flutter-sport/lib/widgets/appbar.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:sport/widgets/image.dart';

const titleStyle = TextStyle(
    fontWeight: FontWeight.w600, fontSize: 18.0, color: Color(0xff333333));

Widget buildSliverAppBar(BuildContext context, String title,
    {List<Widget> actions,
      backgroundColor = Colors.white,
      paddingLeading = true,
      useClose = false,
      canBack = true,
      innerBoxIsScrolled = false,
      height = 110.0,
      brightness = -1,
      textStyle = titleStyle,
      whiteBackButton = false,
      pinned = true
    }) {
  return SliverAppBar(
      pinned: pinned,
      brightness: brightness ==-1? null :brightness == 1 ? Brightness.dark : Brightness.light,
      expandedHeight: height,
      backgroundColor: backgroundColor,
      forceElevated: innerBoxIsScrolled,
      titleSpacing: 0,
      elevation: 0,
      leading: useClose
          ? IconButton(
              icon: Image.asset("lib/assets/img/topbar_cancel.png"),
              onPressed: () {
                Navigator.of(context).pop();
              },
            )
          : canBack
              ? IconButton(
                  icon: arrowBack(),
                  onPressed: () {
                    Navigator.of(context).pop();
                  },
                )
              : whiteBackButton
                  ? IconButton(
                      icon:
                          Image.asset("lib/assets/img/topbar_return_white.png"),
                      onPressed: () {
                        Navigator.of(context).pop();
                      },
                    )
                  : Container(),
      actions: actions,
      flexibleSpace: buildFlexibleSpace(title,
          paddingLeading: paddingLeading, textStyle: textStyle));
}

Widget buildFlexibleSpace(
  String title, {
  paddingLeading = true,
  textStyle = titleStyle,
}) {
  return LayoutBuilder(builder: (context, box) {
    final FlexibleSpaceBarSettings settings =
        context.dependOnInheritedWidgetOfExactType<FlexibleSpaceBarSettings>();
    return FlexibleSpaceBar(
      centerTitle: false,
      titlePadding: EdgeInsets.fromLTRB(12.0, 0, 0, 15.0),
      title: paddingLeading
          ? Padding(
              padding: EdgeInsets.only(
                  left: (settings.maxExtent - box.biggest.height) / 3 * 2),
              child: Text(
                title,
                style: textStyle,
              ),
            )
          : Text(
              title,
              style: textStyle,
            ),
    );
  });
}

Widget buildActionButton(String title, VoidCallback onPressed,
    {Color textColor}) {
  return IconButton(
    icon: Text(
      title,
      style: textColor != null
          ? TextStyle(fontSize: 16.0, color: textColor)
          : TextStyle(fontSize: 16),
    ),
    onPressed: onPressed,
  );
}

Widget buildBackButton(BuildContext context) {
  return IconButton(
    icon: arrowBack(),
    onPressed: () {
      Navigator.maybePop(context);
    },
  );
}