dart';
 
+/// A Card-like Widget that responds to tap events by animating changes to its
+/// elevation and invoking an optional [onPressed] callback.
+class PressableCard extends StatefulWidget {
+  const PressableCard({
+    @required this.child,
+    this.borderRadius = const BorderRadius.all(Radius.circular(10.0)),
+    this.upElevation = 2.0,
+    this.downElevation = 0.0,
+    this.shadowColor = CupertinoColors.black,
+    this.duration = const Duration(milliseconds: 100),
+    this.onPressed,
+    Key key,
+  })  : assert(child != null),
+        assert(borderRadius != null),
+        assert(upElevation != null),
+        assert(downElevation != null),
+        assert(shadowColor != null),
+        assert(duration != null),
+        super(key: key);
+
+  final VoidCallback onPressed;
+
+  final Widget child;
+
+  final BorderRadius borderRadius;
+
+  final double upElevation;
+
+  final double downElevation;
+
+  final Color shadowColor;
+
+  final Duration duration;
+
+  @override
+  _PressableCardState createState() => _PressableCardState();
+}
+
+class _PressableCardState extends State<PressableCard> {
+  bool cardIsDown = false;
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onTap: () {
+        setState(() => cardIsDown = false);
+        if (widget.onPressed != null) {
+          widget.onPressed();
+        }
+      },
+      onTapDown: (details) => setState(() => cardIsDown = true),
+      onTapCancel: () => setState(() => cardIsDown = false),
+      child: AnimatedPhysicalModel(
+        elevation: cardIsDown ? widget.downElevation : widget.upElevation,
+        borderRadius: widget.borderRadius,
+        shape: BoxShape.rectangle,
+        shadowColor: widget.shadowColor,
+        duration: widget.duration,
+        color: CupertinoColors.lightBackgroundGray,
+        child: ClipRRect(
+          borderRadius: widget.borderRadius,
+          child: widget.child,
+        ),
+      ),
+    );
+  }
+}
+
 class VeggieCard extends StatelessWidget {
   VeggieCard(this.veggie, this.isPreferredCategory);
 
@@ -16,61 +84,52 @@ class VeggieCard extends StatelessWidget {
   /// Whether [veggie] falls into one of user's preferred [VeggieCategory]s
   final bool isPreferredCategory;
 
-  List<Widget> _buildStackChildren() {
-    final widgets = <Widget>[];
-
-    widgets.add(Hero(
-      tag: veggie.id,
-      child: Image.asset(
-        veggie.imageAssetPath,
-        fit: BoxFit.cover,
+  Widget _buildDetails() {
+    return DecoratedBox(
+      decoration: BoxDecoration(
+        color: veggie.accentColor,
       ),
-    ));
-
-    widgets.add(Positioned(
-      bottom: 0.0,
-      left: 0.0,
-      right: 0.0,
-      child: DecoratedBox(
-        decoration: BoxDecoration(
-          color: veggie.accentColor,
-        ),
-        child: Padding(
-          padding: const EdgeInsets.all(16.0),
-          child: Column(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: <Widget>[
-              Text(
-                veggie.name,
-                style: Styles.cardTitleText,
-              ),
-              Text(
-                veggie.shortDescription,
-                style: Styles.cardDescriptionText,
-              ),
-            ],
-          ),
+      child: Padding(
+        padding: const EdgeInsets.all(16.0),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: <Widget>[
+            Text(
+              veggie.name,
+              style: Styles.cardTitleText,
+            ),
+            Text(
+              veggie.shortDescription,
+              style: Styles.cardDescriptionText,
+            ),
+          ],
         ),
       ),
-    ));
-
-    return widgets;
+    );
   }
 
   @override
   Widget build(BuildContext context) {
-    return GestureDetector(
-      onTap: () {
+    return PressableCard(
+      onPressed: () {
         Navigator.of(context).push(CupertinoPageRoute(
           builder: (context) => DetailsScreen(veggie.id),
           fullscreenDialog: true,
         ));
       },
-      child: ClipRRect(
-        borderRadius: BorderRadius.circular(10.0),
-        child: Stack(
-          children: _buildStackChildren(),
-        ),
+      child: Stack(
+        children: [
+          Image.asset(
+            veggie.imageAssetPath,
+            fit: BoxFit.cover,
+          ),
+          Positioned(
+            bottom: 0.0,
+            left: 0.0,
+            right: 0.0,
+            child: _buildDetails(),
+          ),
+        ],
       ),
     );
   }