Module javafx.graphics
Package javafx.scene.layout

Class AnchorPane

java.lang.Object
javafx.scene.Node
javafx.scene.Parent
javafx.scene.layout.Region
javafx.scene.layout.Pane
javafx.scene.layout.AnchorPane
All Implemented Interfaces:
Styleable, EventTarget
public class AnchorPane
extends Pane
AnchorPane allows the edges of child nodes to be anchored to an offset from the anchor pane's edges. If the anchor pane has a border and/or padding set, the offsets will be measured from the inside edge of those insets.

AnchorPane lays out each managed child regardless of the child's visible property value; unmanaged children are ignored for all layout calculations.

AnchorPanes may be styled with backgrounds and borders using CSS. See Region superclass for details.

Anchor Constraints

The application sets anchor constraints on each child to configure the anchors on one or more sides. If a child is anchored on opposite sides (and is resizable), the anchor pane will resize it to maintain both offsets, otherwise the anchor pane will resize it to its preferred size. If in the former case (anchored on opposite sides) and the child is not resizable, then only the top/left anchor will be honored. AnchorPane provides a static method for setting each anchor constraint.

AnchorPane Constraint Table
ConstraintTypeDescription
topAnchordoubledistance from the anchor pane's top insets to the child's top edge.
leftAnchordoubledistance from the anchor pane's left insets to the child's left edge.
bottomAnchordoubledistance from the anchor pane's bottom insets to the child's bottom edge.
rightAnchordoubledistance from the anchor pane's right insets to the child's right edge.

AnchorPane Example: 

     AnchorPane anchorPane = new AnchorPane();
     // List should stretch as anchorPane is resized
     ListView list = new ListView();
     AnchorPane.setTopAnchor(list, 10.0);
     AnchorPane.setLeftAnchor(list, 10.0);
     AnchorPane.setRightAnchor(list, 65.0);
     // Button will float on right edge
     Button button = new Button("Add");
     AnchorPane.setTopAnchor(button, 10.0);
     AnchorPane.setRightAnchor(button, 10.0);
     anchorPane.getChildren().addAll(list, button);

Resizable Range

An anchor pane's parent will resize the anchor pane within the anchor pane's resizable range during layout. By default the anchor pane computes this range based on its content as outlined in the table below.

AnchorPane Resize Table
widthheight
minimum left/right insets plus width required to display children anchored at left/right with at least their min widths top/bottom insets plus height required to display children anchored at top/bottom with at least their min heights
preferred left/right insets plus width required to display children anchored at left/right with at least their pref widths top/bottom insets plus height required to display children anchored at top/bottom with at least their pref heights
maximum Double.MAX_VALUEDouble.MAX_VALUE

An anchor pane's unbounded maximum width and height are an indication to the parent that it may be resized beyond its preferred size to fill whatever space is assigned to it.

AnchorPane provides properties for setting the size range directly. These properties default to the sentinel value Region.USE_COMPUTED_SIZE, however the application may set them to other values as needed: 

     anchorPane.setPrefSize(300, 300);
Applications may restore the computed values by setting these properties back to Region.USE_COMPUTED_SIZE.

AnchorPane does not clip its content by default, so it is possible that children's bounds may extend outside its own bounds if the anchor pane is resized smaller than its preferred size.

Since:
JavaFX 2.0

  • Constructor Details

    • AnchorPane

      public AnchorPane()
      Creates an AnchorPane layout.

    • AnchorPane

      public AnchorPane​(Node... children)
      Creates an AnchorPane layout with the given children.
      Parameters:
      children - The initial set of children for this pane.
      Since:
      JavaFX 8.0

  • Method Details

    • setTopAnchor

      public static void setTopAnchor​(Node child, Double value)
      Sets the top anchor for the child when contained by an anchor pane. If set, the anchor pane will maintain the child's size and position so that it's top is always offset by that amount from the anchor pane's top content edge. Setting the value to null will remove the constraint.
      Parameters:
      child - the child node of an anchor pane
      value - the offset from the top of the anchor pane

    • getTopAnchor

      public static Double getTopAnchor​(Node child)
      Returns the child's top anchor constraint if set.
      Parameters:
      child - the child node of an anchor pane
      Returns:
      the offset from the top of the anchor pane or null if no top anchor was set

