flex_color_scheme 1.0.0-dev.2

A Flutter package to make and use beautiful color scheme based MaterialApp themes.

FlexColorScheme

!!PRE-RELEASE VERSION !!

This package is still being worked on, both regarding the API and its documentation.

• API is now about 99% ready.
• Documentation is about 95% ready.
• This is hopefully the last pre-release before 1.0.0 release.

FlexColorScheme helps you make beautiful color scheme based Flutter themes, with optional level of primary color branded surfaces. The created themes are based on the same concept as Flutter's newer ColorScheme based themes, but with a few interesting twists and features.

You can find a blog summary here.

Contents

• Introduction
• Installing
  • Default Sample Application
  • Live WEB Demos of the Examples
• Tutorial
  • The HomePage of all the Examples
  • Example 1 Use a predefined color scheme
  • Example 2 Create a custom color scheme
  • Example 3 Switch between different color schemes
  • Example 4 Switch between all built in color schemes
  • Example 5 Full featured demo
• Behind the scenes
  • Used Theme Customizations
• API Reference

Introduction

A total of 20 different color schemes for both light and dark modes are available as predefined color schemes. These are ready to use nice color schemes, but you can just easily create your own custom color schemes and make themes from them. If you have seen the Flutter FlexFold web demo application, then you have already seen FlexColorScheme in action. The FlexFold demo uses this package for its fancy theming and to enable switching between all the themes effortlessly. The examples in this package show you how it is done.

FlexColorScheme makes a few opinionated, but subtle theme modifications compared to the default Flutter ThemeData.from themes created from a ColorScheme. It also corrects a few minor theme inconsistencies that exist in the current version of Flutter's ThemeData.from factory. These topics are covered in detail in the last chapter.

The Material guide also talks about using color branded surfaces. With FlexColorScheme you can easily create such primary color branded themes. This is done by using four built-in strengths for blending in primary color into surface and background colors, while avoiding blending it in with the scaffold background color, for all but the highest strength.

The scheme colors can like Flutter's standard ColorScheme, be created by specifying all required schemes colors, but you can also specify just the primary color and get all other colors needed for a complete color scheme computed based on just the provided primary color.

When you have defined your FlexColorScheme you make a theme based on it with the toTheme method, that returns a ThemeData object that you can use just like any other ThemeData object. You can of course override this returned theme and add additional custom sub-theming to it with the normal ThemeData copyWith method.

Installing

In the pubspec.yaml of your Flutter project, add the following dependency:

dependencies:
  ...
  flex_color_scheme: any

In your library file add the following import:

import 'package:flex_color_scheme/flex_color_scheme.dart';

You can now start using FlexColorSchemebased themes in your application. The easiest way to do so is to use one of the 20 built-in color schemes. The schemes have enums that you can use to refer to them, their corresponding data object holds name, description and separate scheme data for each schemes' light and dark mode. The Google Material schemes used as example in the Material Guide, that also exist as defaults for ColorScheme.light() and ColorScheme.dark() in Flutter SDK, as well as the high contrast schemes ColorScheme.highContrastLight() and ColorScheme.highContrastDark() in Flutter are also included as the first two predefined schemes in FlexColorScheme.

Default Sample Application

The package contains five different example applications with increasing complexity.

To try the simplest of them, example 1 in FlexColorScheme on a device or simulator, clone the repository and run the example:

cd example/
flutter run --release

The result is a sample app that uses one of the built color schemes as its theme, has a light/dark/system theme mode toggle and includes a theme showcase, so you can see the impact of the theme on common Material widgets.

NOTE:

If you clone the repository to build the samples, then open the package /example folder with your IDE to build the above default example. This example is the same as the example in the /example/lib/example1 folder. If you want to build the other examples, without setting up different configurations in your IDE for the different main files, you can just copy and paste each example's code into the /example/lib/main.dart file to build it. Just correct the relative import of import 'all_shared_imports.dart'; in the copy, and you are ready to go.

Live WEB Demos of the Examples

If you just want to have a quick look at all the example applications, you can try live web versions of them.

Example 1presents the simplest use case, to just use one of the built-in color schemes as your application theme and toggle between its light and dark variant, or allow device mode setting to control if the dark or light theme is used.

Example 2 is like example 1, but here we use custom colors to make a custom scheme and turn it into a theme.

In example 3 we can toggle the active theme between 3 different predefined color schemes, plus the custom one we made in example 2.

In example 4 we can toggle between all the different built in themes.

Example 5 is the last, and most complex one of the examples and presents more configuration options that you can modify interactively. This example is best seen and tested on a tablet, desktop or desktop web browser, rather than on a phone, but it certainly works on a phone sized canvas too. This example is explained in more detail further below.

