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Architecture

In This Article

Actipro Themes contains a complete framework for managing run-time selection of the themes of both Actipro and native controls but can also be used for your own custom controls as well.

Themes are dynamically generated based on theme definitions, which allow for you to configure various appearance options prior to theme generation. This topic covers the underlying architecture for the themes and describes how theme definitions are used to configure generated themes.

Actipro's Theme Designer application comes with the WPF Controls, making it easy to fully configure a theme definition and see how various options affect appearance. The Theme Designer even generates the code necessary to paste into your application OnStartup to replicate the theme definition.

What are Themes?

Themes are resource dictionaries that define styles and templates for a group of controls. Each theme has its own visual appearance that it creates. For instance, a Ribbon can be rendered in an Office blue theme or a modern dark theme, among many others.

Some resource dictionaries may be used to provide the styles and templates for controls, while others may simply define asset resources, such as brushes and pens. Still others may tie those combinations together to provide a complete theme implementation.

The Actipro ThemeManager allows you to specify a particular theme to use for all Actipro controls, and optionally native WPF controls as well.

Theme Generation

Prior to v2020.1, each predefined Actipro theme consisted of large resource dictionaries with fixed asset resources (brushes, etc.). While this worked well, it was difficult to know which asset resources to customize if you wished to override some of the defaults for a theme. For v2020.1, we updated our theming system to dynamically generate the resource dictionaries at run-time based on a configurable theme definition. This allows you to adjust the generated theme to suit your needs, such as if you wish to change the hue of accent colors used or general border contrast.

Note that the optional Aero-style themes still use the older design of loading a large resource dictionary with predefined asset resources. This is done so that they retain their very customized appearance. All other more modern themes are based on the newer theme definition design.

Theme Definition Overview

Theme definitions are represented by the ThemeDefinition class. They have many options that are interpreted by the Actipro theme generator when dynamically building a resource dictionary containing assets for a theme.

Theme definitions allow for easy configuration of these kinds of options:

  • Intent of a white, light, dark, or black theme.
  • Base colors used to define the color palette for color families.
  • Hue and saturation to tint grayscale colors.
  • Color families used for various UI such as accents and windows.
  • Font family and font sizes.
  • Arrow and glyph kinds.
  • Border contrast amounts.
  • Corner radii, padding, and margins.
  • Title and status bar backgrounds.

Registering and Using a Theme Definition

This sample code shows how to create a basic ThemeDefinition whose name is "Custom", register it with the ThemeManager, and then tell the theme manager to use it as the current theme. Note that we also tell the theme manager to theme native WPF controls. The generated theme will be dark colors with green accents.

public partial class App : Application {

	protected override void OnStartup(StartupEventArgs e) {
		// Configure the Actipro theme manager
		ThemeManager.BeginUpdate();
		try {
			// Register the theme definitions for your application
			ThemeManager.RegisterThemeDefinition(new ThemeDefinition("Custom") {
				Intent = ThemeIntent.Dark,
				PrimaryAccentColorFamilyName = ColorFamilyName.Green,
				WindowColorFamilyName = ColorFamilyName.Green,
			});

			// Use the Actipro styles for native WPF controls that look great with Actipro's control products
			ThemeManager.AreNativeThemesEnabled = true;

			// Set the current app theme via a registered theme definition name
			ThemeManager.CurrentTheme = "Custom";
		}
		finally {
			ThemeManager.EndUpdate();

		// ...

		// Call the base method
		base.OnStartup(e);
	}

}

Call the ThemeManager.RegisterThemeDefinition method for each theme definition to register. Multiple theme definitions can be registered with the theme manager, but make sure each theme definition has a unique name. The ThemeManager.CurrentTheme property is later set to the name of the theme to load for the application. The names of predefined themes are available as constants in the ThemeNames class.

Automatic Light and Dark Theme Switching

Windows has a system setting where the user can indicate if they prefer light or dark themed applications. Say that you've created and registered two theme definitions (light and dark) for your application and you wish for those themes to follow the Windows system setting. This is easily done with the Actipro theme manager.

This sample code shows how two theme definitions could be registered (replace the ellipses with appropriate theme definition property settings) and the theme manager told to select a theme based on the Windows system preference setting for light or dark apps. Note that no call to the ThemeManager.CurrentTheme property is needed in this scenario. The ThemeManager.RegisterAutomaticThemes call will switch the theme if necessary.

