Bug 575176: [R-Help] Improve rendering for dark theme

Change-Id: I52574dab612bd310663d7833080054adc75a1097

4 files changed, 332 insertions, 168 deletions

diff --git a/r/org.eclipse.statet.r.ui/META-INF/MANIFEST.MF b/r/org.eclipse.statet.r.ui/META-INF/MANIFEST.MF
index 0483cb38..83fc3432 100644
--- a/r/org.eclipse.statet.r.ui/META-INF/MANIFEST.MF
+++ b/r/org.eclipse.statet.r.ui/META-INF/MANIFEST.MF
@@ -18,6 +18,7 @@ Require-Bundle: org.eclipse.statet.ecommons.runtime.core;bundle-version="[4.5.0,
  org.eclipse.core.databinding.beans,
  org.eclipse.jface.databinding,
  org.eclipse.ui.forms,
+ org.eclipse.e4.ui.services,
  org.eclipse.ui.views,
  org.eclipse.ui.ide,
  org.eclipse.compare,
diff --git a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java
index b946c37d..6e8ade27 100644
--- a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java
+++ b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java
@@ -304,8 +304,8 @@ class RHelpInfoControl extends AbstractInformationControl implements IInformatio
 			public void keyReleased(final KeyEvent e) {}
 		});
 		
-		setBackgroundColor(RHelpUIServlet.getDocBackgroundColor());
-		setForegroundColor(RHelpUIServlet.getDocForegroundColor());
+		setBackgroundColor(RHelpWorkbenchStyle.getDocBackgroundColor());
+		setForegroundColor(RHelpWorkbenchStyle.getDocForegroundColor());
 		
 		if ((this.mode & MODE_FOCUS) != 0) {
 			initActions(this.handlerCollection);
diff --git a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpUIServlet.java b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpUIServlet.java
index 72259341..a15649e1 100644
--- a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpUIServlet.java
+++ b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpUIServlet.java
@@ -14,7 +14,7 @@
 
 package org.eclipse.statet.internal.r.ui.rhelp;
 
-import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+import static org.eclipse.statet.internal.r.ui.rhelp.RHelpWorkbenchStyle.appendCssColor;
 
 import java.io.PrintWriter;
 import java.nio.file.Path;
@@ -30,22 +30,15 @@ import org.eclipse.core.filesystem.EFS;
 import org.eclipse.core.filesystem.IFileStore;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.preference.JFacePreferences;
-import org.eclipse.jface.preference.PreferenceConverter;
-import org.eclipse.jface.resource.FontDescriptor;
 import org.eclipse.jface.resource.JFaceResources;
 import org.eclipse.jface.text.rules.IToken;
 import org.eclipse.jface.util.IPropertyChangeListener;
 import org.eclipse.jface.util.PropertyChangeEvent;
-import org.eclipse.swt.SWT;
-import org.eclipse.swt.graphics.Color;
-import org.eclipse.swt.graphics.FontData;
-import org.eclipse.swt.graphics.RGB;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.PartInitException;
 import org.eclipse.ui.editors.text.EditorsUI;
 import org.eclipse.ui.ide.IDE;
-import org.eclipse.ui.internal.editors.text.EditorsPlugin;
 
 import org.eclipse.statet.jcommons.lang.NonNullByDefault;
 import org.eclipse.statet.jcommons.lang.Nullable;
@@ -76,139 +69,57 @@ public class RHelpUIServlet extends RHelpHttpServlet implements IPropertyChangeL
 	static final String HOVER_STYLE= "hover"; //$NON-NLS-1$
 	
