# Substance look and feel - skins overview

A skin is a set of information to paint top-level Swing windows, such as frames and dialogs. The `org.jvnet.substance.api.SubstanceSkin` contains all the APIs officially supported by Substance skins.

The skin definition consists of the following:

- Decoration areas and color scheme bundles:

- List of supported decoration areas.
- Color scheme bundles for the supported decoration areas.
- Optional background color schemes for the supported decoration areas.

- Watermarking:

- Optional watermark.
- Optional watermark color scheme.

- Painters:

- Gradient painter.
- Decoration painter.
- Highlight painter.
- Border painter.

- Miscellaneous:

- Button shaper.
- Optional list of decoration area types that have drop shadow borders on the top pixels.
- Optional values for start and end values of selected tab fade.

### Skin definition

In order to define a valid skin, you need to specify all its mandatory parameters. A valid skin must have a color scheme bundle for `DecorationAreaType.NONE`, button shaper, gradient painter, decoration painter, highlight painter and border painter. All other parameters are optional.

The documentation on decoration painters explains the notion of a decoration area type. While a valid skin must define a color scheme bundle for `DecorationAreaType.NONE`, all other decoration area types are optional. Different skins have different sets of decoration areas that are painted. For example, the core Moderate skin decorates only `DecorationAreaType.PRIMARY_TITLE_PANE` and `DecorationAreaType.SECONDARY_TITLE_PANE`, while the core BusinessBlueSteel decorates additional `DecorationAreaType.HEADER`, `DecorationAreaType.TOOLBAR`, `DecorationAreaType.FOOTER` and `DecorationAreaType.GENERAL`:

In order to register a custom color scheme bundle and an optional background color scheme on the specific decoration area type(s), use the following APIs:

`/**
* Registers the specified color scheme bundle to be used on controls in
* decoration areas.
*
* @param bundle
* The color scheme bundle to use on controls in decoration areas.
* @param areaTypes
* Enumerates the area types that are affected by the parameters.
*/
public void registerDecorationAreaSchemeBundle(
SubstanceColorSchemeBundle bundle, DecorationAreaType... areaTypes)
/**
* Registers the specified color scheme bundle and background color scheme
* to be used on controls in decoration areas.
*
* @param bundle
* The color scheme bundle to use on controls in decoration areas.
* @param backgroundColorScheme
* The color scheme to use for background of controls in decoration
* areas.
* @param areaTypes
* Enumerates the area types that are affected by the parameters.
*/
public void registerDecorationAreaSchemeBundle(
SubstanceColorSchemeBundle bundle,
SubstanceColorScheme backgroundColorScheme,
DecorationAreaType... areaTypes)`

Decoration areas registered with these APIs will have their background painted by the skin's decoration painter based on the default color scheme of the registered color scheme bundle. You can also use the following API to use a custom default color scheme on the specified decoration area types (in this case the controls in those decoration areas will use the default color scheme bundle):

`/**
* Registers the specified background color scheme to be used on controls in
* decoration areas.
*
* @param backgroundColorScheme
* The color scheme to use for background of controls in decoration
* areas.
* @param areaTypes
* Enumerates the area types that are affected by the parameters. Each
* decoration area type will be painted by {@link
* SubstanceDecorationPainter#paintDecorationArea(Graphics2D,
* Component, DecorationAreaType, int, int, SubstanceSkin)}.
*/
public void registerAsDecorationArea(
SubstanceColorScheme backgroundColorScheme,
DecorationAreaType... areaTypes)`

Here is an example of specifying the default color scheme bundle for the core Business Blue Steel skin:

`SubstanceColorScheme activeScheme = new SteelBlueColorScheme()
.tint(0.15);
SubstanceColorScheme defaultScheme = new MetallicColorScheme()
.tint(0.05);
SubstanceColorScheme disabledScheme = new LightGrayColorScheme()
.tint(0.05);
SubstanceColorSchemeBundle defaultSchemeBundle = new SubstanceColorSchemeBundle(
activeScheme, defaultScheme, disabledScheme);
defaultSchemeBundle
.registerHighlightColorScheme(new BlendBiColorScheme(
new TerracottaColorScheme(), new SunGlareColorScheme(),
0.5).tint(0.2));
this.registerDecorationAreaSchemeBundle(defaultSchemeBundle,
DecorationAreaType.NONE);`

and a custom color scheme bundle for the header-type decoration areas:

`SubstanceColorSchemeBundle headerSchemeBundle = new SubstanceColorSchemeBundle(
activeScheme.saturate(0.2), activeScheme.saturate(-0.2),
disabledScheme);
this.registerDecorationAreaSchemeBundle(headerSchemeBundle,
DecorationAreaType.PRIMARY_TITLE_PANE,
DecorationAreaType.SECONDARY_TITLE_PANE,
DecorationAreaType.HEADER, DecorationAreaType.TOOLBAR);`

And here is an example of specifying a number of decoration area types to have their background painted by the decoration painter and the specific color scheme, without registering a custom color scheme bundle for those areas:

`this.registerAsDecorationArea(defaultScheme,
DecorationAreaType.PRIMARY_TITLE_PANE,
DecorationAreaType.SECONDARY_TITLE_PANE,
DecorationAreaType.HEADER, DecorationAreaType.FOOTER,
DecorationAreaType.GENERAL);`

You can use the following API to have drop shadows painted on the top pixels of the specific decoration areas:

`/**
* Marks the specified area type to have drop shadows on the top few pixels.
*
* @param decorationAreaType
* Decoration areas of this type will have drop shadows on the top few
* pixels.
*/
public void setPaintingDropShadows(DecorationAreaType decorationAreaType)`

