Module javafx.graphics
Package javafx.css

Class CssMetaData<S extends Styleable,V>

  • Type Parameters:
    S - The type of Styleable
    V - The type into which the parsed value is converted.
    Direct Known Subclasses:
    FontCssMetaData
    public abstract class CssMetaData<S extends Styleable,V>
extends Object
    A CssMetaData instance provides information about the CSS style and provides the hooks that allow CSS to set a property value. It encapsulates the CSS property name, the type into which the CSS value is converted, and the default value of the property.

    CssMetaData is the bridge between a value that can be represented syntactically in a .css file, and a StyleableProperty. There is a one-to-one correspondence between a CssMetaData and a StyleableProperty. Typically, the CssMetaData of a Node will include the CssMetaData of its ancestors. For example, the CssMetaData of a Rectangle includes the CssMetaData of Shape and also of Node. During CSS processing, the CSS engine iterates over the Node's CssMetaData, looks up the parsed value of each property, converts the parsed value, and sets the value on the StyleableProperty.

    The method Node.getCssMetaData() is called to obtain the List<CssMetaData>. This method is called frequently and it is prudent to return a static list rather than creating the list on each call. By convention, node classes that have CssMetaData will implement a static method getClassCssMetaData() and it is customary to have getCssMetaData() simply return getClassCssMetaData(). The purpose of getClassCssMetaData() is to allow sub-classes to easily include the CssMetaData of some ancestor.

    The StyleablePropertyFactory greatly simplifies creating a StyleableProperty and its corresponding CssMetaData.

    This example is a typical implementation. 

    
 private DoubleProperty gapProperty = new StyleableDoubleProperty(0) {
     @Override
      public CssMetaData<MyWidget,Number> getCssMetaData() {
          return GAP_META_DATA;
      }

      @Override
      public Object getBean() {
          return MyWidget.this;
      }

      @Override
      public String getName() {
          return "gap";
      }
 };

 private static final CssMetaData GAP_META_DATA =
     new CssMetaData<MyWidget,Number>("-my-gap", StyleConverter.getSizeConverter(), 0d) {

        @Override
        public boolean isSettable(MyWidget node) {
            return node.gapProperty == null || !node.gapProperty.isBound();
        }

        @Override
        public StyleableProperty<Number> getStyleableProperty(MyWidget node) {
            return (StyleableProperty<Number>)node.gapProperty;
        }
 };

 private static final List<CssMetaData<? extends Node, ?>> cssMetaDataList;
 static {
     List<CssMetaData<? extends Node, ?>> temp =
         new ArrayList<CssMetaData<? extends Node, ?>>(Control.getClassCssMetaData());
     temp.add(GAP_META_DATA);
     cssMetaDataList = Collections.unmodifiableList(temp);
 }

 public static List<CssMetaData<? extends Node, ?>> getClassCssMetaData() {
     return cssMetaDataList;
 }

 @Override
 public List<CssMetaData<? extends Node, ?>> getCssMetaData() {
     return getClassCssMetaData();
 }
    Since:
    JavaFX 8.0
    See Also:
    StyleablePropertyFactory

    • Constructor Detail

      • CssMetaData

        protected CssMetaData​(String property,
                      StyleConverter<?,V> converter,
                      V initialValue,
                      boolean inherits,
                      List<CssMetaData<? extends Styleable,?>> subProperties)
        Construct a CssMetaData with the given parameters and no sub-properties.
        Parameters:
        property - the CSS property
        converter - the StyleConverter used to convert the CSS parsed value to a Java object.
        initialValue - The initial or default value of the corresponding StyleableProperty
        inherits - true if this property uses CSS inheritance
        subProperties - the sub-properties of this property. For example, the -fx-font property has the sub-properties -fx-font-family, -fx-font-size, -fx-font-weight, and -fx-font-style.

      • CssMetaData

        protected CssMetaData​(String property,
                      StyleConverter<?,V> converter,
                      V initialValue,
                      boolean inherits)
        Construct a CssMetaData with the given parameters and no sub-properties.
        Parameters:
        property - the CSS property
        converter - the StyleConverter used to convert the CSS parsed value to a Java object.
        initialValue - The initial or default value of the corresponding StyleableProperty
        inherits - true if this property uses CSS inheritance

      • CssMetaData

        protected CssMetaData​(String property,
                      StyleConverter<?,V> converter,
                      V initialValue)
        Construct a CssMetaData with the given parameters, inherit set to false and no sub-properties.
        Parameters:
        property - the CSS property
        converter - the StyleConverter used to convert the CSS parsed value to a Java object.
        initialValue - The initial or default value of the corresponding StyleableProperty

      • CssMetaData

        protected CssMetaData​(String property,
                      StyleConverter<?,V> converter)
        Construct a CssMetaData with the given parameters, initialValue is null, inherit is set to false, and no sub-properties.
        Parameters:
        property - the CSS property
        converter - the StyleConverter used to convert the CSS parsed value to a Java object.

    • Method Detail

      • isSettable

        public abstract boolean isSettable​(S styleable)
        Check to see if the corresponding property on the given Node is settable. This method is called before any styles are looked up for the given property. It is abstract so that the code can check if the property is settable without expanding the property. Generally, the property is settable if it is not null or is not bound.
        Parameters:
        styleable - The Styleable on which the property value is being set
        Returns:
        true if the property can be set.

      • getStyleableProperty

        public abstract StyleableProperty<V> getStyleableProperty​(S styleable)
        Return the corresponding StyleableProperty for the given Node. Note that calling this method will cause the property to be expanded.
        Parameters:
        styleable - The Styleable for which the property is returned
        Returns:
        The StyleableProperty corresponding to this CssMetaData for the given Styleable

      • getProperty

        public final String getProperty()
        Returns:
        the CSS property name

      • getConverter

        public final StyleConverter<?,V> getConverter()
        Returns:
        The CSS converter that handles conversion from a CSS value to a Java Object

      • getInitialValue

        public V getInitialValue​(S styleable)
        The initial value of a CssMetaData corresponds to the default value of the StyleableProperty in code. For example, the default value of Shape.fill is Color.BLACK and the initialValue of Shape.StyleableProperties.FILL is also Color.BLACK.

        There may be exceptions to this, however. The initialValue may depend on the state of the Node. A ScrollBar has a default orientation of horizontal. If the ScrollBar is vertical, however, this method should return Orientation.VERTICAL. Otherwise, a vertical ScrollBar would be incorrectly set to a horizontal ScrollBar when the initial value is applied.

        Parameters:
        styleable - the styleable
        Returns:
        The initial value of the property, possibly null

      • getSubProperties

        public final List<CssMetaData<? extends Styleable,?>> getSubProperties()
        The sub-properties refers to the constituent properties of this property, if any. For example, "-fx-font-weight" is sub-property of "-fx-font".
        Returns:
        the list of sub-properties

      • isInherits

        public final boolean isInherits()
        If true, the value of this property is the same as the parent's computed value of this property.
        Returns:
        false by default unless inherits is true
        See Also:
        CSS Inheritance

      • equals

        public boolean equals​(Object obj)
        Two CssMetaData objects are considered to be equal if their property values are equal.
        Overrides:
        equals in class Object
        Parameters:
        obj - the reference object with which to compare.
        Returns:
        true if the obj is equaled, false otherwise
        See Also:
        Object.hashCode(), HashMap