 	
-	private static final String[] DEFAULT_MATCH_COLORS= new String[] {
-		".SMATCH-A { background: #ceccf7; }\n",
-		".SMATCH-B { background: #ffffcf; }\n",
-		".SMATCH-C { background: aquamarine; }\n",
-		".SMATCH-D { background: palegreen; }\n",
-		".SMATCH-E { background: coral; }\n",
-		".SMATCH-F { background: wheat; }\n",
-		".SMATCH-G { background: khaki; }\n",
-		".SMATCH-H { background: lime; }\n",
-		".SMATCH-I { background: deepskyblue; }\n",
-		".SMATCH-J { background: plum; }\n",
-	};
-	
-	static Color getDocBackgroundColor() {
-		return nonNullAssert(JFaceResources.getColorRegistry()
-				.get("org.eclipse.statet.workbench.themes.DocViewBackgroundColor") ); //$NON-NLS-1$
-	}
-	
-	static Color getDocForegroundColor() {
-		return nonNullAssert(JFaceResources.getColorRegistry()
-				.get("org.eclipse.statet.workbench.themes.DocViewColor") ); //$NON-NLS-1$
-	}
-	
-	
-	private static void appendCssColor(final StringBuilder sb, final RGB color) {
-		sb.append('#');
-		String s= Integer.toHexString(color.red);
-		if (s.length() == 1) {
-			sb.append('0');
-		}
-		sb.append(s);
-		s= Integer.toHexString(color.green);
-		if (s.length() == 1) {
-			sb.append('0');
-		}
-		sb.append(s);
-		s= Integer.toHexString(color.blue);
-		if (s.length() == 1) {
-			sb.append('0');
-		}
-		sb.append(s);
-	}
-	
-	private static void appendELinkColors(final StringBuilder sb, final RGB foregroundColor) {
-		final RGB hyperlinkColor= nonNullAssert(JFaceResources.getColorRegistry()
-				.getRGB(JFacePreferences.HYPERLINK_COLOR) );
-		final RGB hyperlinkActiveColor= nonNullAssert(JFaceResources.getColorRegistry()
-				.getRGB(JFacePreferences.ACTIVE_HYPERLINK_COLOR) );
-		sb.append("a { color: "); //$NON-NLS-1$
-				appendCssColor(sb, hyperlinkColor);
-				sb.append("; }\n");//$NON-NLS-1$
-		sb.append("a:hover, a:active, a:focus { color: "); //$NON-NLS-1$
-				appendCssColor(sb, hyperlinkActiveColor);
-				sb.append("; }\n"); //$NON-NLS-1$
-		sb.append("a:visited { color: "); //$NON-NLS-1$
-		appendCssColor(sb, new RGB(
-				(hyperlinkColor.red + ((hyperlinkColor.red <= 127) ? +64 : -64)),
-				(hyperlinkColor.green + foregroundColor.green) / 2,
-				(hyperlinkColor.blue + ((hyperlinkColor.blue > 32) ? -32 : +32) + foregroundColor.blue ) / 2 ));
-				sb.append("; }\n"); //$NON-NLS-1$
-	}
-	
-	private static void appendMatchColors(final StringBuilder sb) {
-		int i= 0;
-		final RGB rgb= PreferenceConverter.getColor(
-				EditorsPlugin.getDefault().getPreferenceStore(),
-				"searchResultIndicationColor"); //$NON-NLS-1$
-		if (rgb != null) {
-			sb.append(".SMATCH-A { background: ");
-			appendCssColor(sb, rgb);
-			sb.append("; }\n"); //$NON-NLS-1$
-			i++;
-		}
-		while (i < DEFAULT_MATCH_COLORS.length) {
-			sb.append(DEFAULT_MATCH_COLORS[i++]);
-		}
-	}
-	
-	
 	public static class Browse extends RHelpUIServlet {
 		
 		private static final long serialVersionUID= 1L;
 		
 		@Override
 		protected void collectCss(final StringBuilder sb) {
-			final RGB docBackgroundColor= nonNullAssert(JFaceResources.getColorRegistry()
-					.getRGB("org.eclipse.statet.workbench.themes.DocViewBackgroundColor") ); //$NON-NLS-1$
-			final RGB docForegroundColor= nonNullAssert(JFaceResources.getColorRegistry()
-					.getRGB("org.eclipse.statet.workbench.themes.DocViewColor") ); //$NON-NLS-1$
-			final RGB borderColor= Display.getCurrent()
-					.getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW).getRGB();
+			final var style= new RHelpWorkbenchStyle();
 			
-			{	final FontDescriptor docFontDescr= JFaceResources
-						.getFontDescriptor("org.eclipse.statet.workbench.themes.DocViewFont"); //$NON-NLS-1$
-				final FontData fontData= docFontDescr.getFontData()[0];
-				
-				sb.append("body { font-family: '"); //$NON-NLS-1$
-						sb.append(fontData.getName());
-						sb.append("'; font-size:"); //$NON-NLS-1$
-						sb.append(fontData.getHeight());
-						sb.append("pt; color:"); //$NON-NLS-1$
-						appendCssColor(sb, docForegroundColor);
-						sb.append("; background:"); //$NON-NLS-1$
-						appendCssColor(sb, docBackgroundColor);
-						sb.append("; }\n"); //$NON-NLS-1$
-			}
+			sb.append("body { "); //$NON-NLS-1$
+					style.appendFont(sb, style.getDocFontDescr());
+					sb.append("}\n"); //$NON-NLS-1$
 			
