Proper selection coloring in JFace Structured Viewers

bundles/org.eclipse.jface.text/src/org/eclipse/jface/internal/text/TableOwnerDrawSupport.java

@@ -25,6 +25,8 @@
 import org.eclipse.swt.widgets.Table;
 import org.eclipse.swt.widgets.TableItem;
 
+import org.eclipse.jface.viewers.ColumnViewerSelectionColorListener;
+
 
 /**
  * Adds owner draw support for tables.
@@ -83,7 +85,7 @@ public void handleEvent(Event event) {
 				measureItem(event);
 				break;
 			case SWT.EraseItem:
-				event.detail &= ~SWT.FOREGROUND;
+				event.detail&= ~SWT.FOREGROUND;
 				break;
 			case SWT.PaintItem:
 				performPaint(event);
@@ -147,7 +149,9 @@ private void performPaint(Event event) {
 		Color oldForeground= gc.getForeground();
 		Color oldBackground= gc.getBackground();
 
-		if (!isSelected) {
+		if (isSelected) {
+			ColumnViewerSelectionColorListener.drawSelection(event);
+		} else {
 			Color foreground= item.getForeground(index);
 			gc.setForeground(foreground);
 

bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ColumnViewerSelectionColorListener.java

@@ -0,0 +1,199 @@
+/*******************************************************************************
+ * Copyright (c) 2024 SAP SE.
+ *
+ * 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:
+ *     SAP SE - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.jface.viewers;
+
+import java.util.Arrays;
+
+import org.eclipse.jface.resource.ColorRegistry;
+import org.eclipse.jface.resource.JFaceResources;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.graphics.Color;
+import org.eclipse.swt.graphics.GC;
+import org.eclipse.swt.graphics.RGB;
+import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Event;
+import org.eclipse.swt.widgets.Listener;
+import org.eclipse.swt.widgets.Scrollable;
+
+/**
+ * EraseItem event listener that provides custom selection coloring for JFace
+ * viewers. This listener only activates when no custom owner draw label
+ * provider is registered, ensuring it doesn't conflict with existing custom
+ * drawing implementations.
+ * <p>
+ * The listener provides different colors for:
+ * <ul>
+ * <li>Selected items when the control has focus</li>
+ * <li>Selected items when the control doesn't have focus</li>
+ * </ul>
+ * </p>
+ *
+ * @see org.eclipse.jface.viewers.OwnerDrawLabelProvider
+ * @see org.eclipse.jface.viewers.StyledCellLabelProvider
+ * @see org.eclipse.jface.viewers.FocusCellOwnerDrawHighlighter
+ * @since 3.39
+ */
+public class ColumnViewerSelectionColorListener implements Listener {
+
+	private static final String LISTENER_KEY = "org.eclipse.jface.viewers.selection_color_listener"; //$NON-NLS-1$
+	private static final String OWNER_DRAW_LISTENER_KEY = "owner_draw_label_provider_listener"; //$NON-NLS-1$
+
+	private static final String COLOR_SELECTION_BG_FOCUS = "org.eclipse.jface.SELECTION_BACKGROUND_FOCUSED"; //$NON-NLS-1$
+	private static final String COLOR_SELECTION_FG_FOCUS = "org.eclipse.jface.SELECTION_FOREGROUND_FOCUSED"; //$NON-NLS-1$
+	private static final String COLOR_SELECTION_BG_NO_FOCUS = "org.eclipse.jface.SELECTION_BACKGROUND_NO_FOCUS"; //$NON-NLS-1$
+	private static final String COLOR_SELECTION_FG_NO_FOCUS = "org.eclipse.jface.SELECTION_FOREGROUND_NO_FOCUS"; //$NON-NLS-1$
+
+	/**
+	 * Registers the selection color listener on the given viewer.
+	 * <p>
+	 * This method is idempotent - calling it multiple times on the same viewer has
+	 * no additional effect.
+	 * </p>
+	 *
+	 * @param viewer the viewer to which the listener should be added
+	 */
+	public static void addListenerToViewer(StructuredViewer viewer) {
+		if ("gtk".equals(SWT.getPlatform())) { //$NON-NLS-1$
+			return; // Skip on Linux
+		}
+
+		Control control = viewer.getControl();
+		if (control.isDisposed() || isListenerRegistered(control)) {
+			return; // Already registered or disposed
+		}
+
+		ColumnViewerSelectionColorListener listener = new ColumnViewerSelectionColorListener();
+		control.setData(LISTENER_KEY, listener);
+		control.addListener(SWT.EraseItem, listener);
+	}
+
+	private static boolean isListenerRegistered(Control control) {
+		return control.getData(LISTENER_KEY) != null;