Flexfold demo
The fanciest example of FlexColorScheme usage is in the Flexfold demo app.

This might look and feel complicated, but it is actually only slightly more fancy than above example nr 5, that uses almost all the same theming features and exactly the same themes as the Flexfold demo app. Just go through the examples, and you will be ready to make cool interactively custom themed apps like the ones in the Flexfold demo app in no time.

Tutorial

Below we will go through the key topics in each of the 5 examples and explain them. For simplicity the example applications do not use any advanced state management solution. The key part to each example is always in the used stateful Material app, where all the scheme setup for the themes are made in these demos. The rest of the content in the examples are just there to make a relevant visual presentation on the resulting theme from the used FlexColorScheme.

The HomePage of all the Examples

The content of the HomePage in all these examples is not really so relevant for using FlexColorScheme based application theming. The critical parts are in the example MaterialApp theme definitions. The HomePage just contains UI to visually show what the defined themes look like when used in an application with commonly used Widgets. It also allows interaction with a few FlexColorScheme APIs in the later examples. All examples include a theme mode switch.

We pass in the FlexSchemeData we used for the active theme to the application's HomePage. This is not really needed in to use FlexColorScheme schemes based themes, but we use it to be able to show the active theme's name and description in the examples. We also use it for the 3-way theme mode switch, that uses the scheme colors in its toggle widget for its custom theme mode option buttons.

The Optional FlexThemeModeSwitch

The only thing on the HomePage that might be of interest is the FlexThemeModeSwitch, which is the UI for the 3-way theme mode toggle switch used in the examples to change theme mode.

Using it is very simple, pass it the selected theme mode, the active FlexSchemeData scheme and check the onThemeModeChanged callback for changes and act on it.

FlexThemeModeSwitch(
  themeMode: themeMode,
  onThemeModeChanged: onThemeModeChanged,
  flexSchemeData: flexSchemeData,
),

Using the FlexThemeModeSwitch 3-way theme mode toggle switch is totally optional and not required to use FlexColorScheme based themes. It is a simple, yet interesting theme mode switch design, it was included on request as a bonus feature in the FlexColorScheme package after being requested after it was seen based on in the Flexfold demo app.

In the Flexfold demo it was originally a fairly fixed design but now FlexThemeModeSwitch has many properties that allows you to customize it extensively, please find its API reference here and its companion, the FlexThemeModeOptionButton API reference here.

You can vary the way it looks, here are some examples that just scratch the surface:

Example 1 Use a predefined color scheme

The first and very simple example shows how you can use a predefined color scheme in FlexColorScheme to define light and dark themes using the scheme, and then switch between the light and dark mode. A theme showcase widget shows the theme with several common Material widgets.

void main() => runApp(const DemoApp());

class DemoApp extends StatefulWidget {
 const DemoApp({Key key}) : super(key: key);
 @override
 _DemoAppState createState() => _DemoAppState();
}

class _DemoAppState extends State<DemoApp> {
 // Used to select if we use the dark or light theme.
 ThemeMode themeMode;

 @override
 void initState() {
   themeMode = ThemeMode.light;
   super.initState();
 }

 @override
 Widget build(BuildContext context) {
   // Define which predefined flex scheme to use.
   // Go ahead and try some other ones too.
   const FlexScheme usedFlexScheme = FlexScheme.mandyRed;
   return MaterialApp(
     debugShowCheckedModeBanner: false,
     title: 'FlexColorScheme',

     // A light scheme, passed to FlexColorScheme.light factory, then use the 
     // toTheme method to return the resulting theme to the MaterialApp theme.
     theme: FlexColorScheme.light(colors: 
       FlexColor.schemes[usedFlexScheme].light).toTheme,
     
     // We do the same thing for the dark theme, but using FlexColorScheme.dark 
     // factory and the dark FlexSchemeColor in FlexColor.schemes.
     darkTheme: FlexColorScheme.dark(colors: 
       FlexColor.schemes[usedFlexScheme].dark).toTheme,
     // Use the above dark or light theme, based on active themeMode 
     // value light/dark/system.
     themeMode: themeMode,
     
     home: HomePage(
       themeMode: themeMode,
       onThemeModeChanged: (ThemeMode mode) {
         setState(() { themeMode = mode; });
       },
       flexSchemeData: FlexColor.schemes[usedFlexScheme],
     ),
   );
 }
}

Building and running example 1

When you build and run example 1 you get a sample application that looks like this in light and dark mode:

Try example 1 live on the web here

Scroll down to see the theme showcase further below, it presents the theme with common Material widgets. This simple first example is not using primary color surface branding, it is just a normal theme with a few convenient fixes for some theme design gaps in Flutter's own themes created with ThemeData.from a ColorScheme.

