TriStateCheckBox component added

flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/TriStateCheckBox.java

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2019 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.extras;
+
+import java.awt.event.ItemEvent;
+import javax.swing.JCheckBox;
+
+/**
+ * A tri-state check box.
+ *
+ * To display the third state, this component requires an LaF that supports painting
+ * the indeterminate state if client property {@code "JButton.selectedState"} has the
+ * value {@code "indeterminate"}.
+ *
+ * FlatLaf and Mac Aqua LaF support the third state.
+ *
+ * @author Karl Tauber
+ */
+public class TriStateCheckBox
+	extends JCheckBox
+{
+	public enum State { INDETERMINATE, SELECTED, UNSELECTED }
+
+	private State state;
+	private boolean thirdStateEnabled = true;
+
+	public TriStateCheckBox() {
+		this( null );
+	}
+
+	public TriStateCheckBox( String text ) {
+		this( text, State.INDETERMINATE );
+	}
+
+	public TriStateCheckBox( String text, State initialState ) {
+		super( text );
+
+		setModel( new ToggleButtonModel() {
+			@Override
+			public boolean isSelected() {
+				return state != State.UNSELECTED;
+			}
+
+			@Override
+			public void setSelected( boolean b ) {
+				switch( state ) {
+					case INDETERMINATE:			setState( State.SELECTED ); break;
+					case SELECTED:		setState( State.UNSELECTED ); break;
+					case UNSELECTED:	setState( thirdStateEnabled ? State.INDETERMINATE : State.SELECTED ); break;
+				}
+
+				fireStateChanged();
+				fireItemStateChanged( new ItemEvent( this, ItemEvent.ITEM_STATE_CHANGED, this,
+					isSelected() ? ItemEvent.SELECTED : ItemEvent.DESELECTED ) );
+			}
+		} );
+
+		setState( initialState );
+	}
+
+	public State getState() {
+		return state;
+	}
+
+	public void setState( State state ) {
+		if( this.state == state )
+			return;
+
+		State oldState = this.state;
+		this.state = state;
+
+		putClientProperty( "JButton.selectedState", state == State.INDETERMINATE ? "indeterminate" : null );
+
+		firePropertyChange( "state", oldState, state );
+		repaint();
+	}
+
+	public boolean isThirdStateEnabled() {
+		return thirdStateEnabled;
+	}
+
+	public void setThirdStateEnabled( boolean thirdStateEnabled ) {
+		this.thirdStateEnabled = thirdStateEnabled;
+
+		if( state == State.INDETERMINATE )
+			setState( State.UNSELECTED );
+	}
+
+	@Override
+	public void setSelected( boolean b ) {
+		setState( b ? State.SELECTED : State.UNSELECTED );
+	}
+}