--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwtx/draw2d/FocusTraverseManager.d	Sun Aug 03 00:52:14 2008 +0200
@@ -0,0 +1,195 @@
+/*******************************************************************************
+ * Copyright (c) 2000, 2005 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
+ *******************************************************************************/
+module dwtx.draw2d.FocusTraverseManager;
+
+import dwt.dwthelper.utils;
+import dwtx.dwtxhelper.Collection;
+import dwtx.draw2d.IFigure;
+
+/**
+ * This class is a helper to the {@link SWTEventDispatcher}. It handles the task of
+ * determining which Figure will gain focus upon a tab/shift-tab. It also keeps track of
+ * the Figure with current focus.
+ * <p>
+ * Note: When a Canvas with a {@link LightweightSystem} gains focus, it gives focus to the
+ * child Figure who had focus when this Canvas lost focus. If the canvas is gaining focus
+ * for the first time, focus is given to its first child Figure.
+ */
+public class FocusTraverseManager {
+
+IFigure currentFocusOwner;
+
+/**
+ * Default constructor.
+ */
+public this() { }
+
+private IFigure findDeepestRightmostChildOf(IFigure fig) {
+    while (fig.getChildren().size() !is 0) {
+        fig = cast(IFigure)fig.getChildren().get(fig.getChildren().size() - 1);
+    }
+    return fig;
+}
+
+/**
+ * Returns the IFigure that will receive focus upon a 'tab' traverse event.
+ *
+ * @param root the {@link LightweightSystem LightweightSystem's} root figure
+ * @param prevFocus the IFigure who currently owns focus
+ * @return the next focusable figure
+ */
+public IFigure getNextFocusableFigure(IFigure root, IFigure prevFocus) {
+    bool found = false;
+    IFigure nextFocus = prevFocus;
+
+    /*
+     * If no Figure currently has focus, apply focus to root's first focusable child.
+     */
+    if (prevFocus is null) {
+        if (root.getChildren().size() !is 0) {
+            nextFocus = (cast(IFigure)root.getChildren().get(0));
+            if (isFocusEligible(nextFocus))
+                return nextFocus;
+        } else
+            return null;
+    }
+
+    int siblingPos = nextFocus.getParent().getChildren().indexOf(cast(Object)nextFocus);
+    while (!found) {
+        IFigure parent = nextFocus.getParent();
+
+        /*
+         * Figure traversal is implemented using the pre-order left to right
+         * tree traversal algorithm.
+         *
+         * If the focused sibling has children, traverse to its leftmost child.
+         * If the focused sibling has no children, traverse to the sibling
+         * to its right.
+         * If there is no sibling to the right, go up the tree until a node
+         * with un-traversed siblings is found.
+         */
+        List siblings = parent.getChildren();
+
+        if (nextFocus.getChildren().size() !is 0) {
+            nextFocus = cast(IFigure)nextFocus.getChildren().get(0);
+            siblingPos = 0;
+            if (isFocusEligible(nextFocus))
+                found = true;
+        } else if (siblingPos < siblings.size() - 1) {
+            nextFocus = (cast(IFigure)(siblings.get(++siblingPos)));
+            if (isFocusEligible(nextFocus))
+                found = true;
+        } else {
+            bool untraversedSiblingFound = false;
+            while (!untraversedSiblingFound) {
+                IFigure p = nextFocus.getParent();
+                IFigure gp = p.getParent();
+
+                if (gp !is null) {
+                    int parentSiblingCount = gp.getChildren().size();
+                    int parentIndex = gp.getChildren().indexOf(cast(Object)p);
+                    if (parentIndex < parentSiblingCount - 1) {
+                        nextFocus = (cast(IFigure)p.getParent()
+                                .getChildren().get(parentIndex + 1));
+                        siblingPos = parentIndex + 1;
+                        untraversedSiblingFound = true;
+                        if (isFocusEligible(nextFocus))
+                            found = true;
+                    } else
+                        nextFocus = p;
+                } else {
+                    nextFocus = null;
+                    untraversedSiblingFound = true;
+                    found = true;
+                }
+            }
+        }
+    }
+    return nextFocus;
+}
+
+/**
+ * Returns the IFigure that will receive focus upon a 'shift-tab' traverse event.
+ *
+ * @param root The {@link LightweightSystem LightweightSystem's} root figure
+ * @param prevFocus The IFigure who currently owns focus
+ * @return the previous focusable figure
+ */
+public IFigure getPreviousFocusableFigure(IFigure root, IFigure prevFocus) {
+    if (prevFocus is null)
+        return null;
+
+    bool found = false;
+    IFigure nextFocus = prevFocus;
+    while (!found) {
+        IFigure parent = nextFocus.getParent();
+
+        /*
+         * At root, return null to indicate traversal
+         * is complete.
+         */
+        if (parent is null)
+            return null;
+
+        List siblings = parent.getChildren();
+        int siblingPos = siblings.indexOf(cast(Object)nextFocus);
+
+        /*
+         * Figure traversal is implemented using the post-order right to left
+         * tree traversal algorithm.
+         *
+         * Find the rightmost child.
+         * If this child is focusable, return it
+         * If not focusable, traverse to its sibling and repeat.
+         * If there is no sibling, traverse its parent.
+         */
+        if (siblingPos !is 0) {
+            IFigure child =
+                    findDeepestRightmostChildOf(cast(IFigure)siblings.get(siblingPos - 1));
+            if (isFocusEligible(child)) {
+                found = true;
+                nextFocus = child;
+            } else if ((cast(Object)child).opEquals(cast(Object)nextFocus)) {
+                if (isFocusEligible(nextFocus))
+                    found = true;
+            } else
+                nextFocus = child;
+        } else {
+            nextFocus = parent;
+                if (isFocusEligible(nextFocus))
+                    found = true;
+        }
+    }
+    return nextFocus;
+}
+
+/**
+ * @return the figure that currently has focus
+ */
+public IFigure getCurrentFocusOwner() {
+    return currentFocusOwner;
+}
+
+private bool isFocusEligible(IFigure fig) {
+    return (fig !is null && fig.isFocusTraversable() && fig.isShowing());
+}
+
+/**
+ * Sets the currently focused figure.
+ * @param fig the figure to get focus
+ */
+public void setCurrentFocusOwner(IFigure fig) {
+    currentFocusOwner = fig;
+}
+
+}