Example 2 Create a custom color scheme

This example shows how you can define your own FlexSchemeData and create a FlexColorScheme based theme from it. A theme showcase widget shows the theme with several common Material widgets.

The full code is not shown in the tutorial, please see the code in the package folder flex_color_scheme/example/lib/example2 for the entire example.

To make a custom scheme color, let us for simplicity define it as a const in this example. We just need to make a [FlexSchemeData] object with a name, description and scheme colors for the light and matching dark theme. In this example we use dark purple and deep green and matching desaturated versions in dark-mode.

const FlexSchemeData customFlexScheme = FlexSchemeData(
  name: 'Custom purple',
  description: 'Purple theme created from custom defined colors.',
  light: FlexSchemeColor(
    primary: Color(0xFF4E0028),
    primaryVariant: Color(0xFF320019),
    secondary: Color(0xFF003419),
    secondaryVariant: Color(0xFF002411),
  ),
  dark: FlexSchemeColor(
    primary: Color(0xFF9E7389),
    primaryVariant: Color(0xFF775C69),
    secondary: Color(0xFF738F81),
    secondaryVariant: Color(0xFF5C7267),
  ),
);

Then we simply use this customFlexScheme FlexSchemeData instances light and dark properties to pass the appropriate scheme colors to the FlexColorScheme light and dark factory for each theme mode and again use the toTheme getter to get the themes defined by them.

  :
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'FlexColorScheme',
      
      theme: FlexColorScheme.light(colors: customFlexScheme.light).toTheme,
      darkTheme: FlexColorScheme.dark(colors: customFlexScheme.dark).toTheme,
      themeMode: themeMode,
      
      home: HomePage(
        themeMode: themeMode,
        onThemeModeChanged: (ThemeMode mode) {
          setState(() { themeMode = mode; });
        },
        flexSchemeData: customFlexScheme,
      ),
    );
  }
}

When you build and run example 2 you get a sample application that looks like this in light and dark mode:

Try example 2 live on the web here

Scroll down to see the theme showcase widgets further below, presenting the theme with some widgets. This example is not using primary color surface branding, it is just a normal theme with a few convenient fixes for certain theme properties.

Example 3 Switch between different color schemes

This example shows how you can use three built-in color schemes, and add one custom scheme, using all four as selectable FlexColorScheme based theme options in an application. The example also uses strong branded surface colors. A theme showcase widget shows the theme with several common Material widgets.

The full example code is not shown here, please see the code in the package folder flex_color_scheme/example/lib/example3 for the entire example.

The customFlexScheme FlexSchemeData setup is the same as in example 2. In the example below, if we selected the FlexScheme.custom, we use our customFlexScheme object, otherwise the selected built-in scheme we selected on the HomePage. We also set the surface style to FlexSurface.strong, for strong primary branded surfaces.

:
class _DemoAppState extends State<DemoApp> {
  ThemeMode themeMode;
  // Used to store which FlexSchemeData option we selected
  FlexScheme flexScheme;

  @override
  void initState() {
    themeMode = ThemeMode.light;
    flexScheme = FlexScheme.hippieBlue; // Default selected theme
    super.initState();
  }
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'FlexColorScheme',

      theme: FlexColorScheme.light(
        colors: flexScheme == FlexScheme.custom
            ? customFlexScheme.light
            : FlexColor.schemesWithCustom[flexScheme].light,
        surfaceStyle: FlexSurface.strong,
      ).toTheme,

      darkTheme: FlexColorScheme.dark(
        colors: flexScheme == FlexScheme.custom
            ? customFlexScheme.dark
            : FlexColor.schemesWithCustom[flexScheme].dark,
        surfaceStyle: FlexSurface.strong,
      ).toTheme,
      themeMode: themeMode,

      home: HomePage(
        themeMode: themeMode,
        onThemeModeChanged: (ThemeMode mode) {
          setState(() { themeMode = mode; });
        },
        // We pass the enum value of the active scheme to the HomePage.
        flexScheme: flexScheme,
        // Where we can select a new scheme and get its enum value back.
        onFlexSchemeChanged: (FlexScheme selectedScheme) {
          setState(() { flexScheme = selectedScheme; });
        },
        // We take care to pass in selected built-in scheme data 
        // or the custom one we made if it is selected.
        flexSchemeData: flexScheme == FlexScheme.custom
            ? customFlexScheme 
            : FlexColor.schemesWithCustom[flexScheme],
      ),
    );
  }
}

Try example 3 live on the web here

Example 4 Switch between all built in color schemes

This example shows how you can use all the built in color schemes in FlexColorScheme to interactively select which one of the built in schemes is used to define the active theme. The example also uses medium branded background and surface colors. A theme showcase widget shows the theme with several common Material widgets.