Here is how the core Nebula skin is configured to paint drop shadows on the toolbars:

`this.setPaintingDropShadows(DecorationAreaType.TOOLBAR);`

and here is how it looks like:

If you are extending a core skin and wish to remove drop shadow painting, use the following API:

`/**
* Marks the specified area type to not have drop shadows on the top few
* pixels.
*
* @param decorationAreaType
* Decoration areas of this type will not have drop shadows on
* the top few pixels.
*/
public void unsetPaintingDropShadows(DecorationAreaType decorationAreaType)`

You can use the following APIs to configure the start and end values for the selected tab fade:

`/**
* Sets the start of fade effect on the selected tabs in {@link JTabbedPane}
* s. The value should be in 0.0-1.0 range.
*
* @param selectedTabFadeStart
* The start of fade effect on the selected tabs in {@link JTabbedPane}
* s. Should be in 0.0-1.0 range.
*/
public void setSelectedTabFadeStart(double selectedTabFadeStart)
/**
* Sets the end of fade effect on the selected tabs in {@link JTabbedPane}s.
* The value should be in 0.0-1.0 range.
*
* @param selectedTabFadeEnd
* The end of fade effect on the selected tabs in {@link JTabbedPane}s.
* Should be in 0.0-1.0 range.
*/
public void setSelectedTabFadeEnd(double selectedTabFadeEnd)`

By default, the fade start is at 0.1 and the fade end is at 0.3 - here is how it looks like on the core Sahara skin:

Here is how these APIs are used in the core Creme skin to specify a slightly larger selected tab fade:

`this.setSelectedTabFadeStart(0.2);
this.setSelectedTabFadeEnd(0.4);`

and this is how it looks like:

All the other settings (watermark, painters, watermark color scheme) are set in the skin constructor. Here is sample code from the core Office Silver 2007 skin:

`this.buttonShaper = new ClassicButtonShaper();
this.watermark = new SubstanceStripeWatermark();
this.gradientPainter = new ClassicGradientPainter();
this.borderPainter = new ClassicInnerBorderPainter(0.8f,
ColorShiftKind.TINT);
BrushedMetalDecorationPainter decorationPainter =
new BrushedMetalDecorationPainter();
decorationPainter.setPaintingSeparators(true);
decorationPainter.setTextureAlpha(0.45f);
this.decorationPainter = decorationPainter;
this.highlightPainter = new ClassicHighlightPainter();`

### Management APIs

`public static Map<String, SkinInfo> getAllSkins()`
Returns all available skins.

`public static boolean setSkin(String skinClassName)`
Sets the specified skin.

`public static boolean setSkin(SubstanceSkin skin)`
Sets the specified skin.

`public static SubstanceSkin getCurrentSkin(Component c)`
Returns the current skin for the specified component.

`public static void registerSkinChangeListener(
SkinChangeListener skinChangeListener)`
Registers a new listener on skin change.

`public static void unregisterSkinChangeListener(
SkinChangeListener skinChangeListener)`
Unregisters a listener on skin change.

`SubstanceLookAndFeel.SKIN_PROPERTY`
Property name for specifying skin to be used on the specific root pane.

As with color scheme bundles, it is possible to create a derived skin. The same warning applies - a skin is a delicate collection of different color scheme bundles, painters and additional settings carefully chosen to work together in providing visually appealing appearance and consistent animation sequences. In some cases, creating a derived skin will result in poor visuals.

You can use the following API to create a derived skin:

`/**
* Creates a new skin that has the same settings as this skin with the
* addition of applying the specified color scheme transformation on all the
* relevant color schemes
*
* @param transform
* Color scheme transformation.
* @param name
* The name of the new skin.
* @return The new skin.
*/
@SubstanceApi
public SubstanceSkin transform(ColorSchemeTransform transform,
final String name)`

Where the color scheme transformation is defined by the following interface:

`/**
* Defines transformation on a color scheme.
*
* @author Kirill Grouchnikov
*/
@SubstanceApi
public interface ColorSchemeTransform {
/**
* Transforms the specified color scheme.
*
* @param scheme
* The original color scheme to transform.
* @return The transformed color scheme.
*/
public SubstanceColorScheme transform(SubstanceColorScheme scheme);
}`

### Available skins

- Toned down skins
- Dark skins
- Saturated skins

### Providing custom skins

Substance provides an option for specifying custom skin. This option uses the Substance plugin mechanism to discover additional skins at runtime. As with all Substance plugins, you must pack an additional XML configuration file in one of your runtime jarfiles. The name of this file must be `META-INF/substance-plugin.xml` and it must comply with the following syntax:

`

    <laf-plugin>
       additional optional tags
       <skin-plugin-class>...</skin-plugin-class>
       additional optional tags
    </laf-plugin>

`

The contents of `skin-plugin-class` tag must be the fully-qualified class name of a class that implements the `SubstanceSkinPlugin` interface. This interface specifies the following methods:

`/**
* Returns information on all available skins in <code>this</code> plugin.
*
* @return Information on all available skins in <code>this</code> plugin.
*/
public Set<SkinInfo> getSkins();
/**
* Returns the class name of the default skin.
*
* @return The class name of the default skin.
*/
public String getDefaultSkinClassName();`

The `SkinInfo` class contains information on single (base or custom) skin.

Note that using this option you may override the skins supplied with Substance base package (by specifying the same display name). This behaviour, however, is not guaranteed to be consistent across various VMs and class loaders, since the skin plugins are processed in random order.