-			appendELinkColors(sb, docForegroundColor);
+			sb.append("@media only screen {\n"); //$NON-NLS-1$
 			
-			sb.append("div.toc a, div.toc a:visited { color: "); //$NON-NLS-1$
-					appendCssColor(sb, docForegroundColor);
-					sb.append("; }\n"); //$NON-NLS-1$
+			sb.append("html {"); //$NON-NLS-1$
+					style.appendRootColors(sb);
+					sb.append("}\n"); //$NON-NLS-1$
+			sb.append("body { " //$NON-NLS-1$
+					+ "margin: "); //$NON-NLS-1$
+							sb.append(LayoutUtils.defaultVSpacing()).append("px "); //$NON-NLS-1$
+							sb.append(LayoutUtils.defaultHSpacing()).append("px; "); //$NON-NLS-1$
+					style.appendScreenColors(sb);
+					sb.append("}\n"); //$NON-NLS-1$
 			
-			sb.append("@media screen {\n"); //$NON-NLS-1$
+			style.appendELinkColors(sb);
 			
-			sb.append("body { margin: "); //$NON-NLS-1$
-					sb.append(LayoutUtils.defaultVSpacing());
-					sb.append("px "); //$NON-NLS-1$
-					sb.append(LayoutUtils.defaultHSpacing());
-					sb.append("px; }\n"); //$NON-NLS-1$
+			sb.append("div.toc { " //$NON-NLS-1$
+					+ "display: inline; " //$NON-NLS-1$
+					+ "float: right; " //$NON-NLS-1$
+					+ "border: 1px solid "); //$NON-NLS-1$
+							appendCssColor(sb, style.getDocBorderColorRGB()).append("; "); //$NON-NLS-1$
+					sb.append("}\n"); //$NON-NLS-1$
 			
-			sb.append("div.toc { display: inline; float: right; border: 1px solid "); //$NON-NLS-1$
-					appendCssColor(sb, borderColor);
+			sb.append("div.toc a, div.toc a:visited { " //$NON-NLS-1$
+					+ "color: "); //$NON-NLS-1$
+							appendCssColor(sb, style.getDocForegroundColorRGB()).append("; "); //$NON-NLS-1$
 					sb.append("; }\n"); //$NON-NLS-1$
 			
-			sb.append("span.mnemonic, div.toc a.mnemonic { text-decoration: underline; }\n"); //$NON-NLS-1$
-			sb.append("hr { border: 0; height: 1px; background: " ); //$NON-NLS-1$
-					appendCssColor(sb, borderColor);
-					sb.append("; }\n"); //$NON-NLS-1$
+			sb.append("span.mnemonic, div.toc a.mnemonic { " //$NON-NLS-1$
+					+ "text-decoration: underline; " //$NON-NLS-1$
+					+ "}\n" ); //$NON-NLS-1$
+			sb.append("hr { " //$NON-NLS-1$
+					+ "border: 0; " //$NON-NLS-1$
+					+ "height: 1px; " //$NON-NLS-1$
+					+ "background: " ); //$NON-NLS-1$
+							appendCssColor(sb, style.getDocBorderColorRGB()).append("; "); //$NON-NLS-1$
+					sb.append("}\n"); //$NON-NLS-1$
 			
-			sb.append("}\n" ); // @media //$NON-NLS-1$
+			sb.append("}\n"); // @media //$NON-NLS-1$
 			
-			appendMatchColors(sb);
+			style.appendMatchColors(sb);
 			
 			super.collectCss(sb);
 		}
@@ -221,37 +132,39 @@ public class RHelpUIServlet extends RHelpHttpServlet implements IPropertyChangeL
 		
 		@Override
 		protected void collectCss(final StringBuilder sb) {
-			final Display display= Display.getCurrent();
-			final RGB docBackgroundColor= nonNullAssert(JFaceResources.getColorRegistry()
-					.getRGB("org.eclipse.statet.workbench.themes.DocViewBackgroundColor") ); //$NON-NLS-1$
-			final RGB docForegroundColor= nonNullAssert(JFaceResources.getColorRegistry()
-					.getRGB("org.eclipse.statet.workbench.themes.DocViewColor") ); //$NON-NLS-1$
+			final var style= new RHelpWorkbenchStyle();
+			
 			final int vIndent= Math.max(1, LayoutUtils.defaultVSpacing() / 4);
 			final int hIndent= Math.max(3, LayoutUtils.defaultHSpacing() / 2);
 			