The full example code is not shown here, please see the code in the package folder flex_color_scheme/example/lib/example4 for the entire example.

In this example set the surface style to FlexSurface.medium, for medium primary color branded surfaces. The example is straight forward, we use the built in FlexColor.schemesList to access all the pre-defined schemes by list index number that we simple change with popup menu on the HomePage.

:
class _DemoAppState extends State<DemoApp> {
  ThemeMode themeMode;
  // Used to select which FlexSchemeData we use from a popup menu.
  int themeIndex;

  @override
  void initState() {
    themeMode = ThemeMode.light;
    themeIndex = 6; // Start with index 6, the brand blue colors.
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'FlexColorScheme',

      theme: FlexColorScheme.light(
        colors: FlexColor.schemesList[themeIndex].light,
        surfaceStyle: FlexSurface.medium,
      ).toTheme,
      
      darkTheme: FlexColorScheme.dark(
        colors: FlexColor.schemesList[themeIndex].dark,
        surfaceStyle: FlexSurface.medium,
      ).toTheme,

      themeMode: themeMode,
      
      home: HomePage(
        themeMode: themeMode,
        onThemeModeChanged: (ThemeMode mode) {
          setState(() { themeMode = mode; });
        },
        // We can pass the index of the active theme to the HomePage.
        schemeIndex: themeIndex,
        // Where we can select a new theme in a popup menu
        // and get its index back.
        onSchemeChanged: (int index) {
          setState(() { themeIndex = index; });
        },
        flexSchemeData: FlexColor.schemesList[themeIndex],
      ),
    );
  }
}

Try example 4 live on the web here

Example 5 Full featured demo

This example shows how you can use all the built in color schemes in FlexColorScheme to define themes from them and how you can define your own custom scheme colors and use them together with the predefined ones. It can give you an idea of how you can create your own complete custom list of themes if you do not want to use any of the predefined ones.

The example also shows how you can use the surface branding feature and how to use the custom app bar theme features of FlexColorScheme. The usage of the true black theme feature for dark themes is also demonstrated. Using the optional Windows desktop like tooltip theme is also shown.

The example includes a dummy responsive side menu and rail to give a visual presentation of what applications that have larger visible surfaces using the surface branding look like. A theme showcase widget again shows the theme with several common Material widgets.

In this case we also use the laziest option for creating our 2nd custom olive green light and dark theme, we create the FlexSchemeColor with the from factory that only requires the primary color. It still usually manages to create pretty well toned themes from just a single color for each theme mode.

The first scheme we do like in example 2 and 3, but in this case we also define a custom color value for the FlexSchemeColor appBarColor property. The built in color schemes use their secondary variant color as their custom app bar color, it could of course be any color, but for consistency we will do the same in this custom FlexSchemeColor.

The full example code is not shown here, please see the code in the package folder flex_color_scheme/example/lib/example5 for the entire example.

 void main() => runApp(const DemoApp());
 
 // Create a custom flex color scheme for a light theme.
 const FlexSchemeColor myScheme1Light = FlexSchemeColor(
   primary: Color(0xFF4E0028),
   primaryVariant: Color(0xFF320019),
   secondary: Color(0xFF003419),
   secondaryVariant: Color(0xFF002411),
   appBarColor: Color(0xFF002411),
 );
 // Create a corresponding custom flex color scheme for a dark theme.
 const FlexSchemeColor myScheme1Dark = FlexSchemeColor(
   primary: Color(0xFF9E7389),
   primaryVariant: Color(0xFF775C69),
   secondary: Color(0xFF738F81),
   secondaryVariant: Color(0xFF5C7267),
   appBarColor: Color(0xFF5C7267),
 );

Next we will use a shorter convenient way to define a FlexSchemeColor object from just single color. The FlexSchemeColor.from factory can do the trick with just the primary color defined. The custom app bar color will in this case also receive the same color value as the computed one for secondaryVariant color.

 final FlexSchemeColor myScheme2Light =
     FlexSchemeColor.from(primary: const Color(0xFF4C4E06));

 final FlexSchemeColor myScheme2Dark =
     FlexSchemeColor.from(primary: const Color(0xFF9D9E76));

Then we simply create a list with all color schemes we will use, starting with all the built-in ones and then adding our two custom ones at the end.

  final List<FlexSchemeData> myFlexSchemes = <FlexSchemeData>[
   // Add the predefined FlexColor schemes
   ...FlexColor.schemesList,
   // Then add our first custom ones to the list.
   const FlexSchemeData(
     name: 'Custom purple',
     description: 'Purple theme created from custom defined colors.',
     light: myScheme1Light,
     dark: myScheme1Dark,
   ),
   // Do the same for our second custom scheme.
   FlexSchemeData(
     name: 'Custom olive green',
     description: 'Olive green theme created from custom primary color.',
     light: myScheme2Light,
     dark: myScheme2Dark,
   ),
 ];

Now we have list myFlexSchemes with all the built-in themes and our own custom ones, that we can simply use the same way as we did in example 4.

