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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2007-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.swing
import javax.swing.JComponent
import scala.collection.mutable.Map
/** <p>
* A container that associates layout constraints of member type
* <code>Constraints</code> with its children. See <code>GridBagPanel</code>
* for an example container with custom constraints.
* </p>
*
* @note [Java Swing] In scala.swing, panels and layout managers are
* combined into subclasses of this base class. This approach allows for typed
* component constraints.
*/
trait LayoutContainer extends Container.Wrapper {
/**
* The type of component constraints for this container.
*/
type Constraints <: AnyRef
/**
* Obtains the constraints for the given component from the underlying
* Swing layout manager.
*/
protected def constraintsFor(c: Component): Constraints
/**
* Checks whether the given constraints are valid. Additionally returns
* an error string that is only fetched if the constraints aren't valid.
*/
protected def areValid(c: Constraints): (Boolean, String)
/**
* Adds a component with the given constraints to the underlying layout
* manager and the component peer.
*/
protected def add(comp: Component, c: Constraints)
/**
* A map of components to the associated layout constraints.
* Any element in this map is automatically added to the contents of this
* panel. Therefore, specifying the layout of a component via
*
* layout(myComponent) = myConstraints
*
* also ensures that myComponent is properly add to this container.
*/
def layout: Map[Component, Constraints] = new Map[Component, Constraints] {
def -= (c: Component): this.type = { _contents -= c; this }
def += (cl: (Component, Constraints)): this.type = { update(cl._1, cl._2); this }
override def update (c: Component, l: Constraints) {
val (v, msg) = areValid(l)
if (!v) throw new IllegalArgumentException(msg)
add(c, l)
this
}
def get(c: Component) = Swing.toOption(constraintsFor(c))
override def size = peer.getComponentCount
def iterator: Iterator[(Component, Constraints)] =
Iterator.range(0,size).map { c =>
val comp = UIElement.cachedWrapper[Component](peer.getComponent(c).asInstanceOf[JComponent])
(comp, constraintsFor(comp))
}
}
}
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