add HorizontalSeparatorField

plugin/src/main/java/de/sebthom/eclipse/commons/prefs/fieldeditor/HorizontalSeparatorField.java

@@ -0,0 +1,77 @@
+/*
+ * SPDX-FileCopyrightText: © Sebastian Thomschke and contributors.
+ * SPDX-FileContributor: Sebastian Thomschke
+ * SPDX-License-Identifier: EPL-2.0
+ * SPDX-ArtifactOfProjectHomePage: https://github.com/sebthom/eclipse-commons
+ */
+package de.sebthom.eclipse.commons.prefs.fieldeditor;
+
+import org.eclipse.jdt.annotation.Nullable;
+import org.eclipse.jface.preference.FieldEditor;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Label;
+
+/**
+ * A pseudo field editor for displaying a horizontal separator.
+ *
+ * @author Sebastian Thomschke
+ */
+public class HorizontalSeparatorField extends FieldEditor {
+
+   private @Nullable Label separator;
+   private @Nullable GridData separatorLayoutData;
+
+   public HorizontalSeparatorField(final Composite parent) {
+      super("unused", "", parent);
+   }
+
+   @Override
+   protected void adjustForNumColumns(final int numColumns) {
+      final var labelLayoutData = separatorLayoutData;
+      if (labelLayoutData != null) {
+         labelLayoutData.horizontalSpan = numColumns;
+      } else {
+         separatorLayoutData = new GridData(GridData.FILL, GridData.CENTER, false, false, numColumns, 1);
+      }
+   }
+
+   @Override
+   protected void doFillIntoGrid(final Composite parent, final int numColumns) {
+      adjustForNumColumns(numColumns);
+      getLabelControl(parent).setLayoutData(separatorLayoutData);
+   }
+
+   @Override
+   protected void doLoad() {
+      // ignored
+   }
+
+   @Override
+   protected void doLoadDefault() {
+      // ignored
+   }
+
+   @Override
+   protected void doStore() {
+      // ignored
+   }
+
+   @Override
+   public Label getLabelControl(final Composite parent) {
+      var separator = this.separator;
+      if (separator == null || separator.isDisposed()) {
+         separator = this.separator = new Label(parent, SWT.SEPARATOR | SWT.HORIZONTAL);
+      } else {
+         checkParent(separator, parent);
+      }
+      return separator;
+   }
+
+   @Override
+   public int getNumberOfControls() {
+      return 1;
+   }
+
+}