javafx-fluent-theme

This is a custom theme for JavaFX to make your application look like a Windows 11 (WinUI) program. It replaces modena.css with styles that follow Microsoft's Fluent design language. In addition, you can apply Windows 11's Mica effect to your window, or override Windows' default window title bar for complete client-side decorations.

Take a look at the example application, or see here how to achieve Windows' built-in effects.

See here for the list of styled controls, and to see which is still missing.

---

The theme and example application are written in Kotlin and built with Gradle. FluentLib.dll is required to call Windows' internal functions. It is created by a Visual Studio project located in FluentLib/.

theme/      # CSS theme and custom JavaFX controls which can be used as a library
FluentLib/  # Windows DLL to get access to Mica/title bar replacement
demo/       # demo application that uses the theme and DLL

The theme (currently, only a light theme is available) is built by SASS with files in theme/src/main/css.

Setup/Installation

The whole theme package includes CSS styling, custom skins, and a FluentApp abstract class that takes care of setting everything up. If you want to use the whole package, you need to build it locally, and then include it in your dependencies.

Alternatively, you can just copy the CSS file into your project if you just want to change the look of the controls. However, some controls use custom skins to e.g. enable animations. See the list of controls here.

If you want to use Windows' internal functions that are made available in FluentApp, you need to load FluentLib.dll in your code. FluentApp takes care of that, but the DLL must be available for the application, which is usually where the process is being executed; in a Gradle environment, put it where gradlew.bat is located.

You can download a pre-built DLL from the Releases.

Usage

As a first step, run FluentApp.initialize() as soon as possible, before calling any JavaFX code. For example, in this Main.kt file:

fun main() {
    FluentApp.initialize()
    launch(YourApp::class.java)
}

This takes care of loading the FluentLib DLL, and does some checks so that the Mica effect works (see Issues).

For the YourApp class, subclass FluentApp which sets up the custom theme and any other effects (see below) for you. It only has a single abstract method (onCreateStage(Stage)). In general, whatever you do in start(), you should now do in onCreateStage, with some exceptions:

• Don't change the Stage style using initStyle.
• Don't call primaryStage.show(). FluentApp takes care of that.

Manual setup

If you want to set up the theme manually without subclassing FluentApp, make sure to:

• Override modena.css as early as possible with setUserAgentStylesheet("fluent-light.css")
• If you want to use Mica/other effects, load the DLL as early as possible: System.loadLibrary("FluentLib")
• If you want to use Mica/other effects, set your stage's style to StageStyle.UNIFIED
• Only use methods from the FluentLib DLL after primaryStage.show()

Enabling Windows 11's Mica effect

Windows 11's "Mica" effect can be activated with this library's Windows.setMicaFor(String, Boolean) method (coming from FluentLib.dll). However, you need to make sure that:

• Your stage's style is StageStyle.UNIFIED
• There is no background set wherever Mica should "shine through", e.g. any node should have -fx-background-color: transparent, and the Scene should be instantiated with Scene(root, Color.TRANSPARENT)
• Call Windows.setMicaFor(String, Boolean) providing your window title after the stage is show()n.
• You can enable or disable the effect using the same method.

Issues

While it's generally possible to get the Mica effect without using Microsoft's blessed ways, it seems it is a little unreliable under JavaFX when using certain types of GPUs. More info is available here: Graphic issues on certain GPUs

When you see a "glitched" Mica effect, try using software rendering first by setting this as early as possible (i.e. before calling JavaFX' launch):

System.setProperty("prism.order", "sw")

If Mica works with this, there is a good chance that you only need to enable a hidden flag on non-AMD GPUs. Remove the prism.order flag, and run this code as early as possible:

System.setProperty("prism.forceUploadingPainter", "true")
System.setProperty("javafx.animation.fullspeed", "true") // When on monitors >60Hz

FluentApp.initialize() takes care of that automatically, but my current check for AMD GPUs isn't very sophisticated. Feel free to raise any issues if e.g. the demo application looks "weird" on your setup (usually, a black background).

Removing Windows' default title bar

Windows' default title bar normally shows a small icon and the window title. You can remove this title bar and merge the content area with the window controls to use this "unused" space. Many macOS and GTK applications use a similar design which arguably looks a little more modern.

The Win32 equivalent is called DwmExtendFrameIntoTitleBar. There is actually code in JavaFX that uses this, but it doesn't seem to work reliably. With javafx-fluent-theme, you get another direct way to achieve this Window styling. Follow this:

• The Stage's window style must be StageStyle.UNIFIED.
• After primaryStage.show(), call Windows.setHeaderBarFor(String, Boolean) providing your window's title to remove the title bar.
• The effect can be toggled back and forth using the same method.

Depending on your scene background, the window controls at the top right might disappear. This is because the background is painted over these controls (although Windows will still react to click events there). To see the window controls, make sure not to set any background (e.g. with CSS) or only use transparent where the window controls might be painted over.