+	}
+
+	@Override
+	public void handleEvent(Event event) {
+		if ((event.detail & SWT.SELECTED) == 0) {
+			return; // Not selected
+		}
+
+		if (event.widget instanceof Control control && !control.isEnabled()) {
+			return; // Disabled control
+		}
+
+		if (hasAdditionalEraseItemListeners(event)) {
+			return; // Let other listeners handle selection
+		}
+
+		drawSelection(event);
+	}
+
+	/**
+	 * Checks if additional EraseItem listeners were registered after this listener
+	 * that are NOT the OwnerDrawListener. This allows user code to override the
+	 * selection coloring by adding their own EraseItem listener, while still
+	 * allowing StyledCellLabelProvider to work (which uses OwnerDrawListener but
+	 * doesn't draw selection).
+	 *
+	 * @param event the erase event
+	 * @return <code>true</code> if other custom listeners are present that should
+	 *         handle selection, <code>false</code> otherwise
+	 */
+	private boolean hasAdditionalEraseItemListeners(Event event) {
+		if (!(event.widget instanceof Control control)) {
+			return false;
+		}
+
+		Listener[] listeners = control.getListeners(SWT.EraseItem);
+		Object ownerDrawListener = control.getData(OWNER_DRAW_LISTENER_KEY);
+		return Arrays.stream(listeners).anyMatch(l -> l != this && l != ownerDrawListener);
+	}
+
+	/**
+	 * Draws custom selection coloring for the given event.
+	 * <p>
+	 * This method provides consistent selection rendering across different viewers
+	 * and owner draw implementations. It handles both focused and unfocused
+	 * selection states using themed colors from the ColorRegistry with appropriate
+	 * fallbacks.
+	 * </p>
+	 *
+	 * @param event the erase event containing the widget, GC, and coordinates
+	 * @since 3.32
+	 */
+	public static void drawSelection(Event event) {
+		if ("gtk".equals(SWT.getPlatform())) { //$NON-NLS-1$
+			return; // Skip on Linux
+		}
+
+		Control control = (Control) event.widget;
+		GC gc = event.gc;
+
+		Color backgroundColor;
+		Color foregroundColor;
+
+		if (control.isFocusControl()) {
+			backgroundColor = getSelectionColor(COLOR_SELECTION_BG_FOCUS, event.display);
+			foregroundColor = getSelectionColor(COLOR_SELECTION_FG_FOCUS, event.display);
+		} else {
+			backgroundColor = getSelectionColor(COLOR_SELECTION_BG_NO_FOCUS, event.display);
+			foregroundColor = getSelectionColor(COLOR_SELECTION_FG_NO_FOCUS, event.display);
+		}
+
+		gc.setBackground(backgroundColor);
+		gc.setForeground(foregroundColor);
+
+		int width = event.width;
+		if (event.widget instanceof Scrollable scrollable) {
+			width = scrollable.getClientArea().width;
+		}
+
+		gc.fillRectangle(0, event.y, width, event.height);
+
+		// Remove SELECTED and BACKGROUND flags to prevent native drawing from
+		// overwriting our custom colors
+		event.detail &= ~(SWT.SELECTED | SWT.BACKGROUND);
+	}
+
+	private static Color getSelectionColor(String key, org.eclipse.swt.graphics.Device device) {
+		ColorRegistry registry = JFaceResources.getColorRegistry();
+
+		if (registry.hasValueFor(key)) {
+			return registry.get(key);
+		}
+
+		RGB systemColor;
+		switch (key) {
+		case COLOR_SELECTION_BG_FOCUS:
+			systemColor = device.getSystemColor(SWT.COLOR_TITLE_BACKGROUND).getRGB();
+			break;
+		case COLOR_SELECTION_FG_FOCUS:
+			systemColor = device.getSystemColor(SWT.COLOR_WHITE).getRGB();
+			break;
+		case COLOR_SELECTION_BG_NO_FOCUS:
+			systemColor = device.getSystemColor(SWT.COLOR_TITLE_INACTIVE_BACKGROUND).getRGB();
+			break;
+		case COLOR_SELECTION_FG_NO_FOCUS:
+			systemColor = device.getSystemColor(SWT.COLOR_TITLE_INACTIVE_FOREGROUND).getRGB();
+			break;
+		default:
+			systemColor = device.getSystemColor(SWT.COLOR_LIST_SELECTION).getRGB();
+			break;
+		}
+
+		registry.put(key, systemColor);
+		return registry.get(key);
+	}
+
+}

bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java

@@ -1210,6 +1210,7 @@ public void widgetDefaultSelected(SelectionEvent e) {
 		});
 		handler.addPostSelectionListener(widgetSelectedAdapter(this::handlePostSelect));
 		handler.addOpenListener(StructuredViewer.this::handleOpen);
+		ColumnViewerSelectionColorListener.addListenerToViewer(this);
 	}
 
