Class GroupLayout

java.lang.Object
com.codename1.ui.layouts.Layout
com.codename1.ui.layouts.GroupLayout
public class GroupLayout extends Layout

GroupLayout is a LayoutManager that hierarchically groups components to achieve common, and not so common, layouts. Grouping is done by instances of the Group class. GroupLayout supports two types of groups:

Sequential:A sequential group positions its child elements sequentially, one after another. Parallel:A parallel group positions its child elements in the same space on top of each other. Parallel groups can also align the child elements along their baseline.

Each Group can contain any number of child groups, Components or gaps. GroupLayout treats each axis independently. That is, there is a group representing the horizontal axis, and a separate group representing the vertical axis. The horizontal group is responsible for setting the x and width of its contents, where as the vertical group is responsible for setting the y and height of its contents.

The following code builds a simple layout consisting of two labels in one column, followed by two textfields in the next column:

  Container panel = ...;
  GroupLayout layout = new GroupLayout(panel);
  panel.setLayout(layout);
  layout.setAutocreateGaps(true);
  layout.setAutocreateContainerGaps(true);
  GroupLayout.SequentialGroup hGroup = layout.createSequentialGroup();
  hGroup.add(layout.createParallelGroup().add(label1).add(label2)).
         add(layout.createParallelGroup().add(tf1).add(tf2));
  layout.setHorizontalGroup(hGroup);
  GroupLayout.SequentialGroup vGroup = layout.createSequentialGroup();
  vGroup.add(layout.createParallelGroup(GroupLayout.BASELINE).add(label1).add(tf1)).
         add(layout.createParallelGroup(GroupLayout.BASELINE).add(label2).add(tf2));
  layout.setVerticalGroup(vGroup);

This layout consists of the following:

  • The horizontal axis consists of a sequential group containing two parallel groups. The first parallel group consists of the labels, with the second parallel group consisting of the text fields.

  • The vertical axis similarly consists of a sequential group containing two parallel groups. The parallel groups align their contents along the baseline. The first parallel group consists of the first label and text field, and the second group consists of the second label and text field.

There are a couple of things to notice in this code:

  • You need not explicitly add the components to the container, this is indirectly done by using one of the add methods.

  • The various add methods of Groups return themselves. This allows for easy chaining of invocations. For example, group.add(label1).add(label2); is equivalent to group.add(label1);group.add(label2);.

  • There are no public constructors for the Groups, instead use the create methods of GroupLayout.

GroupLayout offer the ability to automatically insert the appropriate gap between components. This can be turned on using the setAutocreateGaps() method. Similarly you can use the setAutocreateContainerGaps() method to insert gaps between the components and the container.

  • Field Details

    • NORTH

      public static final int NORTH
      Compass-direction North (up).
      See Also:

    • EAST

      public static final int EAST
      Compass-direction east (right).
      See Also:

    • SOUTH

      public static final int SOUTH
      Compass-direction south (down).
      See Also:

    • WEST

      public static final int WEST
      Compass-direction west (left).
      See Also:

    • HORIZONTAL

      public static final int HORIZONTAL

      Possible argument when linking sizes of components. Specifies the the two component should share the same size along the horizontal axis.

      See also
      • #linkSize(Component[], int)
      See Also:

    • VERTICAL

      public static final int VERTICAL

      Possible argument when linking sizes of components. Specifies the the two component should share the same size along the vertical axis.

      See also
      • #linkSize(Component[], int)
      See Also:

    • LEADING

      public static final int LEADING

      Possible alignment type. Indicates the elements should be aligned to the origin. For the horizontal axis with a left to right orientation this means aligned to the left.

      See also
      • #createParallelGroup(int)
      See Also:

    • TRAILING

      public static final int TRAILING

      Possible alignment type. Indicates the elements should be aligned to the end. For the horizontal axis with a left to right orientation this means aligned to the right.

      See also
      • #createParallelGroup(int)
      See Also:

    • CENTER

      public static final int CENTER

      Possible alignment type. Indicates the elements should centered in the spaced provided.

      See also
      • #createParallelGroup(int)
      See Also:

    • BASELINE

      public static final int BASELINE

      Possible alignment type. Indicates the elements should aligned along their baseline.

      See also
      • #createParallelGroup(int)
      See Also:

    • DEFAULT_SIZE

      public static final int DEFAULT_SIZE
      Possible value for the add methods that takes a Component. Indicates the size from the component should be used.
      See Also:

    • PREFERRED_SIZE

      public static final int PREFERRED_SIZE
      Possible value for the add methods that takes a Component. Indicates the preferred size should be used.
      See Also:

  • Constructor Details

    • GroupLayout

      public GroupLayout(Container host)

      Creates a GroupLayout for the specified Container.