Combined with the Mica effect from above (which requires a transparent background), the window controls will appear again, giving you a nice, Windows 11-styled application:

Here, the first node of my JavaFX scene is a custom HeaderBar node (sub-classing HBox) which just shows a button (the back arrow).

Without a title bar, you will lose the option to drag the window around with a mouse. Because of that, this library also provides a DragPane which you should put somewhere in your HeaderBar node. The nice thing about this is that it will capture Windows' native events, and e.g. trigger Windows' snap layouts when moving the window around.

An example header bar:

<HeaderBar>
    <padding>
        <Insets top="4.0" right="8.0" bottom="4.0" left="8.0"/>
    </padding>
    <Button text="&#xe830;" styleClass="borderless-button, back-button" disable="true"></Button>
    <DragPane HBox.hgrow="ALWAYS"/>
</HeaderBar>

As with the Mica example above, you can subclass FluentApp instead and pass useHeaderBar: to its constructor to have this done at startup.

---

Demo application

The demo application is roughly designed after "WinUI 3 Gallery". So far I mostly added the controls as opposed to containers like StackPanel/StackPane. Take a look at the list of controls below to see what is missing.

I renamed "System Backdrops (Mica/Acrylic)" (found under "Styles") to "Window background", and "TitleBar" (under "Windowing") to "HeaderBar".

Additionally, Spinner is put under "Basic input" instead of "Text" (where WinUI puts "NumberBox").

Note:

• The back button is only showcasing what you can put in place of a title bar, and not working yet.
• There is no application icon yet.

Building

The demo application requires FluentLib.dll in its working directory, so either build it from FluentLib/, or download a pre-built x64 DLL from the Releases, and put it under demo/.

---

Appendix

Design guidelines

javafx-fluent-theme will set grayscale antialiasing which is the default for Window applications using UWP (in the past) or WinUI.

I mostly tried to follow the designs found in Microsoft's gallery application. When I first started my designs, most of them came from "WinUI 2 Gallery" and only later "WinUI 3 Gallery" caught up with Microsoft's latest designs, so there might still be some subtle differences between Microsoft's most current styles.

In my own designs, I try not to use any title case when labelling buttons or other controls, but only capitalize the first letter.

Non-goals

• Support on macOS or using JavaFX with GTK
• Compatibility with Windows 10 (Windows 11 replaces the previous Segoe MDL2 Assets with Segoe Fluent Icons which is used throughout this project, and which is not guaranteed to be available on Windows 10).

Table of JavaFX/WinUI controls

(Status: Done = styled & done; WIP = Added but not everything styled yet; Missing = Not added yet; Skipped = not planning on working on it)

JavaFX	WinUI	Status	CSS only?†
Button	Button	Done	YES
CheckBox	CheckBox	Done	YES
ChoiceBox	ComboBox	Done	YES
ColorPicker	ColorPicker	Missing	-
ComboBox	ComboBox	Done	YES
ContextMenu	(several)	Done	NO‡
DatePicker	CalendarDatePicker, DatePicker	Done	YES
HTMLEditor	-	Skipped	-
Hyperlink	HyperlinkButton	Done	YES
ImageView	Image	Done	YES
Label	TextBlock	Done	YES
ListView	ListView	Missing	-
MediaView	MediaPlayerElement	Skipped	-
MenuBar	MenuBar	WIP	YES
MenuButon	DropDownButton	Done	YES
Pagination	-	Skipped	-
PasswordField	PasswordBox	Done	YES
ProgressBar	ProgressBar	Done	YES
ProgressIndicator	ProgressRing	Skipped	-
RadioButton	RadioButton	Done	YES
ScrollBar	ScrollBar	Done	YES
Separator	(AppBarSeparator)	Done	YES
Slider	Slider	Done	NO
Spinner	NumberBox	Done	NO
SplitMenuButton	SplitButton	Missing	-
TableView	DataGrid	Missing	-
TextArea	TextBox	Done	YES
TextField	TextBox	Done	YES
ToggleButton	ToggleButton	Done	YES
Tooltip	ToolTip	Done	NO‡
TreeTableView	DataGrid (I think)	Skipped	-
TreeView	TreeView	WIP	-
WebView	WebView2	Skipped	-

^†This means that no custom Skin is used to add any custom behavior. You could simply copy-paste the CSS attributes to get the design.

^‡The control can be styled only with CSS, but you instantiate Fluent[Name] if you want to have "fluent animations".

Additionally, the following containers/panes are available or currently in preparation:

JavaFX	WinUI	Status	CSS only?
Dialog	ContentDialog	Missing	-
SplitPane	SplitView	Missing	-
TabPane	TabView	Missing	-
TitledPane	Expander	Done	YES
ToolBar	CommandBar	Missing	-

Gallery

Here are my JavaFX applications that I styled with this theme:

---

This project is published under the zlib license (see LICENSE file in this repository).

Copyright (C) 2023-2024 Eroica

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not
   claim that you wrote the original software. If you use this software
   in a product, an acknowledgment in the product documentation would be
   appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.