ThemeManager.RegisterThemeDefinition(new ThemeDefinition("MyLightTheme") { ... });
ThemeManager.RegisterThemeDefinition(new ThemeDefinition("MyDarkTheme") { ... });
ThemeManager.RegisterAutomaticThemes("MyLightTheme", "MyDarkTheme", ThemeNames.HighContrast);

Behind the scenes, ThemeManager attaches a Win32 message hook on the Application.MainWindow to listen for messages from the system that indicate theme changes. When one is detected the ThemeManager.SystemApplicationMode property is updated and if automatic theme switching is enabled, the theme is changed.

Important

If you use a splash screen for your application, the ThemeManager may initially attach its hook to that splash screen Window since it would be the value in Application.MainWindow. WPF's Application class doesn't notify when Application.MainWindow changes. If you later set a new main Window to Application.MainWindow, the hook can be updated to that Window by a call to the ThemeManager.RegisterAutomaticThemes method, which ensures the hook is attached to the current Application.MainWindow.

High-Contrast Support

The Actipro theme generator has complete support for high-contrast themes. When the ThemeDefinition.Intent property is set to HighContrast, only system colors will be used for generated brush resource assets. This allows your application to be rendered properly for end users who require high-contrast.

Note

A HighContrast theme intent should only ever be used when Windows itself is in high-contrast mode.

The ThemeManager.RegisterAutomaticThemes method described in the previous section has a third parameter that allows for a high-contrast theme name to be specified, which generally is ThemeNames.HighContrast. When a theme name is passed in, the theme manager will watch for the system to change into high-contrast mode and will automatically activate/deactivate that theme as appropriate.

Theme Definition Base Classes

There are several theme definition classes that provide their own set of default values. It's best to use the base class that is closest to the look you wish to achieve with your theme, so fewer options need to be set.

Theme Definition Important Options

The most important options of a theme definition are its Name and Intent.

The Name property must be a string that uniquely identifies the theme definition. Once the theme definition is registered with the theme manager, it can be used to generate a theme when its name is set to the ThemeManager.CurrentTheme property.

The Intent property specifies a ThemeIntent enumeration value that indicates if the theme definition is intended to be a black, dark, light, or white theme. This setting heavily affects the grayscale and color shades that are used in the theme.

Theme Definition Color Palette Options

Each theme definition generates multiple shades of colors in various color families. The ColorPaletteKind property specifies a ColorPaletteKind enumeration value that indicates the default color palette to use for the generated color families.

  • Vibrant - Bright colors.
  • Office - Colors are similar to slightly more muted Office colors.

The properties for the base colors used to generate each color family can be altered from their color palette defaults. This is useful when you wish to tweak the color family shades to match your brand colors.

The base colors for each color family are listed below:

Theme Definition Grayscale Palette Options

All grayscale (silver and gray shades) are tinted towards a particular color hue. The BaseGrayscaleHue property determines this hue value in degrees from 0 to 359.

The BaseGrayscaleSaturation property determines the level at which the color hue is saturated into the grayscale shades. A higher number means a higher saturation level.

The GrayMin and SilverMax properties indicate the minimum and maximum component values to use for the generated grayscale shades. Raise the gray minimum to not have as dark of a theme. The silver maximum generally remains 255 to ensure white can be used.

The GraySilverRatio is a ratio percentage indicating how the gray shades and silver shades share the entire grayscale spectrum. The default value is 0.5, meaning they share the spectrum equally.

Theme Definition Color Family Usage Options

Several options let you select the color family to use for various UI areas. For instance, if you want the primary accent color for hover states, etc. in your application to be green, you'd alter the PrimaryAccentColorFamilyName property.

Theme Definition Font Options

The DefaultFontFamily property specifies the default font family to apply to all top-level elements like Window, ContextMenu, and ToolTip controls. When left its default value of null, the system-defined result of the SystemFonts.MessageFontFamily property is used. On English systems, this default value is generally "Segoe UI". It is recommended to not specify the default font family unless you have a specific stylistic need for another font family.

The BaseFontSize property indicates the base font size to use for most UI. Window titles (when using WindowChrome) will use the relative font size specified in the WindowTitleFontSizeKind property. Likewise, tool window titles will use the relative font specified in the ToolWindowContainerTitleFontSizeKind property.

Theme Definition Other Options

There are many other appearance options that can be configured as well.

Arrow Kinds

The ArrowKind property specifies an ArrowKind enumeration value that indicates whether chevron or filled triangle arrows should be used throughout the UI.

Borders

The RequireDarkerBorders property specifies whether dark-oriented themes should use darker-than-background borders instead of lighter-than-background borders. When this property is true in a dark theme, it's best to use a higher GrayMin, which will allow the darker borders to be more distinctive. The GraySilverRatio can optionally be slightly increased to reduce overall border contrast.

Bullets

Several options like BulletBorderWidth, BulletGlyphKind, BulletRelativeSize, and CheckBoxCornerRadius determine how CheckBox and RadioButton bullets render.

