Add toggle group support for ToggleSwitch

base/src/main/java/atlantafx/base/controls/ToggleSwitch.java

@@ -35,6 +35,7 @@ import java.util.List;
 import javafx.beans.property.BooleanProperty;
 import javafx.beans.property.BooleanPropertyBase;
 import javafx.beans.property.ObjectProperty;
+import javafx.beans.property.ObjectPropertyBase;
 import javafx.beans.value.WritableValue;
 import javafx.css.CssMetaData;
 import javafx.css.PseudoClass;
@@ -44,11 +45,14 @@ import javafx.css.StyleableProperty;
 import javafx.css.converter.EnumConverter;
 import javafx.event.ActionEvent;
 import javafx.geometry.HorizontalDirection;
+import javafx.scene.AccessibleAttribute;
 import javafx.scene.control.Labeled;
 import javafx.scene.control.Skin;
+import javafx.scene.control.Toggle;
+import javafx.scene.control.ToggleGroup;
 
 @SuppressWarnings("unused")
-public class ToggleSwitch extends Labeled {
+public class ToggleSwitch extends Labeled implements Toggle {
 
     protected static final String DEFAULT_STYLE_CLASS = "toggle-switch";
     protected static final PseudoClass PSEUDO_CLASS_SELECTED = PseudoClass.getPseudoClass("selected");
@@ -96,6 +100,39 @@ public class ToggleSwitch extends Labeled {
         if (selected == null) {
             selected = new BooleanPropertyBase() {
 
+                @Override
+                protected void invalidated() {
+                    final boolean selected = get();
+                    final ToggleGroup tg = getToggleGroup();
+                    pseudoClassStateChanged(PSEUDO_CLASS_SELECTED, selected);
+                    notifyAccessibleAttributeChanged(AccessibleAttribute.SELECTED);
+
+                    if (tg != null) {
+                        if (selected) {
+                            tg.selectToggle(ToggleSwitch.this);
+                        } else if (tg.getSelectedToggle() == ToggleSwitch.this) {
+                            // This code was copied from ToggleButton, and originally
+                            // it should use the following method, which is like almost
+                            // everything in JavaFX is private. Probably it fixes some
+                            // internal toggle group state.
+                            // tg.clearSelectedToggle();
+
+                            // This is kind of an equivalent code even though
+                            // "!tg.getSelectedToggle().isSelected()"
+                            // looks like absurd and should always return false.
+                            if (!tg.getSelectedToggle().isSelected()) {
+                                for (Toggle toggle: tg.getToggles()) {
+                                    if (toggle.isSelected()) {
+                                        return;
+                                    }
+                                }
+                            }
+
+                            tg.selectToggle(null);
+                        }
+                    }
+                }
+
                 @Override
                 public Object getBean() {
                     return ToggleSwitch.this;
@@ -105,18 +142,65 @@ public class ToggleSwitch extends Labeled {
                 public String getName() {
                     return "selected";
                 }
-
-                @Override
-                protected void invalidated() {
-                    final boolean v = get();
-                    pseudoClassStateChanged(PSEUDO_CLASS_SELECTED, v);
-                }
             };
         }
 
         return selected;
     }
 
+    /**
+     * The {@link ToggleGroup} to which this {@code ToggleSwitch} belongs.
+     * A {@code ToggleSwitch} can only be in one group at any one time. If the
+     * group is changed, then the button is removed from the old group prior to
+     * being added to the new group.
+     */
+    private ObjectProperty<ToggleGroup> toggleGroup;
+
+    @Override
+    public final void setToggleGroup(ToggleGroup value) {
+        toggleGroupProperty().set(value);
+    }
+
+    @Override
+    public final ToggleGroup getToggleGroup() {
+        return toggleGroup == null ? null : toggleGroup.get();
+    }
+
+    @Override
+    public final ObjectProperty<ToggleGroup> toggleGroupProperty() {
+        if (toggleGroup == null) {
+            toggleGroup = new ObjectPropertyBase<>() {
+                private ToggleGroup old;
+
+                @Override
+                protected void invalidated() {
+                    final ToggleGroup tg = get();
+                    if (tg != null && !tg.getToggles().contains(ToggleSwitch.this)) {
+                        if (old != null) {
+                            old.getToggles().remove(ToggleSwitch.this);
+                        }
+                        tg.getToggles().add(ToggleSwitch.this);
+                    } else if (tg == null) {
+                        old.getToggles().remove(ToggleSwitch.this);
+                    }
+
+                    old = tg;
+                }
+
+                @Override
+                public Object getBean() {
+                    return ToggleSwitch.this;
+                }
+
+                @Override
+                public String getName() {
+                    return "toggleGroup";
+                }
+            };
+        }
+        return toggleGroup;
+    }
+
     // ~
 
     private ObjectProperty<HorizontalDirection> labelPosition;

sampler/src/main/java/atlantafx/sampler/page/components/ToggleSwitchPage.java

@@ -11,6 +11,9 @@ import atlantafx.sampler.page.Snippet;
 import java.net.URI;
 import javafx.geometry.HorizontalDirection;
 import javafx.geometry.Pos;
+import javafx.scene.control.Label;
+import javafx.scene.control.ToggleGroup;
+import javafx.scene.layout.GridPane;
 import javafx.scene.layout.HBox;
 
 public final class ToggleSwitchPage extends OutlinePage {
@@ -38,6 +41,7 @@ public final class ToggleSwitchPage extends OutlinePage {
         );
         addSection("Usage", usageExample());
         addSection("Color", colorExample());
+        addSection("Toggle Group", toggleGroupExample());
     }
 
     private ExampleBox usageExample() {
@@ -97,4 +101,34 @@ public final class ToggleSwitchPage extends OutlinePage {
 
         return new ExampleBox(box, new Snippet(getClass(), 2), description);
     }
+
+    private ExampleBox toggleGroupExample() {
+        //snippet_3:start
+        var group = new ToggleGroup();
+
+        var toggle1 = new ToggleSwitch();
+        toggle1.setToggleGroup(group);
+        toggle1.setSelected(true);
+
+        var toggle2 = new ToggleSwitch();
+        toggle2.setToggleGroup(group);
+
+        var toggle3 = new ToggleSwitch();
+        toggle3.setToggleGroup(group);
+        //snippet_3:end
+
+        var grid = new GridPane();
+        grid.setHgap(HGAP_20);
+        grid.setVgap(VGAP_10);
+        grid.addRow(0, new Label("Option 1"), toggle1);
+        grid.addRow(1, new Label("Option 2"), toggle2);
+        grid.addRow(2, new Label("Option 3"), toggle3);
+
+        var description = BBCodeParser.createFormattedText("""
+            Toggles can optionally be combined into a group where only one switch \
+            at a time can be selected."""
+        );
+
+        return new ExampleBox(grid, new Snippet(getClass(), 3), description);
+    }
 }