trackoffical_app/lib/widget/app_top_bar.dart

import 'package:flutter/material.dart';
import 'package:get/get.dart';

class AppTopBar extends StatelessWidget implements PreferredSizeWidget {
  final Widget? title;
  final List<Widget>? actions;
  final double? toolbarHeight;
  final PreferredSizeWidget? bottom;
  final bool? automaticallyImplyLeading;
  final int? alpha;
  final Widget? leading;
  final bool? centerTitle;

  AppTopBar(
      {super.key,
      required this.title,
      this.actions,
      this.toolbarHeight,
      this.bottom,
      this.automaticallyImplyLeading,
      this.alpha,
      this.leading, this.centerTitle,
      })
      : preferredSize =
            _PreferredAppBarSize(toolbarHeight, bottom?.preferredSize.height);

  @override
  Widget build(BuildContext context) {
    List<Widget> newActions = [];
    final actions = this.actions;
    if (actions != null) {
      for (var one in actions) {
        newActions.add(one);
      }
    }

    return Container(
      decoration: BoxDecoration(
          gradient: LinearGradient(colors: [
        context.theme.colorScheme.secondary.withAlpha(alpha ?? 255),
        context.theme.colorScheme.onSecondaryContainer.withAlpha(alpha ?? 255),
      ])),
      child: AppBar(
        title: title,
        centerTitle: centerTitle??true,
        actions: newActions,
        toolbarHeight: toolbarHeight,
        bottom: bottom,
        backgroundColor: Colors.transparent,
        foregroundColor: Colors.white,
        titleTextStyle: const TextStyle(fontSize: 19.6),
        automaticallyImplyLeading: automaticallyImplyLeading ?? false,
        leading: leading,
      ),
    );
  }

  @override
  final Size preferredSize;
}

class _PreferredAppBarSize extends Size {
  _PreferredAppBarSize(this.toolbarHeight, this.bottomHeight)
      : super.fromHeight(
            (toolbarHeight ?? kToolbarHeight) + (bottomHeight ?? 0));

  final double? toolbarHeight;
  final double? bottomHeight;
}