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package javax.swing;

import java.util.Comparator;
import java.util.LinkedList;
import java.util.ListIterator;
import java.awt.Component;
import java.awt.ComponentOrientation;
import java.awt.Window;


Comparator which attempts to sort Components based on their size and position. Code adapted from original javax.swing.DefaultFocusManager implementation.
Author:David Mendenhall
/** * Comparator which attempts to sort Components based on their size and * position. Code adapted from original javax.swing.DefaultFocusManager * implementation. * * @author David Mendenhall */
final class LayoutComparator implements Comparator<Component>, java.io.Serializable { private static final int ROW_TOLERANCE = 10; private boolean horizontal = true; private boolean leftToRight = true; void setComponentOrientation(ComponentOrientation orientation) { horizontal = orientation.isHorizontal(); leftToRight = orientation.isLeftToRight(); } public int compare(Component a, Component b) { if (a == b) { return 0; } // Row/Column algorithm only applies to siblings. If 'a' and 'b' // aren't siblings, then we need to find their most inferior // ancestors which share a parent. Compute the ancestory lists for // each Component and then search from the Window down until the // hierarchy branches. if (a.getParent() != b.getParent()) { LinkedList<Component> aAncestory = new LinkedList<Component>(); for(; a != null; a = a.getParent()) { aAncestory.add(a); if (a instanceof Window) { break; } } if (a == null) { // 'a' is not part of a Window hierarchy. Can't cope. throw new ClassCastException(); } LinkedList<Component> bAncestory = new LinkedList<Component>(); for(; b != null; b = b.getParent()) { bAncestory.add(b); if (b instanceof Window) { break; } } if (b == null) { // 'b' is not part of a Window hierarchy. Can't cope. throw new ClassCastException(); } for (ListIterator<Component> aIter = aAncestory.listIterator(aAncestory.size()), bIter = bAncestory.listIterator(bAncestory.size()); ;) { if (aIter.hasPrevious()) { a = aIter.previous(); } else { // a is an ancestor of b return -1; } if (bIter.hasPrevious()) { b = bIter.previous(); } else { // b is an ancestor of a return 1; } if (a != b) { break; } } } int ax = a.getX(), ay = a.getY(), bx = b.getX(), by = b.getY(); int zOrder = a.getParent().getComponentZOrder(a) - b.getParent().getComponentZOrder(b); if (horizontal) { if (leftToRight) { // LT - Western Europe (optional for Japanese, Chinese, Korean) if (Math.abs(ay - by) < ROW_TOLERANCE) { return (ax < bx) ? -1 : ((ax > bx) ? 1 : zOrder); } else { return (ay < by) ? -1 : 1; } } else { // !leftToRight // RT - Middle East (Arabic, Hebrew) if (Math.abs(ay - by) < ROW_TOLERANCE) { return (ax > bx) ? -1 : ((ax < bx) ? 1 : zOrder); } else { return (ay < by) ? -1 : 1; } } } else { // !horizontal if (leftToRight) { // TL - Mongolian if (Math.abs(ax - bx) < ROW_TOLERANCE) { return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder); } else { return (ax < bx) ? -1 : 1; } } else { // !leftToRight // TR - Japanese, Chinese, Korean if (Math.abs(ax - bx) < ROW_TOLERANCE) { return (ay < by) ? -1 : ((ay > by) ? 1 : zOrder); } else { return (ax > bx) ? -1 : 1; } } } } }