In this example we will also toggle the app bar theme style, the surface primary color branding strength, tooltip style and try the true black theme toggle for dark-mode as well.

We will also use a toggle that allows us to instead of using the FlexColorScheme.toTheme method use the standard flutter ThemeData.from factory to create the theme from the same color scheme definition. This way we can use this toggle to see the differences.

 :
 
 class _DemoAppState extends State<DemoApp> {
   // Used to select if we use the dark or light theme.
   ThemeMode themeMode;
    // Used to select which FlexSchemeData we use in our list of schemes.
   int themeIndex; 
   // Enum used to select what app bar style we use.
   FlexAppBarStyle flexAppBarStyle;
   // Enum used to control primary color surface branding on surface and background.
   FlexSurface flexSurface;
   // If true, tooltip theme background will be light in light theme, and dark
   // in dark themes. The Flutter and Material default and standard is the other
   // way, tooltip background color is inverted compared to app background.
   bool tooltipsMatchBackground;
   // Allow toggling between normal dark mode and true black dark mode.
   bool darkIsTrueBlack;
   // Use the toTheme method to create Themes from [FlexColorScheme]. This
   // is the preferred method when using [FlexColorScheme]. In this demo
   // you can use a toggle to see what a FlexColorScheme looks like if you just
   // use its color scheme and use [ThemeData.from] to instead create the theme.
   bool useToThemeMethod;
 
   @override
   void initState() {
     themeMode = ThemeMode.light;
     themeIndex = 7; // Start with deep blue see theme.
     flexAppBarStyle = FlexAppBarStyle.primary;
     flexSurface = FlexSurface.medium;
     tooltipsMatchBackground = false;
     darkIsTrueBlack = false;
     useToThemeMethod = true;
     super.initState();
   }

We define the light theme for the app, using current theme index, selected surface style and app bar style. With the built in 20 themes and the custom ones we defined above, we can use 22 different app themes via the definition below, times the surface styles and app bar variants.

The factory FlexColorScheme.light is used to define a FlexColorScheme for a light theme, from the light FlexSchemeColor plus some other theme factory properties, like the surface and app bar style used in this example as well as the tooltip and true black setting for the dark theme.

   :
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
       debugShowCheckedModeBanner: false,
       title: 'FlexColorScheme',


       theme: useToThemeMethod
           ? FlexColorScheme.light(
               colors: myFlexSchemes[themeIndex].light,
               surfaceStyle: flexSurface,
               appBarStyle: flexAppBarStyle,
               tooltipsMatchBackground: tooltipsMatchBackground,
             ).toTheme

We also demonstrate how to create the same theme with the standard from color scheme ThemeData factory. The surface style works, but will not be applied as elegantly, but it works fairly OK up to medium branding. The app bar style has no effect, nor the tooltip style. We also have to make sure we use the same typography as the one used in FlexColorScheme, otherwise the animated theme will show an assertion error as it cannot animate between different typography or null default typography in the theme data. When toggling between the standard ThemeData.from and the FlexColorScheme.toTheme we can observe the differences and see some theme colors that the standard method does not adjust to match the used color scheme.

           : ThemeData.from(
               colorScheme: FlexColorScheme.light(
                 colors: myFlexSchemes[themeIndex].light,
                 surfaceStyle: flexSurface,
                 appBarStyle: flexAppBarStyle,
                 tooltipsMatchBackground: tooltipsMatchBackground,
               ).toScheme,
             ).copyWith(
               typography: Typography.material2018(
                 platform: defaultTargetPlatform,
               ),
             ),

We do the equivalent definition for the dark theme, and we add the true black option as well. In dark-mode we can see many gaps in the resulting ThemeData when using the standard ThemeData.from factory to create the theme.

       
       darkTheme: useToThemeMethod
           ? FlexColorScheme.dark(
               colors: myFlexSchemes[themeIndex].dark,
               surfaceStyle: flexSurface,
               appBarStyle: flexAppBarStyle,
               tooltipsMatchBackground: tooltipsMatchBackground,
               darkIsTrueBlack: darkIsTrueBlack,
             ).toTheme
           : ThemeData.from(
               colorScheme: FlexColorScheme.dark(
                 colors: myFlexSchemes[themeIndex].dark,
                 surfaceStyle: flexSurface,
                 appBarStyle: flexAppBarStyle,
                 tooltipsMatchBackground: tooltipsMatchBackground,
                 darkIsTrueBlack: darkIsTrueBlack,
               ).toScheme,
             ).copyWith(
               typography: Typography.material2018(
                 platform: defaultTargetPlatform,
               ),
             ),

The rest of the additions in the stateful MaterialApp are just passing in current values and getting a new value for it via callbacks for all our settings values.

