Indicates whether gaps between components and the container borders are automatically created.
Sets whether gaps between components and the container borders are automatically created.
Indicates whether gaps between components are automatically created.
Sets whether gaps between components are automatically created.
The component will not take up any space when it's invisible (default).
Indicates whether the visibility of components is considered for the layout.
Indicates whether the visibility of components is considered for the layout.
If set to false, invisible components still take up space.
Defaults to true.
Sets whether the visibility of components should be considered for the layout.
Sets whether the visibility of components should be considered for the
layout. If set to false, invisible components still take up
space. Defaults to true.
The component will still take up its space even when invisible.
This panel's underlying layout manager is a GroupLayout instance.
Returns the layout style used.
Assigns a layout style to use.
Links the sizes of several components horizontally.
Links the sizes of several components horizontally.
the components to link
Links the sizes (horizontal and vertical) of several components.
Links the sizes (horizontal and vertical) of several components.
the components to link
Links the sizes of several components vertically.
Links the sizes of several components vertically.
the components to link
Replaces one component with another.
Replaces one component with another. Useful for dynamic layouts.
the component to be replaced
the component replacing the existing one
This method is needed for implicit resolution in Scala 2.
This method is needed for implicit resolution in Scala 2.10 due to some bug (?). It is not needed any more for Scala 2.11
This method is needed for implicit resolution in Scala 2.
This method is needed for implicit resolution in Scala 2.10 due to some bug (?). It is not needed any more for Scala 2.11
A panel that uses javax.swing.GroupLayout to visually arrange its components.
Note: This is a slightly adapted variant of the original
GroupPanelclass by Andreas Flier and which was part of the ScalaSwingContrib project. We thought it was a bit over-engineered, and also some naming was problematic (theHorizontalLayout is ...) and involving reflection-based structural types.The key point to understanding this layout manager is that it separates horizontal and vertical layout. Thus, every component appears twice: once in the horizontal and once in the vertical layout. Consult the Java API documentation for
GroupLayoutand Sun's Java tutorials for a comprehensive explanation.The main advantage of using this panel instead of manually tinkering with the layout is that this panel provides a concise, declarative syntax for laying out its components. This approach should make most use cases easier. In some special cases, e.g. when re-creating layouts on-the-fly, it might be preferable to use a more imperative style, for which direct access to the underlying layout manager is provided.
In contrast to the underlying swing layout, this panel activates the automatic creation of gaps between components by default, since this panel is intended for coding UIs "by hand", not so much for visual UI builder tools. Many features of the underlying layout are aimed at those, tough. Most of them are available through this panel for completeness' sake but it is anticipated that coders won't need to use them very much.
Code examples
This section contains a few simple examples to showcase the basic functionality of
GroupPanels. For all examples, it is assumed that everything from the packagescala.swingis imported and the code is placed inside a scala.swing.SimpleSwingApplication like this:Simple panel with 2 components
In the first example, there's a label and a text field, which appear in a horizontal sequence but share the same vertical space.
It can be observed that the resize behaviour of the text field is rather strange. To get better behaviour, the components' vertical sizes can be linked together.
Alternatively, it would have been possible to disallow the resizing of the vertical, parallel group. To achieve this, the vertical layout line should be written this way:
Since text fields aren't resizable when used with baseline alignment (more about that further down), the following code also prevents (vertical) resizing:
Size and alignment
Components can be added with custom size constraints (minimum, preferred, maximum size). The next example showcases that. The text field appears with a preferred height of 100 pixels and when the component is resized, it can be reduced to its minimum height of 50 pixels and enlarged to its maximum height of 200 pixels.
The
Sizeobject holds some useful constants:Default,PreferredandInfinite, that can be used for any of the minimum, preferred and maximum arguments.Instead of using these hints with
Size.apply, one can also use the provided convenience methodsSize.fixedandSize.fill.Because the default alignment in a parallel group is
Leading, both components are "glued" to the top of the container (panel). To align the label's text with the text inside the text field, an explicit alignment can be specified in a preceding argument list, like this:This example also shows a potential problem of baseline alignment: some components stop being resizable. More specifically, the javadoc for
GroupLayout.ParallelGroupstates:CONSTANT_ASCENTorCONSTANT_DESCENT.OTHERorCENTER_OFFSETare not resizable.Since a text field's resizing behaviour is
CENTER_OFFSET, it is not resizable when used with baseline alignment.Gaps
The
GroupPanelturns on automatic creation of gaps between components and along the container edges. To see the difference, try turning this feature off manually by inserting the following lines:With both types of gaps missing, the components are clamped together and to the container edges, which does not look very pleasing. Gaps can be added manually, too. The following example does this in order to get a result that looks similar to the version with automatically created gaps, albeit in a much more verbose manner.
Rigid gaps with custom size or completely manual gaps (specifying minimum, preferred and maximum size) between components are created with the
Gapobject:In a parallel group, such a gap can be used to specify a minimum amount of space taken by the group.
In addition to rigid gaps in the previous example, it is also possible to specify gaps that resize. This could be done by specifying a maximum size of
Infinite. However, for the most commonly used type of these, there is a bit of syntax sugar available with theSpringandContainerSpringmethods.These create gaps that minimally are as wide as a
Gap.Preferredwould be - it is possible to specify whether theRelatedorUnrelateddistance should be used - but can be resized to an arbitrary size.bc.. horizontal = Seq( Gap.Container(), label, Gap.Spring(Unrelated), textField, Gap.ContainerSpring() )The preferred size can also be specified more closely (
Size.DefaultorSize.Infiniteaka "as large as possible"):bc.. horizontal = Seq( Gap.Container(), label, Gap.Spring(Unrelated, Size.Infinite), textField, Gap.ContainerSpring(Size.Infinite) )Please note that
Gap.Preferred,Spring,Gap.ContainerandSpring.Containermay only be used inside a sequential group.A dialog with several components
As a last, more sophisticated example, here's the
GroupPanelversion of the "Find" dialog presented as example forGroupLayoutin the Java tutorials by Sun:Mapping component sequences
Often you will want to build panels from a sequence of components and arrange them in a grid. The
Seq.applyandPar.applymethods take a sequence ofGroupPanel.Elementinstances, and therefore you may have to explicitly convert them, as the implicit conversion does not kick in for collections. There are two possibilities, as demonstrated in the last example:As can be seen, the
SeqandParclasses can be instantiated and then populated through calls to thecontentsmember.javax.swing.GroupLayout