Buttons and Bar Items

Several options like BarItemBackgroundGradientKind, BarItemBackgroundStateKind, BarItemBorderContrastKind, ButtonBackgroundGradientKind, ButtonBorderContrastKind, ButtonCornerRadius, ButtonPadding, and ToolBarButtonCornerRadius determine how buttons render.

Containers

The ContainerBorderContrastKind property alters how container borders render.

List Items

Several options like ListItemBackgroundGradientKind, ListItemBackgroundStateKind, and ListItemBorderContrastKind determine how list items render.

Several options like MenuItemLargeIconColumnWidth, MenuItemIconColumnWidth, MenuItemPopupColumnWidth, MenuItemPadding, and MenuPopupCornerRadius determine how menus render.

Popups

Several options like PopupBorderContrastKind, PopupCornerRadius, and PopupShadowDirection determine how popups render.

Scroll Bars

Several options like ScrollBarHasButtons, ScrollBarThumbCornerRadius, and ScrollBarThumbMargin determine how scroll bars render.

Status Bars

The StatusBarBackgroundKind property alters how status bars render.

Tabs

The TabCornerRadius property alters how tabs render.

Windows and Title Bars

Several options like WindowTitleBarBackgroundKind, TitleBarCornerRadius, and WindowBorderKind determine how windows and title bars render.

Traditional WPF Themes (System-Based Switching)

Important

With Windows 10-based and newer systems being the primary operating system used at this point, much of the system-based theming described below is now obsolete. Modern Actipro controls all implement a single Generic.xaml file for their styles/templates and theming is based on the Actipro theme definition used.

There are many resources on the web describing how the non-Actipro WPF's themes system traditionally works but here is a brief overview. You can optionally define a number of XAML resource dictionary files in a Themes folder off of your project root. Special filenames include:

  • Generic.xaml - The default resources that are always loaded but can be overridden by other ones below
  • Classic.xaml - "Classic" Windows 9x/2000 look
  • Luna.NormalColor.xaml - Windows XP default blue theme
  • Luna.Homestead.xaml - Windows XP olive green theme
  • Luna.Metallic.xaml - Windows XP silver theme
  • Royale.NormalColor.xaml - Windows XP Media Center Edition theme
  • Aero.NormalColor.xaml - Windows Vista/7 default theme
  • Aero2.NormalColor.xaml - Windows 8.x/10 default theme
  • AeroLite.NormalColor.xaml - Windows Server 2012 default theme

Basically, if the user is running Windows XP with the olive green theme active, the Luna.Homestead.xaml file, if found, will be loaded so that anything in the application can use its resources (styles, brushes, etc.). These resources are loaded like this on demand, when WPF encounters the first control or ComponentResourceKey lookup corresponding to the given assembly. Also note that the System.Windows.ThemeInfoAttribute must be assigned to your assembly context indicating that themed-resources are in the assembly. See the MSDN for documentation on this attribute.

Theme Catalogs

Theme catalogs can be used to indicate which resource dictionaries should be loaded for any given theme. The theme catalogs contain zero or more resource dictionary references, which map a resource dictionary to one or more themes by name. When the current theme is changed, the theme manager will then query each registered theme catalog to find the resource dictionaries that must be loaded for the given theme.

Each of these resource dictionaries can contain many assets, such as brushes, specific to a theme. For instance, you may wish to override some brushes used in one of the predefined themes. To do this, you would make a resource dictionary with the brush overrides, then register that resource dictionary with a theme catalog to load for the target theme name.

Resource dictionary references are represented by instances of ThemedResourceDictionaryReference, which include a Uri to the XAML file for the ResourceDictionary and a list of associated theme names. Therefore, a single reference can indicate a single XAML file should be loaded for multiple themes.

Registration

Theme catalogs can be manually registered using the ThemeManager.RegisterThemeCatalog method. They can also be unregistered using the ThemeManager.UnregisterThemeCatalog method. A key can be used to uniquely identify a theme catalog during registration, so it can be more easily removed later.

Custom registrars, which derive from ThemeCatalogRegistrarBase, can be used to automatically register a system theme catalog with the theme manager when WPF loads the system themes for an assembly.

To accomplish this, a custom ThemeCatalogRegistrarBase is created that passes the desired theme catalog type as the type parameter. This registrar can then be included in the XAML files loaded by WPF and it will automatically register the theme catalog when loaded.

Tip

It is a best practice to register custom theme catalogs upfront in the application startup code. The tradeoff is that registering a theme catalog at app startup will force that assembly to load immediately and will incur the time cost of loading the assembly, but will prevent templates from being reapplied later during app usage when a themed control from a control library is first used.