      
// themeMode value and change callback
       themeMode: themeMode,
       home: HomePage(
         themeMode: themeMode,
         onThemeModeChanged: (ThemeMode mode) {
           setState(() { themeMode = mode; });
         },
         // Used theme index and change callback
         schemeIndex: themeIndex,
         onSchemeChanged: (int index) {
           setState(() { themeIndex = index;});
         },
         // Used app bar style and change callback
         appBarStyle: flexAppBarStyle,
         onAppBarStyleChanged: (FlexAppBarStyle style) {
           setState(() { flexAppBarStyle = style; });
         },
         // Used surface branding and change callback
         themeSurface: flexSurface,
         onThemeSurfaceChanged: (FlexSurface surface) {
           setState(() { flexSurface = surface; });
         },
         // Used tooltip style and change callback
         tooltipsMatchBackground: tooltipsMatchBackground,
         onTooltipsMatchBackgroundChanged: (bool value) {
           setState(() { tooltipsMatchBackground = value; });
         },
         // True black mode and change callback
         darkIsTrueBlack: darkIsTrueBlack,
         onDarkIsTrueBlackChanged: (bool value) {
           setState(() { darkIsTrueBlack = value; });
         },
         // Theme creation method and toggle method callback
         useToTheme: useToThemeMethod,
         onUseToThemeChanged: (bool value) {
           setState(() { useToThemeMethod = value; });
         },

         flexSchemeData: myFlexSchemes[themeIndex],
       ),
     );
   }
 }

With this example we include a side rail, it actually expands to menu on web desktop sized canvas and even phone landscape, just for demo purposes. It is there to give us a better idea what a surface branded theme looks like. It is of course best viewed and experienced on a tablet, or the web demo where the surface branding theming effect is more obvious.

Try example 5 live on the web here

Let us now explore the effect of branded surface color in both light and dark mode. Branded surfaces are often associated with dark mode, but it works well with light mode too when applied delicately. Below you see how the primary color gets blended into Material surface and even stronger so, into Material background. The screen shots below are using the medium branding strength.

You can use the toggle in the example to change from standard no branded surfaces colors, to light, medium, strong and heavy.

The scaffold background does not receive any branding until the heavy mode. You might think that this and all the other theming can be done by just passing the same scheme colors to the ThemeData.from factory. That is why this demo allows you to flip a switch to do just that, so you can see and observe the difference between color scheme based themes created by FlexColorScheme.toTheme and ThemeData.from. Feel free to experiment with the live web demo where the differences are even easier to observe since you can have both versions open side by side, in a large browser windows.

Now when we tried the branding, we can test the tricks FlexColorScheme can do with the AppBarTheme. You can easily toggle both dark and light mode app bar theme to use differently themed backgrounds. It can use scheme primary color, the default Material plain white/dark background color, or the primary branded surface and background color versions, as well as an extra custom app bar scheme color, which is a separate scheme color, that does not exist in Flutter's ColorScheme, it thus does not have to be any of the colors in Flutter ColorScheme. The predefined schemes actually use the color defined for normal scheme secondaryVariant as the custom color used for the app bar theme. When you make your own schemes you can do the same or use a totally not scheme related color as the app bar's theme color.

Below you can see some different branding strengths with a background primary color branded app bar color used as well. This example compares medium versus heavy branding. The medium choice is usually well-balanced, but light can be subtle and nice too. If you want to make a bold statement theme, go with heavy. Please note that the visual impact of the branding also depends on how saturated the primary color is.

Here are few more images of the heavy primary color branded version, when looking at some widgets as well.

Dark-mode is nice, but with FlexColorScheme you can go even "deeper", to true black with the flick of a switch. When using the true black option for dark-mode, surface, background and scaffold background are set to fully black. This can save power on OLED screens as the pixels are turned off, but it can also cause scrolling artefact issues when pixels turn fully on and off rapidly as you scroll. You can read about this and see an example of it in the Material design guide as well (scroll back up one heading to get to the mention of it).

