1 files changed, 119 insertions, 0 deletions
diff --git a/plugins/views/properties/org.eclipse.papyrus.views.properties.toolsmiths/src/org/eclipse/papyrus/views/properties/toolsmiths/editor/actions/AbstractToggleHandler.java b/plugins/views/properties/org.eclipse.papyrus.views.properties.toolsmiths/src/org/eclipse/papyrus/views/properties/toolsmiths/editor/actions/AbstractToggleHandler.java
new file mode 100644
index 00000000000..624862c58bb
--- /dev/null
+++ b/plugins/views/properties/org.eclipse.papyrus.views.properties.toolsmiths/src/org/eclipse/papyrus/views/properties/toolsmiths/editor/actions/AbstractToggleHandler.java
@@ -0,0 +1,119 @@
+/*****************************************************************************
+ * Copyright (c) 2021 CEA LIST, Christian W. Damus, and others.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ * Christian W. Damus - Initial API and implementation
+ *
+ *****************************************************************************/
+package org.eclipse.papyrus.views.properties.toolsmiths.editor.actions;
+
+import org.eclipse.core.commands.AbstractHandler;
+import org.eclipse.core.commands.Command;
+import org.eclipse.core.commands.ExecutionEvent;
+import org.eclipse.core.commands.ExecutionException;
+import org.eclipse.core.commands.State;
+import org.eclipse.ui.ISources;
+import org.eclipse.ui.IWorkbenchPage;
+import org.eclipse.ui.IWorkbenchWindow;
+import org.eclipse.ui.commands.ICommandService;
+import org.eclipse.ui.handlers.HandlerUtil;
+
+/**
+ * A simple framework for toggle actions.
+ */
+public abstract class AbstractToggleHandler extends AbstractHandler {
+
+	private static final String STATE_ID = "org.eclipse.ui.commands.toggleState"; //$NON-NLS-1$
+
+	private final String commandID;
+
+	private State state;
+
+	protected AbstractToggleHandler(String commandID) {
+		super();
+
+		this.commandID = commandID;
+	}
+
+	@Override
+	public Object execute(ExecutionEvent event) throws ExecutionException {
+		IWorkbenchPage activePage = HandlerUtil.getActiveWorkbenchWindowChecked(event).getActivePage();
+		if (activePage == null || state == null) {
+			return null;
+		}
+
+		boolean current = (Boolean) state.getValue();
+		doToggle(activePage, !current);
+
+		return null;
+	}
+
+	@Override
+	public void setEnabled(Object evaluationContext) {
+		super.setEnabled(evaluationContext);
+
+		IWorkbenchWindow activeWindow = (IWorkbenchWindow) HandlerUtil.getVariable(evaluationContext, ISources.ACTIVE_WORKBENCH_WINDOW_NAME);
+		IWorkbenchPage activePage = activeWindow == null ? null : activeWindow.getActivePage();
+		if (activePage == null) {
+			return;
+		}
+
+		ICommandService commandService = activeWindow.getService(ICommandService.class);
+		Command command = commandService.getCommand(commandID);
+
+		if (this.state == null) {
+			State state = (command == null) ? null : command.getState(STATE_ID);
+			if (state == null) {
+				return;
+			}
+
+			// Initialize from the persistent state
+			this.state = state;
+			boolean fromState = (Boolean) state.getValue();
+			boolean initial = initializeFromState(activePage, fromState);
+			state.setValue(initial);
+		} else {
+			this.state.setValue(updateState(activePage));
+		}
+	}
+
+	/**
+	 * Handle the toggling of the action state.
+	 *
+	 * @param page
+	 *            the current workbench page in which to apply the effect of toggling
+	 * @param on
+	 *            {@code true} if the toggle is on, {@code false} if it is off
+	 */
+	protected abstract void doToggle(IWorkbenchPage page, boolean on);
+
+	/**
+	 * Compute an update to the state based on the current reality of the workbench.
+	 *
+	 * @param page
+	 *            the current workbench page from which to compute the updated state
+	 * @return the updated state
+	 */
+	protected abstract boolean updateState(IWorkbenchPage page);
+
+	/**
+	 * Reconcile the initial action state in the workbench with the persistent state value.
+	 *
+	 * @param page
+	 *            the current workbench page from in which reconcile the initial state
+	 * @param on
+	 *            {@code true} if the toggle is on, {@code false} if it is off
+	 * @return the value to update in the initial state. If this is the same as {@code on}, then the state will not be updated
+	 */
+	protected boolean initializeFromState(IWorkbenchPage page, boolean on) {
+		return on;
+	}
+
+}