      Parameters
      • host: the Container to layout
      Throws
      • IllegalArgumentException: if host is null

  • Method Details

    • getHonorsVisibility

      public boolean getHonorsVisibility()

      Returns whether component visibility is considered when sizing and positioning components.

      Returns
      Returns:
      whether component visibility is considered when sizing and positioning components

    • setHonorsVisibility

      public void setHonorsVisibility(boolean honorsVisibility)

      Sets whether component visibility is considered when sizing and positioning components. A value of true indicates that non-visible components should not be treated as part of the layout. A value of false indicates that components should be positioned and sized regardless of visibility.

      A value of false is useful when the visibility of components is dynamically adjusted and you don't want surrounding components and the sizing to change.

      The specified value is used for components that do not have an explicit visibility specified.

      The default is true.

      Parameters
      • honorsVisibility: @param honorsVisibility whether component visibility is considered when sizing and positioning components
      See also
      • #setHonorsVisibility(Component, Boolean)

    • setHonorsVisibility

      public void setHonorsVisibility(Component component, Boolean honorsVisibility)

      Sets whether the component's visibility is considered for sizing and positioning. A value of Boolean.TRUE indicates that if component is not visible it should not be treated as part of the layout. A value of false indicates that component is positioned and sized regardless of it's visibility. A value of null indicates the value specified by the single argument method setHonorsVisibility should be used.

      If component is not a child of the Container this GroupLayout is managing, it will be added to the Container.

      Parameters

      • component: the component

      • honorsVisibility: @param honorsVisibility whether component's visibility should be considered for sizing and positioning

      Throws
      • IllegalArgumentException: if component is null
      See also
      • #setHonorsVisibility(boolean)

    • toString

      public String toString()

      Returns a textual description of this GroupLayout. The return value is intended for debugging purposes only.

      Returns

      textual description of this GroupLayout

      Overrides:
      toString in class Object

    • getAutocreateGaps

      public boolean getAutocreateGaps()

      Returns true if gaps between components are automatically be created.

      Returns

      true if gaps between components should automatically be created

    • setAutocreateGaps

      public void setAutocreateGaps(boolean autocreatePadding)

      Sets whether or not a gap between components should automatically be created. For example, if this is true and you add two components to a SequentialGroup a gap between the two will automatically be created. The default is false.

      Parameters
      • autocreatePadding: @param autocreatePadding whether or not to automatically created a gap between components and the container

    • getAutocreateContainerGaps

      public boolean getAutocreateContainerGaps()

      Returns whether or not gaps between the container and the first/last components should automatically be created. The default is false.

      Returns
      Returns:
      whether or not the gaps between the container and the first/last components should automatically be created

    • setAutocreateContainerGaps

      public void setAutocreateContainerGaps(boolean autocreatePadding)

      Sets whether or not gaps between the container and the first/last components should automatically be created. The default is false.

      Parameters
      • autocreatePadding: @param autocreatePadding whether or not to automatically create gaps between the container and first/last components.

    • getHorizontalGroup

      public GroupLayout.Group getHorizontalGroup()

      Returns the Group that is responsible for layout along the horizontal axis.

      Returns
      Returns:
      ParallelGroup responsible for layout along the horizontal axis.

    • setHorizontalGroup

      public void setHorizontalGroup(GroupLayout.Group group)

      Sets the Group that is responsible for layout along the horizontal axis.

      Parameters
      • group: @param group Group responsible for layout along the horizontal axis
      Throws
      • IllegalArgumentException: if group is null

    • getVerticalGroup

      public GroupLayout.Group getVerticalGroup()

      Returns the ParallelGroup that is responsible for layout along the vertical axis.

      Returns
      Returns:
      ParallelGroup responsible for layout along the vertical axis.

    • setVerticalGroup

      public void setVerticalGroup(GroupLayout.Group group)

      Sets the Group that is responsible for layout along the vertical axis.

      Parameters
      • group: @param group Group responsible for layout along the vertical axis.
      Throws
      • IllegalArgumentException: if group is null.

    • createSequentialGroup

      public GroupLayout.SequentialGroup createSequentialGroup()

      Creates and returns a SequentialGroup.

      Returns

      a new SequentialGroup

    • createParallelGroup

      public GroupLayout.ParallelGroup createParallelGroup()

      Creates and returns a ParallelGroup with a LEADING alignment. This is a cover method for the more general createParallelGroup(int) method.

      Returns

      a new ParallelGroup

      See also
      • #createParallelGroup(int)

    • createParallelGroup

      public GroupLayout.ParallelGroup createParallelGroup(int alignment)

      Creates and returns an ParallelGroup. The alignment specifies how children elements should be positioned when the the parallel group is given more space than necessary. For example, if a ParallelGroup with an alignment of TRAILING is given 100 pixels and a child only needs 50 pixels, the child will be positioned at the position 50.

