Module javafx.controls
Package javafx.scene.control.skin

## Class ComboBoxBaseSkin<T>

- java.lang.Object
- - javafx.scene.control.SkinBase<ComboBoxBase<T>>
  - - javafx.scene.control.skin.ComboBoxBaseSkin<T>

- Type Parameters:
    `T` - The type of the ComboBox-like control.
  All Implemented Interfaces:
    `Skin<ComboBoxBase<T>>`
  Direct Known Subclasses:
    `ComboBoxPopupControl`

      public abstract class ComboBoxBaseSkin<T>
      extends SkinBase<ComboBoxBase<T>>

  An abstract class intended to be used as the base skin for ComboBox-like controls that are based on `ComboBoxBase`. Most users of this skin class would be well-advised to also look at `ComboBoxPopupControl` for additional useful API.
  Since:
    9
  See Also:
    `ComboBoxBase`, `ComboBoxPopupControl`

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `ComboBoxBaseSkin​(ComboBoxBase<T> control)` | Creates a new instance of ComboBoxBaseSkin, although note that this instance does not handle any behavior / input mappings - this needs to be handled appropriately by subclasses.

  - ### Method Summary

    Modifier and Type | Method | Description
    --- | --- | ---
    `protected double` | `computeBaselineOffset​(double topInset, double rightInset, double bottomInset, double leftInset)` | Calculates the baseline offset based on the first managed child.
    `protected double` | `computeMaxHeight​(double width, double topInset, double rightInset, double bottomInset, double leftInset)` | Computes the maximum allowable height of the Skin, based on the provided width.
    `protected double` | `computeMaxWidth​(double height, double topInset, double rightInset, double bottomInset, double leftInset)` | Computes the maximum allowable width of the Skin, based on the provided height.
    `protected double` | `computePrefHeight​(double width, double topInset, double rightInset, double bottomInset, double leftInset)` | Calculates the preferred height of this `SkinBase`.
    `protected double` | `computePrefWidth​(double height, double topInset, double rightInset, double bottomInset, double leftInset)` | Calculates the preferred width of this `SkinBase`.
    `abstract Node` | `getDisplayNode()` | This method should return a Node that will be positioned within the ComboBox 'button' area.
    `abstract void` | `hide()` | This method will be called when the ComboBox popup should be hidden.
    `protected void` | `layoutChildren​(double x, double y, double w, double h)` | Called during the layout pass of the scenegraph.
    `abstract void` | `show()` | This method will be called when the ComboBox popup should be displayed.

    - ### Methods inherited from class javafx.scene.control.SkinBase

      `computeMinHeight, computeMinWidth, consumeMouseEvents, dispose, executeAccessibleAction, getChildren, getClassCssMetaData, getCssMetaData, getNode, getSkinnable, layoutInArea, layoutInArea, layoutInArea, positionInArea, positionInArea, pseudoClassStateChanged, queryAccessibleAttribute, registerChangeListener, snappedBottomInset, snappedLeftInset, snappedRightInset, snappedTopInset, snapPosition, snapPositionX, snapPositionY, snapSize, snapSizeX, snapSizeY, snapSpace, snapSpaceX, snapSpaceY, unregisterChangeListeners`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### ComboBoxBaseSkin

          public ComboBoxBaseSkin​(ComboBoxBase<T> control)

      Creates a new instance of ComboBoxBaseSkin, although note that this instance does not handle any behavior / input mappings - this needs to be handled appropriately by subclasses.
      Parameters:
        `control` - The control that this skin should be installed onto.

  - ### Method Detail

    - #### getDisplayNode

          public abstract Node getDisplayNode()

      This method should return a Node that will be positioned within the ComboBox 'button' area.
      Returns:
        the node that will be positioned within the ComboBox 'button' area

    - #### show

          public abstract void show()

      This method will be called when the ComboBox popup should be displayed. It is up to specific skin implementations to determine how this is handled.