 	/**

bundles/org.eclipse.ui.themes/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Plugin.name
 Bundle-SymbolicName: org.eclipse.ui.themes;singleton:=true
-Bundle-Version: 1.2.2900.qualifier
+Bundle-Version: 1.2.3000.qualifier
 Bundle-Vendor: %Plugin.providerName
 Bundle-Localization: plugin
 Require-Bundle: org.eclipse.e4.ui.css.swt.theme

bundles/org.eclipse.ui.themes/css/dark/e4-dark_preferencestyle.css

@@ -76,4 +76,6 @@ IEclipsePreferences#org-eclipse-ui-workbench:org-eclipse-ui-themes { /* pseudo a
 		'org.eclipse.ui.editors.rangeIndicatorColor=27,118,153'
 		'org.eclipse.jface.REVISION_NEWEST_COLOR=75,44,3'
 		'org.eclipse.jface.REVISION_OLDEST_COLOR=154,113,61'
+		'org.eclipse.jface.SELECTION_FOREGROUND_NO_FOCUS=240,240,240'
+		'org.eclipse.jface.SELECTION_BACKGROUND_NO_FOCUS=95,95,95'
 }

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/themes/ColumnViewerSelectionColorFactory.java

@@ -0,0 +1,67 @@
+/*******************************************************************************
+ * Copyright (c) 2024 SAP SE.
+ *
+ * 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:
+ *     SAP SE - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.ui.internal.themes;
+
+import java.util.Hashtable;
+import org.eclipse.core.runtime.IConfigurationElement;
+import org.eclipse.core.runtime.IExecutableExtension;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.graphics.RGB;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.ui.themes.IColorFactory;
+
+/**
+ * Color factory for viewer selection colors that adapts to the OS/desktop
+ * theme. Provides default colors based on system colors for focused and
+ * unfocused selections.
+ * <p>
+ * The default colors are based on system title bar colors which automatically
+ * adapt to light/dark themes and high contrast modes. Themes can override these
+ * defaults to provide custom styling.
+ * </p>
+ *
+ * @since 3.39
+ */
+public class ColumnViewerSelectionColorFactory implements IColorFactory, IExecutableExtension {
+
+	private String color = null;
+
+	@Override
+	public RGB createColor() {
+		Display display = Display.getDefault();
+
+		if ("SELECTED_CELL_BACKGROUND".equals(color)) { //$NON-NLS-1$
+			return display.getSystemColor(SWT.COLOR_TITLE_BACKGROUND).getRGB();
+
+		} else if ("SELECTED_CELL_FOREGROUND".equals(color)) { //$NON-NLS-1$
+			return display.getSystemColor(SWT.COLOR_WHITE).getRGB();
+
+		} else if ("SELECTED_CELL_BACKGROUND_NO_FOCUS".equals(color)) { //$NON-NLS-1$
+			return display.getSystemColor(SWT.COLOR_TITLE_INACTIVE_BACKGROUND).getRGB();
+
+		} else if ("SELECTED_CELL_FOREGROUND_NO_FOCUS".equals(color)) { //$NON-NLS-1$
+			return display.getSystemColor(SWT.COLOR_TITLE_INACTIVE_FOREGROUND).getRGB();
+
+		} else {
+			return new RGB(0, 0, 0);
+		}
+	}
+
+	@Override
+	public void setInitializationData(IConfigurationElement config, String propertyName, Object data) {
+		if (data instanceof Hashtable table) {
+			this.color = (String) table.get("color"); //$NON-NLS-1$
+		}
+	}
+}

bundles/org.eclipse.ui/plugin.properties

@@ -371,6 +371,15 @@ Color.revisionNewestDesc=Background color for the newest revision shown in a tex
 Color.revisionOldest=Oldest revision background color
 Color.revisionOldestDesc=Background color for the oldest revision shown in a text editor's ruler. Together with the newest revision background color this defines a gradient used for all revision from newest to oldest.
 
+Color.viewerSelectionBackgroundFocused=Viewer selection background (focused)
+Color.viewerSelectionBackgroundFocusedDesc=Background color for selected items in viewers when the control has focus. Defaults to system highlight color. (No effect on Linux)
+Color.viewerSelectionForegroundFocused=Viewer selection foreground (focused)
+Color.viewerSelectionForegroundFocusedDesc=Foreground color for selected items in viewers when the control has focus. (No effect on Linux)
+Color.viewerSelectionBackgroundNoFocus=Viewer selection background (no focus)
+Color.viewerSelectionBackgroundNoFocusDesc=Background color for selected items in viewers when the control does not have focus. (No effect on Linux)
+Color.viewerSelectionForegroundNoFocus=Viewer selection foreground (no focus)
+Color.viewerSelectionForegroundNoFocusDesc=Foreground color for selected items in viewers when the control does not have focus. (No effect on Linux)
+
 Color.showKeysForeground=Keys foreground color
 Color.showKeysForegroundDesc=Color for foreground of the control to visualize pressed keys
 Color.showKeysBackground=Keys background color