    • setLeftAnchor

      public static void setLeftAnchor​(Node child, Double value)
      Sets the left anchor for the child when contained by an anchor pane. If set, the anchor pane will maintain the child's size and position so that it's left is always offset by that amount from the anchor pane's left content edge. Setting the value to null will remove the constraint.
      Parameters:
      child - the child node of an anchor pane
      value - the offset from the left of the anchor pane

    • getLeftAnchor

      public static Double getLeftAnchor​(Node child)
      Returns the child's left anchor constraint if set.
      Parameters:
      child - the child node of an anchor pane
      Returns:
      the offset from the left of the anchor pane or null if no left anchor was set

    • setBottomAnchor

      public static void setBottomAnchor​(Node child, Double value)
      Sets the bottom anchor for the child when contained by an anchor pane. If set, the anchor pane will maintain the child's size and position so that it's bottom is always offset by that amount from the anchor pane's bottom content edge. Setting the value to null will remove the constraint.
      Parameters:
      child - the child node of an anchor pane
      value - the offset from the bottom of the anchor pane

    • getBottomAnchor

      public static Double getBottomAnchor​(Node child)
      Returns the child's bottom anchor constraint if set.
      Parameters:
      child - the child node of an anchor pane
      Returns:
      the offset from the bottom of the anchor pane or null if no bottom anchor was set

    • setRightAnchor

      public static void setRightAnchor​(Node child, Double value)
      Sets the right anchor for the child when contained by an anchor pane. If set, the anchor pane will maintain the child's size and position so that it's right is always offset by that amount from the anchor pane's right content edge. Setting the value to null will remove the constraint.
      Parameters:
      child - the child node of an anchor pane
      value - the offset from the right of the anchor pane

    • getRightAnchor

      public static Double getRightAnchor​(Node child)
      Returns the child's right anchor constraint if set.
      Parameters:
      child - the child node of an anchor pane
      Returns:
      the offset from the right of the anchor pane or null if no right anchor was set

    • clearConstraints

      public static void clearConstraints​(Node child)
      Removes all anchor pane constraints from the child node.
      Parameters:
      child - the child node

    • computeMinWidth

      protected double computeMinWidth​(double height)
      Description copied from class: Region
      Computes the minimum width of this region. Returns the sum of the left and right insets by default. region subclasses should override this method to return an appropriate value based on their content and layout strategy. If the subclass doesn't have a VERTICAL content bias, then the height parameter can be ignored.
      Overrides:
      computeMinWidth in class Region
      Parameters:
      height - the height that should be used if min width depends on it
      Returns:
      the computed minimum width of this region

    • computeMinHeight

      protected double computeMinHeight​(double width)
      Description copied from class: Region
      Computes the minimum height of this region. Returns the sum of the top and bottom insets by default. Region subclasses should override this method to return an appropriate value based on their content and layout strategy. If the subclass doesn't have a HORIZONTAL content bias, then the width parameter can be ignored.
      Overrides:
      computeMinHeight in class Region
      Parameters:
      width - the width that should be used if min height depends on it
      Returns:
      the computed minimum height for this region

    • computePrefWidth

      protected double computePrefWidth​(double height)
      Description copied from class: Region
      Computes the preferred width of this region for the given height. Region subclasses should override this method to return an appropriate value based on their content and layout strategy. If the subclass doesn't have a VERTICAL content bias, then the height parameter can be ignored.
      Overrides:
      computePrefWidth in class Region
      Parameters:
      height - the height that should be used if preferred width depends on it
      Returns:
      the computed preferred width for this region

    • computePrefHeight

      protected double computePrefHeight​(double width)
      Description copied from class: Region
      Computes the preferred height of this region for the given width; Region subclasses should override this method to return an appropriate value based on their content and layout strategy. If the subclass doesn't have a HORIZONTAL content bias, then the width parameter can be ignored.
      Overrides:
      computePrefHeight in class Region
      Parameters:
      width - the width that should be used if preferred height depends on it
      Returns:
      the computed preferred height for this region

    • layoutChildren

      protected void layoutChildren()
      Description copied from class: Parent
      Invoked during the layout pass to layout the children in this Parent. By default it will only set the size of managed, resizable content to their preferred sizes and does not do any node positioning.

      Subclasses should override this function to layout content as needed.

      Overrides:
      layoutChildren in class Parent