Refactor backdrop.dart

lib/app_bar.dart

@@ -0,0 +1,184 @@
+import 'package:backdrop/button.dart';
+import 'package:flutter/material.dart';
+
+/// Deprecated. Not needed anymore when [BackdropAppBar] is used.
+///
+/// This enum is used to specify where [BackdropToggleButton] should appear
+/// within [AppBar].
+@Deprecated("Replace by the use of BackdropAppBar."
+    "This feature was deprecated after v0.2.17.")
+enum BackdropIconPosition {
+  /// Indicates that [BackdropToggleButton] should not appear at all.
+  none,
+
+  /// Indicates that [BackdropToggleButton] should appear at the start of
+  /// [AppBar].
+  leading,
+
+  /// Indicates that [BackdropToggleButton] should appear as an action within
+  /// [AppBar.actions].
+  action
+}
+
+/// A material app bar that offers functionality for triggering the
+/// [BackdropScaffold]'s functionality. It is internally implemented using the
+/// [AppBar] class.
+///
+/// What differs from the [AppBar] implementation is the behaviour of
+/// [BackdropScaffold.leading] and [BackdropScaffold.automaticallyImplyLeading].
+///
+/// Usage example:
+/// ```dart
+/// Widget build(BuildContext context) {
+///   return MaterialApp(
+///     title: 'Backdrop Demo',
+///     home: BackdropScaffold(
+///       appBar: BackdropAppBar(
+///         title: Text("Backdrop Example"),
+///         actions: <Widget>[
+///           BackdropToggleButton(
+///             icon: AnimatedIcons.list_view,
+///           )
+///         ],
+///       ),
+///       ...
+///     ),
+///   );
+/// }
+/// ```
+///
+/// See also:
+///  * [AppBar], which is the plain app bar used in material apps.
+class BackdropAppBar extends StatelessWidget implements PreferredSizeWidget {
+  /// See [AppBar.leading].
+  ///
+  /// If this is `null` and if [BackdropAppBar.automaticallyImplyLeading] is
+  /// set to `true`, [BackdropAppBar] sets the underlying [AppBar.leading] to
+  /// [BackdropToggleButton].
+  final Widget leading;
+
+  /// See [AppBar.automaticallyImplyLeading].
+  ///
+  /// If this is set to `true` and [BackdropAppBar.leading] is set to `null`,
+  /// [BackdropAppBar] automatically sets the underlying [AppBar.leading]
+  /// to [BackdropToggleButton].
+  ///
+  /// Defaults to `true`.
+  final bool automaticallyImplyLeading;
+
+  /// The widget that should be displayed as the [AppBar] title.
+  final Widget title;
+
+  /// See [AppBar.actions].
+  final List<Widget> actions;
+
+  /// See [AppBar.flexibleSpace].
+  final Widget flexibleSpace;
+
+  /// See [AppBar.bottom].
+  final PreferredSizeWidget bottom;
+
+  /// See [AppBar.elevation].
+  ///
+  /// Defaults to 0.0. This differs from [AppBar.elevation].
+  final double elevation;
+
+  /// See [AppBar.shape]
+  final ShapeBorder shape;
+
+  /// See [AppBar.backgroundColor].
+  final Color backgroundColor;
+
+  /// See [AppBar.brightness].
+  final Brightness brightness;
+
+  /// See [AppBar.iconTheme].
+  final IconThemeData iconTheme;
+
+  /// See [AppBar.actionsIconTheme].
+  final IconThemeData actionsIconTheme;
+
+  /// See [AppBar.textTheme].
+  final TextTheme textTheme;
+
+  /// See [AppBar.primary].
+  final bool primary;
+
+  /// See [AppBar.centerTitle].
+  final bool centerTitle;
+
+  /// See [AppBar.excludeHeaderSemantics].
+  final bool excludeHeaderSemantics;
+
+  /// See [AppBar.iconTheme].titleSpacing
+  final double titleSpacing;
+
+  /// See [AppBar.toolbarOpacity].
+  final double toolbarOpacity;
+
+  /// See [AppBar.bottomOpacity].
+  final double bottomOpacity;
+
+  /// See [AppBar.preferredSize].
+  @override
+  final Size preferredSize;
+
+  /// Creates a backdrop app bar.
+  ///
+  /// For more information see [AppBar].
+  BackdropAppBar({
+    Key key,
+    this.leading,
+    this.automaticallyImplyLeading = true,
+    this.title,
+    this.actions,
+    this.flexibleSpace,
+    this.bottom,
+    this.elevation = 0.0,
+    this.shape,
+    this.backgroundColor,
+    this.brightness,
+    this.iconTheme,
+    this.actionsIconTheme,
+    this.textTheme,
+    this.primary = true,
+    this.centerTitle,
+    this.excludeHeaderSemantics = false,
+    this.titleSpacing = NavigationToolbar.kMiddleSpacing,
+    this.toolbarOpacity = 1.0,
+    this.bottomOpacity = 1.0,
+  })  : assert(automaticallyImplyLeading != null),
+        assert(elevation == null || elevation >= 0.0),
+        assert(primary != null),
+        assert(titleSpacing != null),
+        assert(toolbarOpacity != null),
+        assert(bottomOpacity != null),
+        preferredSize = Size.fromHeight(
+            kToolbarHeight + (bottom?.preferredSize?.height ?? 0.0)),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return AppBar(
+      leading: leading ??
+          (automaticallyImplyLeading ? BackdropToggleButton() : null),
+      title: title,
+      actions: actions,
+      flexibleSpace: flexibleSpace,
+      bottom: bottom,
+      elevation: elevation,
+      shape: shape,
+      backgroundColor: backgroundColor,
+      brightness: brightness,
+      iconTheme: iconTheme,
+      actionsIconTheme: actionsIconTheme,
+      textTheme: textTheme,
+      primary: primary,
+      centerTitle: centerTitle,
+      excludeHeaderSemantics: excludeHeaderSemantics,
+      titleSpacing: titleSpacing,
+      toolbarOpacity: toolbarOpacity,
+      bottomOpacity: bottomOpacity,
+    );
+  }
+}