-			{	final FontDescriptor docFontDescr= JFaceResources.getDialogFontDescriptor();
-				final FontData fontData= docFontDescr.getFontData()[0];
-				sb.append("body { font-family: '"); //$NON-NLS-1$
-						sb.append(fontData.getName());
-						sb.append("'; font-size: "); //$NON-NLS-1$
-						sb.append(fontData.getHeight());
-						sb.append("pt; color: "); //$NON-NLS-1$
-						appendCssColor(sb, docForegroundColor);
-						sb.append("; background: "); //$NON-NLS-1$
-						appendCssColor(sb, docBackgroundColor);
-						sb.append("; margin: 0 "); //$NON-NLS-1$
-						sb.append(hIndent);
-						sb.append("px "); //$NON-NLS-1$
-						sb.append(vIndent);
-						sb.append("px; }\n"); //$NON-NLS-1$
-			}
-			appendELinkColors(sb, docForegroundColor);
+			sb.append("html { "); //$NON-NLS-1$
+					style.appendFont(sb, JFaceResources.getDialogFontDescriptor());
+					style.appendRootColors(sb);
+					sb.append("}\n"); //$NON-NLS-1$
+			sb.append("body { "); //$NON-NLS-1$
+					sb.append("margin: 0 ") //$NON-NLS-1$
+							.append(hIndent).append("px ") //$NON-NLS-1$
+							.append(vIndent).append("px; "); //$NON-NLS-1$
+					style.appendScreenColors(sb);
+					sb.append("}\n"); //$NON-NLS-1$
 			
-			sb.append("h2, h3#description { display: none; }\n"); //$NON-NLS-1$
-			sb.append("h3 { font-size: 90%; margin-bottom: 0.4em; }\n"); //$NON-NLS-1$
-			sb.append("p, pre { margin-top: 0.4em; margin-bottom: 0.4em; }\n" ); //$NON-NLS-1$
+			style.appendELinkColors(sb);
 			
-			sb.append("hr { visibility: hidden; }\n"); //$NON-NLS-1$
+			sb.append("h2, h3#description { " //$NON-NLS-1$
+					+ "display: none; " //$NON-NLS-1$
+					+ "}\n"); //$NON-NLS-1$
+			sb.append("h3 { " //$NON-NLS-1$
+					+ "font-size: 90%; " //$NON-NLS-1$
+					+ "margin-bottom: 0.4em; " //$NON-NLS-1$
+					+ "}\n"); //$NON-NLS-1$
+			sb.append("p, pre { " //$NON-NLS-1$
+					+ "margin-top: 0.4em; " //$NON-NLS-1$
+					+ "margin-bottom: 0.4em; " //$NON-NLS-1$
+					+ "}\n" ); //$NON-NLS-1$
+			
+			sb.append("hr { " //$NON-NLS-1$
+					+ "visibility: hidden; " //$NON-NLS-1$
+					+ "}\n"); //$NON-NLS-1$
 			
 			super.collectCss(sb);
 		}
@@ -263,6 +176,9 @@ public class RHelpUIServlet extends RHelpHttpServlet implements IPropertyChangeL
 	
 	private RHelpRCodeScanner rCodeScanner;
 	
+	private final Runnable updateStyles= this::updateStyles;
+	private boolean updateStyleScheduled;
+	
 	
 	@SuppressWarnings("null")
 	public RHelpUIServlet() {
@@ -283,19 +199,23 @@ public class RHelpUIServlet extends RHelpHttpServlet implements IPropertyChangeL
 		JFaceResources.getFontRegistry().addListener(this);
 		JFaceResources.getColorRegistry().addListener(this);
 		PreferencesUtil.getSettingsChangeNotifier().addChangeListener(this);
-		updateStyles();
+		
+		this.updateStyleScheduled= true;
+		Display.getDefault().syncExec(this.updateStyles);
 	}
 	
