Bug 575176: [UI-Workbench] Add StylingUtils

Change-Id: I492167a312bbf4ab3f1176fa9bf19609c6efa526

2 files changed, 124 insertions, 0 deletions

diff --git a/ecommons/org.eclipse.statet.ecommons.uimisc/META-INF/MANIFEST.MF b/ecommons/org.eclipse.statet.ecommons.uimisc/META-INF/MANIFEST.MF
index 6c803526..fb076ff4 100644
--- a/ecommons/org.eclipse.statet.ecommons.uimisc/META-INF/MANIFEST.MF
+++ b/ecommons/org.eclipse.statet.ecommons.uimisc/META-INF/MANIFEST.MF
@@ -13,6 +13,7 @@ Require-Bundle: org.eclipse.statet.ecommons.runtime.core;bundle-version="[4.5.0,
  org.eclipse.core.runtime;bundle-version="3.19.0",
  org.eclipse.e4.core.contexts;bundle-version="1.7.0";resolution:=optional,
  org.eclipse.ui,
+ org.eclipse.e4.ui.services,
  org.eclipse.jface.text;resolution:=optional,
  org.eclipse.core.databinding,
  org.eclipse.core.databinding.property,
@@ -38,6 +39,7 @@ Import-Package: com.ibm.icu.lang;version="67.1.0",
  org.eclipse.statet.ecommons.variables.core,
  org.eclipse.statet.jcommons.collections;version="4.5.0",
  org.eclipse.statet.jcommons.lang;version="4.5.0",
+ org.eclipse.e4.ui.css.swt.theme;resolution:=optional,
  org.eclipse.ui.dialogs;resolution:=optional,
  org.eclipse.ui.model;resolution:=optional,
  org.eclipse.ui.views.contentoutline;resolution:=optional,
diff --git a/ecommons/org.eclipse.statet.ecommons.uimisc/src/org/eclipse/statet/ecommons/ui/workbench/StylingUtils.java b/ecommons/org.eclipse.statet.ecommons.uimisc/src/org/eclipse/statet/ecommons/ui/workbench/StylingUtils.java
new file mode 100644
index 00000000..bc04d723
--- /dev/null
+++ b/ecommons/org.eclipse.statet.ecommons.uimisc/src/org/eclipse/statet/ecommons/ui/workbench/StylingUtils.java
@@ -0,0 +1,122 @@
+/*=============================================================================#
+ # Copyright (c) 2021 Stephan Wahlbrink and others.
+ # 
+ # This program and the accompanying materials are made available under the
+ # terms of the Eclipse Public License 2.0 which is available at
+ # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ # which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ # 
+ # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ # 
+ # Contributors:
+ #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
+ #=============================================================================*/
+
+package org.eclipse.statet.ecommons.ui.workbench;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+
+import org.eclipse.e4.ui.services.IStylingEngine;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.ui.PlatformUI;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+
+@NonNullByDefault
+public final class StylingUtils {
+	
+	
+	public static enum ThemeType {
+		
+		DARK,
+		LIGHT,
+		OTHER;
+		
+	}
+	
+	
+	/**
+	 * Key value for setting and getting the CSS ID of a widget.
+	 * 
+	 * @see org.eclipse.swt.widgets.Widget#getData(String)
+	 * @see org.eclipse.swt.widgets.Widget#setData(String, Object)
+	 */
+	/* org.eclipse.e4.ui.css.swt.CSSSWTConstants.CSS_ID_KEY */
+	public static final String WIDGET_CSS_ID_KEY= "org.eclipse.e4.ui.css.id"; //$NON-NLS-1$
+	
+	
+	private static final String SYSTEM_THEME_ID= "org.eclipse.e4.ui.css.theme.e4_system"; //$NON-NLS-1$
+	private static final String DEFAULT_THEME_ID= "org.eclipse.e4.ui.css.theme.e4_default"; //$NON-NLS-1$
+	private static final String DARK_THEME_ID= "org.eclipse.e4.ui.css.theme.e4_dark"; //$NON-NLS-1$
+	
+	private static final String NONE_THEME_ID= "none"; //$NON-NLS-1$
+	
+	
+	public static boolean isStylingSupported() {
+		return (PlatformUI.getWorkbench().getService(IStylingEngine.class) != null);
+	}
+	
+	public static IStylingEngine getStylingEngine() {
+		return nonNullAssert(PlatformUI.getWorkbench().getService(IStylingEngine.class));
+	}
+	
+	
+	@SuppressWarnings("restriction")
+	private static String getCurrentCssThemeId() {
+		try {
+			final var engine= PlatformUI.getWorkbench().getService(
+					org.eclipse.e4.ui.css.swt.theme.IThemeEngine.class );
+			if (engine != null) {
+				final var theme= engine.getActiveTheme();
+				if (theme != null) {
+					return theme.getId();
+				}
+			}
+		}
+		catch (final Exception e) {}
+		
+		return NONE_THEME_ID;
+	}
+	
+	public static ThemeType getCurrentThemeType(final Display display) {
+		final var themeId= getCurrentCssThemeId();
+		switch (themeId) {
+		case SYSTEM_THEME_ID:
+		case NONE_THEME_ID:
+			return (Display.isSystemDarkTheme()) ? ThemeType.DARK : ThemeType.LIGHT;
+		case DARK_THEME_ID:
+			return ThemeType.DARK;
+		case DEFAULT_THEME_ID:
+			return ThemeType.LIGHT;
+		default:
+			if (themeId.contains("dark")) { //$NON-NLS-1$
+				return ThemeType.DARK;
+			}
+			if (themeId.contains("light")) { //$NON-NLS-1$
+				return ThemeType.LIGHT;
+			}
+			return ThemeType.OTHER;
+		}
+	}
+	
+	public static boolean isCurrentThemeMatchingSystem(final Display display) {
+		final var themeId= getCurrentCssThemeId();
+		switch (themeId) {
+		case SYSTEM_THEME_ID:
+		case NONE_THEME_ID:
+			return true;
+		case DEFAULT_THEME_ID:
+			return !Display.isSystemDarkTheme();
+		default:
+			if (themeId.contains("dark")) { //$NON-NLS-1$
+				return Display.isSystemDarkTheme();
+			}
+			return false;
+		}
+	}
+	
+	
+	private StylingUtils() {}
+	
+}