A step down the road toward interface elements that look after themselves.

git-svn-id: https://samskivert.googlecode.com/svn/trunk@875 6335cc39-0255-0410-8fd6-9bcaacd3b74c
2002-10-23 02:06:14 +00:00
parent 229591d213
commit 8dd1b4c4bb
1 changed files with 80 additions and 0 deletions
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+//
+// $Id: EnablingAdapter.java,v 1.1 2002/10/23 02:06:14 mdb Exp $
+
+package com.samskivert.swing;
+
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
+
+import javax.swing.JComponent;
+
+import com.samskivert.Log;
+
+/**
+ * Used to enable or disable a source component based on some
+ * asynchronously changing state.
+ */
+public class EnablingAdapter
+{
+    /**
+     * Creates and returns an enabler that listens for changes in the
+     * specified property (which must be a {@link Boolean} valued
+     * property) and updates the target's enabled state accordingly.
+     */
+    public static PropertyChangeListener getPropChangeEnabler (
+        String property, JComponent target, boolean invert)
+    {
+        return new PropertyChangeEnabler(property, target, invert);
+    }
+
+    /**
+     * Creates an enabling adapter with the specified target component.
+     *
+     * @param invert if true, the target component's enabled state is set
+     * to the inverse of the monitored state.
+     */
+    protected EnablingAdapter (JComponent target, boolean invert)
+    {
+        _target = target;
+        _invert = invert;
+    }
+
+    /**
+     * Called by the appropriate derived adapter to adjust the target's
+     * enabled state.
+     */
+    protected void stateChanged (boolean newState)
+    {
+        _target.setEnabled(_invert ? !newState : newState);
+    }
+
+    /** Used by {@link #getPropChangeEnabler}. */
+    protected static class PropertyChangeEnabler extends EnablingAdapter
+        implements PropertyChangeListener
+    {
+        public PropertyChangeEnabler (
+            String property, JComponent target, boolean invert)
+        {
+            super(target, invert);
+            _property = property;
+        }
+
+        public void propertyChange (PropertyChangeEvent evt)
+        {
+            if (evt.getPropertyName().equals(_property)) {
+                Object value = evt.getNewValue();
+                if (value instanceof Boolean) {
+                    stateChanged(((Boolean)value).booleanValue());
+                } else {
+                    Log.warning("PropertyChangeEnabler connected to " +
+                                "non-Boolean property [got=" + value + "].");
+                }
+            }
+        }
+
+        protected String _property;
+    }
+
+    protected JComponent _target;
+    protected boolean _invert;
+}