If you use branded surfaces with true black mode enabled, you will notice that the branding has less of an impact, only at strong and heavy levels will it have an impact. This is by design, to keep most surface totally or very close to black when true black is combined with surface branding. If you really want total and true black for all surfaces and backgrounds, then avoid combining true black mode with branded surfaces. On the other hand it still makes an even darker theme, than normal dark theme, and it eliminates the scrolling issue since all background colored pixels are not fully off in the strong and heavy branded true black modes.

Here is an example of a branded dark theme with true black OFF and true black ON, when using heavy branding.

Behind the scenes

FlexColorScheme does not actually use the ThemeData.from factory with a passed in ColorScheme to make its theme. It uses the ThemeData factory directly with some custom theming. It does of course define a ColorScheme that is uses for the ThemeData. FlexColorScheme uses color calculations for the primary color brand blended surfaces, and for the lazy schemes that do not specify all colors in a color scheme.

Used Theme Customizations

In addition to the primary color branded surfaces, full shaded schemes from just one primary color, true black and app bar tricks. The returned ThemeData contains some opinionated modifications and theme corrections compared to what you get if you would just use the standard ThemeData.from with a ColorScheme. You can still of course override the returned theme with your own theme modifications and additions, by using the copyWith method on the resulting theme.

If you want the details of what the differences compared to the standard ThemeData.from factory are, here is a complete list:

• ScaffoldBackground has its color own property in FlexColorScheme and can if so desired differ from the ColorScheme background color. In the branding implementation. The scaffoldBackground typically gets no primary branding applied, only in the heavy choice is there a small amount of it. Whereas background in the scheme receives the most color branding of the surface colors. Which fits well for where the background color is used on Material in Widgets, but it does not go so well together with scaffoldBackground, which is the reason why it got its own scheme color value in this implementation.

• The dialogBackgroundColor uses the ColorScheme.surface color instead of the ColorScheme.background because the background color gets the strongest branding when branding is used. This did not look so good on dialogs, so its color choice was changed to surface instead, that gets very light branding applied. With standard default Material surface colors the background and surface colors are the same, so there is no difference in that case.

• The indicatorColor uses color scheme primary instead of the default that is onSurface in dark-mode, and onPrimary in light mode. This is just an opinionated choice.

• For toggleableActiveColor the color scheme secondary color is used. The Flutter default just uses the default ThemeData colors and not the actual colors you define in a color scheme you create your theme from. This is probably not yet corrected, perhaps an oversight? See issue: https://github.com/flutter/flutter/issues/65782.

• Flutter themes created with ThemeData.from does not define any color scheme related color for the primaryColorDark color, this method does. See issue: https://github.com/flutter/flutter/issues/65782. ThemeData.from leaves this color at ThemeData` factory default, this may not match your scheme. Widgets seldom use this color, so the issue is rarely seen.

• Flutter themes created with ThemeData.from does not define any color scheme based color for the primaryColorLight color, this method does. See issue: https://github.com/flutter/flutter/issues/65782. ThemeData.from leaves this color at ThemeData factory default this may not match your scheme. Widgets seldom use this color, so the issue is rarely seen.

• Flutter themes created with ThemeData.from does not define any color scheme based color for the secondaryHeaderColor color, this method does. See issue: https://github.com/flutter/flutter/issues/65782. ThemeData.from leaves this color at ThemeData factory default this may not match your scheme. Widgets seldom use this color, so the issue is rarely seen.

• Background color for AppBarTheme can use a custom colored appbar theme in both light and dark themes that is not dependent on theme primary or surface color. This functionality needs a custom text theme to be possible to implement it without a context. The implementation does however not give correct localized typography.

  A new feature implemented via: https://github.com/flutter/flutter/pull/71184 also enables this kind app bar themes and keep the correct typography localization. This new feature is (as of 13.12.2020) not yet available on channel stable. The first version on master could also not be enabled via Themes only, one also had to opt in on AppBar level, making it difficult to adopt the feature. I wrote a proposal to introduce opt in on theme level too: https://github.com/flutter/flutter/issues/72206 The proposal has already been implemented. When these new features land in stable channel, the implementation below will be changed to use the new AppBarTheme feature, as it is better than this work-around since we no longer need a custom text theme to implement it.

• The AppBarTheme elevation defaults to 0.

• Like standard ThemeData.from color scheme themes, the bottomAppBarColor also uses scheme surface color. Additionally, this color is also applied to BottomAppBarTheme, that like the app bar also gets default elevation 0.

