src/Pure/GUI/tree_view.scala

clarified default: avoid copies;

/*  Title:      Pure/GUI/tree_view.scala
    Author:     Makarius

Tree view with sensible defaults.
*/

package isabelle

import javax.swing.JTree
import javax.swing.tree.{MutableTreeNode, DefaultMutableTreeNode, DefaultTreeModel,
  TreeSelectionModel, TreeCellRenderer, DefaultTreeCellRenderer}


object Tree_View {
  type Node = DefaultMutableTreeNode

  object Node {
    def apply(obj: AnyRef = null): Node =
      if (obj == null) new DefaultMutableTreeNode else new DefaultMutableTreeNode(obj)

    def unapply(tree_node: MutableTreeNode): Option[AnyRef] =
      tree_node match {
        case node: Node => Some(node.getUserObject)
        case _ => None
      }
  }

  def render_tree_cell(renderer: DefaultTreeCellRenderer): Unit = {
    renderer.setIcon(null)
  }
}

class Tree_View(
  val root: Tree_View.Node = Tree_View.Node(),
  single_selection_mode: Boolean = false
) extends JTree(root) {
  def get_selection[A](which: PartialFunction[AnyRef, A]): Option[A] =
    getLastSelectedPathComponent match {
      case Tree_View.Node(obj) if obj != null && which.isDefinedAt(obj) => Some(which(obj))
      case _ => None
    }

  def init_model(body: => Unit): Unit = {
    clearSelection()
    root.removeAllChildren()
    body
    expandRow(0)
    reload_model()
  }

  def reload_model(): Unit =
    getModel match {
      case model: DefaultTreeModel => model.reload(root)
      case _ =>
    }


  /* cell renderer */

  def render_tree_cell(renderer: DefaultTreeCellRenderer): Unit =
    Tree_View.render_tree_cell(renderer)

  private val tree_cell_renderer: TreeCellRenderer = new DefaultTreeCellRenderer {
    override def getTreeCellRendererComponent(
      tree: JTree,
      value: AnyRef,
      selected: Boolean,
      expanded: Boolean,
      leaf: Boolean,
      row: Int,
      hasFocus: Boolean
    ): java.awt.Component = {
      super.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus)
      render_tree_cell(this)
      this
    }
  }


  /* init */

  setCellRenderer(tree_cell_renderer)

  setRowHeight(0)

  if (single_selection_mode) {
    getSelectionModel.setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION)
  }

  // follow jEdit
  if (!GUI.is_macos_laf) {
    putClientProperty("JTree.lineStyle", "Angled")
  }
}