Add Gap widget

Author: Jens Becker

README.md

@@ -196,6 +196,8 @@ All features with links to their page in the documentation:
   
     
 - ### Flutter Widgets: 
+    - #### [Gap](https://pub.dev/documentation/fleasy/latest/fleasy/Gap-class.html)
+      A wrapper around `SizedBox` for making consistent gaps. Example: Instead of `SizedBox(width: 4.0)` you can just write `Gap.w4()`.
     - #### [EasyFutureBuilder<T>](https://pub.dev/documentation/fleasy/latest/fleasy/EasyFutureBuilder-class.html)
       A wrapper around `FutureBuilder` which makes it easy to display the various states of fetching data from the given `Future`. See [example](https://github.com/devj3ns/fleasy/blob/main/example/lib/main.dart).
     - #### [EasyStreamBuilder<T>](https://pub.dev/documentation/fleasy/latest/fleasy/EasyStreamBuilder-class.html)

lib/src/widgets/gap.dart

@@ -0,0 +1,85 @@
+import 'package:flutter/material.dart';
+
+/// A wrapper around SizedBox for making consistent gaps.
+///
+/// By using [Gap] instead of [SizedBox] you have to write less code and your UI
+/// looks more consistent because you have a strict set of values to choose from.
+///
+/// Examples:
+/// Gap.w4() = SizedBox(width: 4.0)
+/// Gap.h8() = SizedBox(height: 8.0)
+class Gap extends StatelessWidget {
+  const Gap._({Key? key, required this.width, required this.height})
+      : super(key: key);
+
+  /// A gap with a width of 2
+  const Gap.w2({Key? key})
+      : width = 2,
+        height = 0,
+        super(key: key);
+
+  /// A gap with a width of 4
+  const Gap.w4({Key? key})
+      : width = 4,
+        height = 0,
+        super(key: key);
+
+  /// A gap with a width of 8
+  const Gap.w8({Key? key})
+      : width = 8,
+        height = 0,
+        super(key: key);
+
+  /// A gap with a width of 12
+  const Gap.w12({Key? key})
+      : width = 12,
+        height = 0,
+        super(key: key);
+
+  /// A gap with a width of 16
+  const Gap.w16({Key? key})
+      : width = 16,
+        height = 0,
+        super(key: key);
+
+  /// A gap with a height of 2
+  const Gap.h2({Key? key})
+      : width = 0,
+        height = 2,
+        super(key: key);
+
+  /// A gap with a height of 4
+  const Gap.h4({Key? key})
+      : width = 0,
+        height = 4,
+        super(key: key);
+
+  /// A gap with a height of 8
+  const Gap.h8({Key? key})
+      : width = 0,
+        height = 8,
+        super(key: key);
+
+  /// A gap with a height of 12
+  const Gap.h12({Key? key})
+      : width = 0,
+        height = 12,
+        super(key: key);
+
+  /// A gap with a height of 16
+  const Gap.h16({Key? key})
+      : width = 0,
+        height = 16,
+        super(key: key);
+
+  final double width;
+  final double height;
+
+  @override
+  Widget build(BuildContext context) {
+    return SizedBox(
+      height: height,
+      width: width,
+    );
+  }
+}

lib/src/widgets/widgets.dart

@@ -1,3 +1,4 @@
 export 'easy_future_builder.dart';
 export 'easy_stream_builder.dart';
+export 'gap.dart';
 export 'snapshot_state_info.dart';