• A deviation from ThemeData.from color scheme based theme's is that ThemeData.accentColor is set to color scheme primary and not to secondary. This is done to get an easy way for borders on TextField.decoration to use theme based primary color in dark-mode, and not accentColor color. There may be a bug in the way InputDecorationTheme gets used by the InputDecorator. We were unable to define a theme that would work correctly for such a setup without resorting to making accentColor equal to ThemeData.primaryColor. This definition has less of an impact visually to any built-in widgets than one might suspect. With our other existing theme definitions we saw no other widget that used accentColor. FAB and toggles have their own theme and colors, so they still use the default expected colorScheme.secondary color, despite this change.

• In TextSelectionThemeData, the standard for selectionColor is colorScheme.primary with opacity value 0.4 for dark and 0.12 light mode. Here primary with 0.5 for dark-mode and 0.3 for light mode is used. The standard for selectionHandleColor is colorScheme.primary, here we use the slightly darker shade primaryColorDark instead, which does not have a proper definition in Flutter standard ColorScheme based themes.

• A predefined slightly opinionated InputDecorationTheme is used. It sets filled to true and fill color to color scheme primary color with opacity 0.035 in light mode and opacity 0.06 in dark-mode. The other key theme change is done via modification of the ThemeData.accentColor described earlier. Since the theme does not define a border property of TextField in an app can still easily use both the default underline style, or the outline style by specifying the default const OutlineInputBorder() for the border property. If you don't want the filled style, or the primary colored borders in dark-mode, you can override them back with copyWith.

• The property fixTextFieldOutlineLabel is set to true by default, it looks much better.

• Button theming is applied to ThemeData.buttonColor using color scheme primary. The entire color scheme is passed to old button's ButtonThemeData and it uses textTheme set to ButtonTextTheme.primary, with minor changes to padding and tap target size, it makes the old buttons almost match the default design and look of their corresponding newer buttons. Thus RaisedButton looks very similar to ElevatedButton, OutlineButton to OutlinedButton and FlatButton to TextButton. There are some differences in margins and looks, especially in dark-mode, but they are close enough. This is a button style we used before the introduction of the new buttons with their improved defaults. It just happened to be very close as theme was based on how things looked in the design guide prior to Flutter releasing the new buttons that fully implement the correct design.

  The newer buttons are thus still nicer, especially when it comes to their interactions and all the theming options they provide, but they are tedious to theme. If you want to make custom styled buttons we still recommend using the newer buttons instead of the old ones, as they offer more customization possibilities. Still, this theming applied to the old buttons make them look close enough to the new ones, with their nice defaults. To the extent that most might not even notice if you still use the old buttons.

• The default theme for Chips contain a design bug that makes the selected ChoiceChip() widget look disabled in dark-mode, regardless if created with ThemeData or ThemeData.from factory. See issue: https://github.com/flutter/flutter/issues/65663 The used ChipThemeData modification fixes the issue.

• The FloatingActionButtonThemeData is set as follows:

  FloatingActionButtonThemeData(
       backgroundColor: colorScheme.secondary,
       foregroundColor: colorScheme.onSecondary),
  

  In order to ensure the same FAB style that was the default in ThemeData factory via accentIconTheme in the past. If it is not defined we get a deprecated warning like this:

  Warning: The support for configuring the foreground color of FloatingActionButtons using ThemeData.accentIconTheme has been deprecated. Please use ThemeData.floatingActionButtonTheme instead. See https://flutter.dev/go/remove-fab-accent-theme-dependency. This feature was deprecated after v1.13.2.

• For TabBarTheme a default design that fits with surface color is used, instead of one that fits with the app bar color.

• The BottomNavigationBarThemeData uses color scheme primary color for the selected item. Flutter defaults to secondary color. Primary color is the design commonly used on iOS for the bottom navigation bar. We agree and think it looks better as the default choice in apps.

• Default tooltip theming in Flutter is currently a bit flawed on desktop and web using very small 10dp font. See issue: https://github.com/flutter/flutter/issues/71429

  The default theming also does not handle multiline tooltips very well. The used TooltipThemeData theme design corrects both issues. It uses 12dp font on desktop and web instead of 10dp, and some padding over height constraint to ensure multiline tooltips look nice too. FlexColorScheme also includes a new property tooltipsMatchBackground that can be toggled to not used Flutter's Material default theme mode inverted background. Tooltips using light background in light theme and dark in dark, are commonly used on Windows desktop platform. You can tie the extra property to used platform to make an automatic platform adaptation of the tooltip style, or give users a preference toggle if you like.

• On Android devices a setSystemUIOverlayStyle call makes the AppBar one-colored like on iOS, which looks better (opinionated). It would be nice if we could also make the system navigation button area on Android transparent, but it does not work if we set systemNavigationBarColor to a transparent color. It is doable, but requires modifying Android config files, not possible as far as I have seen from Flutter only. Related issue: https://github.com/flutter/flutter/issues/69999.