Module javafx.graphics
Package javafx.scene

Class Group

  • All Implemented Interfaces:
    Styleable, EventTarget

    @DefaultProperty("children")
public class Group
extends Parent
    A Group node contains an ObservableList of children that are rendered in order whenever this node is rendered.

    A Group will take on the collective bounds of its children and is not directly resizable.

    Any transform, effect, or state applied to a Group will be applied to all children of that group. Such transforms and effects will NOT be included in this Group's layout bounds, however if transforms and effects are set directly on children of this Group, those will be included in this Group's layout bounds.

    By default, a Group will "auto-size" its managed resizable children to their preferred sizes during the layout pass to ensure that Regions and Controls are sized properly as their state changes. If an application needs to disable this auto-sizing behavior, then it should set autoSizeChildren to false and understand that if the preferred size of the children change, they will not automatically resize (so buyer beware!).

    Group Example:

    import javafx.scene.*;
import javafx.scene.paint.*;
import javafx.scene.shape.*;
import java.lang.Math;

Group g = new Group();
for (int i = 0; i < 5; i++) {
    Rectangle r = new Rectangle();
    r.setY(i * 20);
    r.setWidth(100);
    r.setHeight(10);
    r.setFill(Color.RED);
    g.getChildren().add(r);
}
    Since:
    JavaFX 2.0

    • Property Detail

      • autoSizeChildren

        public final BooleanProperty autoSizeChildrenProperty
        Controls whether or not this Group will automatically resize any managed resizable children to their preferred sizes during the layout pass. If set to false, then the application is responsible for setting the size of this Group's resizable children, otherwise such nodes may end up with a zero width/height and will not be visible. This variable has no effect on content nodes which are not resizable (Shape, Text, etc).
        Default value:
        true
        See Also:
        isAutoSizeChildren(), setAutoSizeChildren(boolean)

    • Constructor Detail

      • Group

        public Group​()
        Constructs a group.

      • Group

        public Group​(Node... children)
        Constructs a group consisting of children.
        Parameters:
        children - children.

      • Group

        public Group​(Collection<Node> children)
        Constructs a group consisting of the given children.
        Parameters:
        children - children of the group
        Throws:
        NullPointerException - if the specified collection is null
        Since:
        JavaFX 8.0

    • Method Detail

      • setAutoSizeChildren

        public final void setAutoSizeChildren​(boolean value)
        Sets the value of the property autoSizeChildren.
        Property description:
        Controls whether or not this Group will automatically resize any managed resizable children to their preferred sizes during the layout pass. If set to false, then the application is responsible for setting the size of this Group's resizable children, otherwise such nodes may end up with a zero width/height and will not be visible. This variable has no effect on content nodes which are not resizable (Shape, Text, etc).
        Default value:
        true

      • isAutoSizeChildren

        public final boolean isAutoSizeChildren​()
        Gets the value of the property autoSizeChildren.
        Property description:
        Controls whether or not this Group will automatically resize any managed resizable children to their preferred sizes during the layout pass. If set to false, then the application is responsible for setting the size of this Group's resizable children, otherwise such nodes may end up with a zero width/height and will not be visible. This variable has no effect on content nodes which are not resizable (Shape, Text, etc).
        Default value:
        true

      • autoSizeChildrenProperty

        public final BooleanProperty autoSizeChildrenProperty​()
        Controls whether or not this Group will automatically resize any managed resizable children to their preferred sizes during the layout pass. If set to false, then the application is responsible for setting the size of this Group's resizable children, otherwise such nodes may end up with a zero width/height and will not be visible. This variable has no effect on content nodes which are not resizable (Shape, Text, etc).
        Default value:
        true
        See Also:
        isAutoSizeChildren(), setAutoSizeChildren(boolean)

      • getChildren

        public ObservableList<Node> getChildren​()
        Gets the list of children of this Group.
        Overrides:
        getChildren in class Parent
        Returns:
        the list of children of this Group.

      • prefWidth

        public double prefWidth​(double height)
        Group defines the preferred width as simply being the width of its layout bounds, which in turn is simply the sum of the positions and widths of all of its children. That is, the preferred width is the one that it is at, because a Group cannot be resized. Note: as the layout bounds in autosize Group depend on the Group to be already laid-out, this call will do the layout of the Group if necessary.
        Overrides:
        prefWidth in class Parent
        Parameters:
        height - This parameter is ignored by Group
        Returns:
        The layout bounds width
        See Also:
        Node.isResizable(), Node.getContentBias(), Node.autosize()

      • prefHeight

        public double prefHeight​(double width)
        Group defines the preferred height as simply being the height of its layout bounds, which in turn is simply the sum of the positions and heights of all of its children. That is, the preferred height is the one that it is at, because a Group cannot be resized. Note: as the layout bounds in autosize Group depend on the Group to be already laid-out, this call will do the layout of the Group if necessary.
        Overrides:
        prefHeight in class Parent
        Parameters:
        width - This parameter is ignored by Group
        Returns:
        The layout bounds height
        See Also:
        Node.getContentBias(), Node.autosize()

      • minHeight

        public double minHeight​(double width)
        Description copied from class: Node
        Returns the node's minimum height for use in layout calculations. If the node is resizable, its parent should not resize its height any smaller than this value. If the node is not resizable, returns its layoutBounds height.

        Layout code which calls this method should first check the content-bias of the node. If the node has a horizontal content-bias, then callers should pass in a width value that the minimum height should be based on. If the node has either a vertical or null content-bias, then the caller should pass in -1.

        Node subclasses with a horizontal content-bias should honor the width parameter whether -1 or a positive value. All other subclasses may ignore the width parameter (which will likely be -1).

        If Node's Node.maxHeight(double) is lower than this number, minHeight takes precedence. This means the Node should never be resized below minHeight.

        Overrides:
        minHeight in class Parent
        Parameters:
        width - the width that should be used if minimum height depends on it
        Returns:
        the minimum height that the node should be resized to during layout The result will never be NaN, nor will it ever be negative.
        See Also:
        Node.isResizable(), Node.getContentBias()

      • minWidth

        public double minWidth​(double height)
        Description copied from class: Node
        Returns the node's minimum width for use in layout calculations. If the node is resizable, its parent should not resize its width any smaller than this value. If the node is not resizable, returns its layoutBounds width.

        Layout code which calls this method should first check the content-bias of the node. If the node has a vertical content-bias, then callers should pass in a height value that the minimum width should be based on. If the node has either a horizontal or null content-bias, then the caller should pass in -1.

        Node subclasses with a vertical content-bias should honor the height parameter whether -1 or a positive value. All other subclasses may ignore the height parameter (which will likely be -1).

        If Node's Node.maxWidth(double) is lower than this number, minWidth takes precedence. This means the Node should never be resized below minWidth.

        Overrides:
        minWidth in class Parent
        Parameters:
        height - the height that should be used if minimum width depends on it
        Returns:
        the minimum width that the node should be resized to during layout. The result will never be NaN, nor will it ever be negative.
        See Also:
        Node.isResizable(), Node.getContentBias()

      • layoutChildren

        protected void layoutChildren​()
        Group implements layoutChildren such that each child is resized to its preferred size, if the child is resizable. Non-resizable children are simply left alone. If autoSizeChildren is false, then Group does nothing in this method.
        Overrides:
        layoutChildren in class Parent