    - #### hide

          public abstract void hide()

      This method will be called when the ComboBox popup should be hidden. It is up to specific skin implementations to determine how this is handled.

    - #### layoutChildren

          protected void layoutChildren​(double x,
                                        double y,
                                        double w,
                                        double h)

      Called during the layout pass of the scenegraph.
      Overrides:
        `layoutChildren` in class `SkinBase<ComboBoxBase<T>>`
      Parameters:
        `x` - the x position
        `y` - the y position
        `w` - the width
        `h` - the height

    - #### computePrefWidth

          protected double computePrefWidth​(double height,
                                            double topInset,
                                            double rightInset,
                                            double bottomInset,
                                            double leftInset)

      Calculates the preferred width of this `SkinBase`. The default implementation calculates this width as the width of the area occupied by its managed children when they are positioned at their current positions at their preferred widths.
      Overrides:
        `computePrefWidth` in class `SkinBase<ComboBoxBase<T>>`
      Parameters:
        `height` - the height that should be used if preferred width depends on it
        `topInset` - the pixel snapped top inset
        `rightInset` - the pixel snapped right inset
        `bottomInset` - the pixel snapped bottom inset
        `leftInset` - the pixel snapped left inset
      Returns:
        the calculated preferred width

    - #### computePrefHeight

          protected double computePrefHeight​(double width,
                                             double topInset,
                                             double rightInset,
                                             double bottomInset,
                                             double leftInset)

      Calculates the preferred height of this `SkinBase`. The default implementation calculates this height as the height of the area occupied by its managed children when they are positioned at their current positions at their preferred heights.
      Overrides:
        `computePrefHeight` in class `SkinBase<ComboBoxBase<T>>`
      Parameters:
        `width` - the width that should be used if preferred height depends on it
        `topInset` - the pixel snapped top inset
        `rightInset` - the pixel snapped right inset
        `bottomInset` - the pixel snapped bottom inset
        `leftInset` - the pixel snapped left inset
      Returns:
        the calculated preferred height

    - #### computeMaxWidth

          protected double computeMaxWidth​(double height,
                                           double topInset,
                                           double rightInset,
                                           double bottomInset,
                                           double leftInset)

      Computes the maximum allowable width of the Skin, based on the provided height.
      Overrides:
        `computeMaxWidth` in class `SkinBase<ComboBoxBase<T>>`
      Parameters:
        `height` - The height of the Skin, in case this value might dictate the maximum width.
        `topInset` - the pixel snapped top inset
        `rightInset` - the pixel snapped right inset
        `bottomInset` - the pixel snapped bottom inset
        `leftInset` - the pixel snapped left inset
      Returns:
        A double representing the maximum width of this Skin.

    - #### computeMaxHeight

          protected double computeMaxHeight​(double width,
                                            double topInset,
                                            double rightInset,
                                            double bottomInset,
                                            double leftInset)

      Computes the maximum allowable height of the Skin, based on the provided width.
      Overrides:
        `computeMaxHeight` in class `SkinBase<ComboBoxBase<T>>`
      Parameters:
        `width` - The width of the Skin, in case this value might dictate the maximum height.
        `topInset` - the pixel snapped top inset
        `rightInset` - the pixel snapped right inset
        `bottomInset` - the pixel snapped bottom inset
        `leftInset` - the pixel snapped left inset
      Returns:
        A double representing the maximum height of this Skin.

    - #### computeBaselineOffset

          protected double computeBaselineOffset​(double topInset,
                                                 double rightInset,
                                                 double bottomInset,
                                                 double leftInset)

      Calculates the baseline offset based on the first managed child. If there is no such child, returns `Node.getBaselineOffset()`.
      Overrides:
        `computeBaselineOffset` in class `SkinBase<ComboBoxBase<T>>`
      Parameters:
        `topInset` - the pixel snapped top inset
        `rightInset` - the pixel snapped right inset
        `bottomInset` - the pixel snapped bottom inset
        `leftInset` - the pixel snapped left inset
      Returns:
        baseline offset