      Parameters
      • alignment: @param alignment alignment for the elements of the Group, one of LEADING, TRAILING, CENTER or BASELINE.
      Returns

      a new ParallelGroup

      Throws
      • IllegalArgumentException: @throws IllegalArgumentException if alignment is not one of LEADING, TRAILING, CENTER or BASELINE

    • createParallelGroup

      public GroupLayout.ParallelGroup createParallelGroup(int alignment, boolean resizable)

      Creates and returns an ParallelGroup. The alignment specifies how children elements should be positioned when the the parallel group is given more space than necessary. For example, if a ParallelGroup with an alignment of TRAILING is given 100 pixels and a child only needs 50 pixels, the child will be positioned at the position 50.

      Parameters

      • alignment: @param alignment alignment for the elements of the Group, one of LEADING, TRAILING, CENTER or BASELINE.

      • resizable: @param resizable whether or not the group is resizable. If the group is not resizable the min/max size will be the same as the preferred.

      Returns

      a new ParallelGroup

      Throws
      • IllegalArgumentException: @throws IllegalArgumentException if alignment is not one of LEADING, TRAILING, CENTER or BASELINE

    • createBaselineGroup

      public GroupLayout.ParallelGroup createBaselineGroup(boolean resizable, boolean anchorBaselineToTop)

      Creates and returns a ParallelGroup that aligns it's elements along the baseline.

      Parameters

      • resizable: whether the group is resizable

      • anchorBaselineToTop: @param anchorBaselineToTop whether the baseline is anchored to the top or bottom of the group

      Returns

      parallel group

      See also

      • #createBaselineGroup

      • ParallelGroup

    • linkSize

      public void linkSize(Component[] components)

      Forces the set of components to have the same size. This can be used multiple times to force any number of components to share the same size.

      Linked Components are not be resizable.

      Parameters
      • components: Components to force to have same size.
      Throws
      • IllegalArgumentException: @throws IllegalArgumentException if components is null, or contains null.

    • linkSize

      public void linkSize(Component[] components, int axis)

      Forces the set of components to have the same size. This can be used multiple times to force any number of components to share the same size.

      Linked Components are not be resizable.

      Parameters

      • components: Components to force to have same size.

      • axis: @param axis Axis to bind size, one of HORIZONTAL, VERTICAL or HORIZONTAL | VERTICAL

      Throws

      • IllegalArgumentException: @throws IllegalArgumentException if components is null, or contains null.

      • IllegalArgumentException: @throws IllegalArgumentException if axis does not contain HORIZONTAL or VERTICAL

    • replace

      public void replace(Component existingComponent, Component newComponent)

      Removes an existing component replacing it with the specified component.

      Parameters

      • existingComponent: @param existingComponent the Component that should be removed and replaced with newComponent

      • newComponent: the Component to put in existingComponents place

      Throws
      • IllegalArgumentException: @throws IllegalArgumentException is either of the Components are null or if existingComponent is not being managed by this layout manager

    • getLayoutStyle

      public LayoutStyle getLayoutStyle()

      Returns the LayoutStyle instance to use

      Returns

      the LayoutStyle instance to use

    • setLayoutStyle

      public void setLayoutStyle(LayoutStyle layoutStyle)

      Sets the LayoutStyle this GroupLayout is to use. A value of null can be used to indicate the shared instance of LayoutStyle should be used.

      Parameters
      • layoutStyle: the LayoutStyle to use

    • removeLayoutComponent

      public void removeLayoutComponent(Component component)

      Notification that a Component has been removed from the parent container. You should not invoke this method directly, instead invoke removeComponent on the parent Container.

      Parameters
      • component: the component to be removed
      See also
      • Container#removeComponent
      Overrides:
      removeLayoutComponent in class Layout

    • getPreferredSize

      public Dimension getPreferredSize(Container parent)

      Returns the preferred size for the specified container.

      Parameters
      • parent: the container to return size for
      Throws

      • IllegalArgumentException: @throws IllegalArgumentException if parent is not the same Container that this was created with

      • IllegalStateException: @throws IllegalStateException if any of the components added to this layout are not in both a horizontal and vertical group

      See also
      • Container#getPreferredSize
      Specified by:
      getPreferredSize in class Layout

    • layoutContainer

      public void layoutContainer(Container parent)

      Lays out the specified container.

      Parameters
      • parent: the container to be laid out
      Throws
      • IllegalStateException: @throws IllegalStateException if any of the components added to this layout are not in both a horizontal and vertical group
      Specified by:
      layoutContainer in class Layout