1 /*
   2  * Copyright (c) 2009, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javafx.scene.layout;
  27 
  28 import java.util.Iterator;
  29 
  30 import javafx.scene.Node;
  31 import javafx.scene.Parent;
  32 
  33 import com.sun.javafx.util.WeakReferenceQueue;
  34 
  35 /**
  36  * The base class for defining node-specific layout constraints.  Region
  37  * classes may create extensions of this class if they need to define their own
  38  * set of layout constraints.
  39  *
  40  * @since JavaFX 2.0
  41  */
  42 public abstract class ConstraintsBase {
  43 
  44     /**
  45      * If set as max value indicates that the pref value should be used as the max.
  46      * This allows an application to constrain a resizable node's size, which normally
  47      * has an unlimited max value, to its preferred size.
  48      */
  49     public static final double CONSTRAIN_TO_PREF = Double.NEGATIVE_INFINITY;
  50 
  51      WeakReferenceQueue impl_nodes = new WeakReferenceQueue();
  52      
  53      ConstraintsBase() {
  54      }
  55 
  56      void add(Parent node) {
  57          impl_nodes.add(node);
  58      }
  59 
  60     void remove(Parent node) {
  61         impl_nodes.remove(node);
  62     }
  63 
  64      /**
  65       * Calls requestLayout on layout parent associated with this constraint object.
  66       */
  67      protected void requestLayout() {
  68         Iterator<Parent> nodeIter = impl_nodes.iterator();
  69 
  70         while (nodeIter.hasNext()) {
  71             nodeIter.next().requestLayout();
  72         }
  73     }
  74 }