 	@Override
 	public void propertyChange(final PropertyChangeEvent event) {
-		if (event.getProperty().equals("org.eclipse.statet.workbench.themes.DocViewFont") //$NON-NLS-1$
-				|| event.getProperty().equals("org.eclipse.statet.workbench.themes.DocViewBackgroundColor") //$NON-NLS-1$
-				|| event.getProperty().equals("org.eclipse.statet.workbench.themes.DocViewColor") //$NON-NLS-1$
-				|| event.getProperty().equals(JFaceResources.DIALOG_FONT)
-				|| event.getProperty().equals(JFacePreferences.HYPERLINK_COLOR)
-				|| event.getProperty().equals(JFacePreferences.ACTIVE_HYPERLINK_COLOR)
-				|| event.getProperty().equals("searchResultIndicationColor") ) { //$NON-NLS-1$
-			updateStyles();
+		if (!this.updateStyleScheduled
+				&& (event.getProperty().equals(RHelpWorkbenchStyle.DOC_BACKGROUND_COLOR_KEY)
+						|| event.getProperty().equals(RHelpWorkbenchStyle.DOC_FOREGROUND_COLOR_KEY)
+						|| event.getProperty().equals(RHelpWorkbenchStyle.DOC_FONT_KEY)
+						|| event.getProperty().equals(JFaceResources.DIALOG_FONT)
+						|| event.getProperty().equals(JFacePreferences.HYPERLINK_COLOR)
+						|| event.getProperty().equals(JFacePreferences.ACTIVE_HYPERLINK_COLOR)
+						|| event.getProperty().equals("searchResultIndicationColor") )) { //$NON-NLS-1$
+			this.updateStyleScheduled= true;
+			Display.getDefault().asyncExec(this.updateStyles);
 		}
 	}
 	
@@ -355,13 +275,10 @@ public class RHelpUIServlet extends RHelpHttpServlet implements IPropertyChangeL
 	
 	
 	private void updateStyles() {
+		this.updateStyleScheduled= false;
+		
 		final StringBuilder sb= new StringBuilder(1024);
-		UIAccess.getDisplay().syncExec(new Runnable() {
-			@Override
-			public void run() {
-				collectCss(sb);
-			}
-		});
+		collectCss(sb);
 		sb.append(".header { display: none; }"); //$NON-NLS-1$
 		this.cssStyle= sb.toString();
 	}
diff --git a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpWorkbenchStyle.java b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpWorkbenchStyle.java
new file mode 100644
index 00000000..558ac056
--- /dev/null
+++ b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpWorkbenchStyle.java
@@ -0,0 +1,246 @@
+/*=============================================================================#
+ # 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.internal.r.ui.rhelp;
+
+import static org.eclipse.statet.jcommons.lang.ObjectUtils.nonNullAssert;
+
+import org.eclipse.jface.preference.JFacePreferences;
+import org.eclipse.jface.preference.PreferenceConverter;
+import org.eclipse.jface.resource.FontDescriptor;
+import org.eclipse.jface.resource.JFaceResources;
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.ScrolledComposite;
+import org.eclipse.swt.graphics.Color;
+import org.eclipse.swt.graphics.FontData;
+import org.eclipse.swt.graphics.RGB;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.ui.internal.editors.text.EditorsPlugin;
+
+import org.eclipse.statet.jcommons.lang.NonNullByDefault;
+
+import org.eclipse.statet.ecommons.ui.swt.ColorUtils;
+import org.eclipse.statet.ecommons.ui.workbench.StylingUtils;
+
+
+@NonNullByDefault
+public class RHelpWorkbenchStyle {
+	
+	
+	static final String DOC_BACKGROUND_COLOR_KEY= "org.eclipse.statet.workbench.themes.DocViewBackgroundColor"; //$NON-NLS-1$
+	static final String DOC_FOREGROUND_COLOR_KEY= "org.eclipse.statet.workbench.themes.DocViewColor"; //$NON-NLS-1$
+	static final String DOC_FONT_KEY= "org.eclipse.statet.workbench.themes.DocViewFont"; //$NON-NLS-1$
+	
+	
+	static Color getDocBackgroundColor() {
+		return nonNullAssert(JFaceResources.getColorRegistry().get(DOC_BACKGROUND_COLOR_KEY));
+	}
+	
+	static Color getDocForegroundColor() {
+		return nonNullAssert(JFaceResources.getColorRegistry().get(DOC_FOREGROUND_COLOR_KEY));
+	}
+	
+	
+	static StringBuilder appendCssColor(final StringBuilder sb, final RGB color) {
+		sb.append('#');
+		String s= Integer.toHexString(color.red);
+		if (s.length() == 1) {
+			sb.append('0');
+		}
+		sb.append(s);
+		s= Integer.toHexString(color.green);
+		if (s.length() == 1) {
+			sb.append('0');
+		}
+		sb.append(s);
+		s= Integer.toHexString(color.blue);
+		if (s.length() == 1) {
+			sb.append('0');
+		}
+		sb.append(s);
+		return sb;
+	}
+	
+	
+	private static final String[] DEFAULT_MATCH_COLORS= new String[] {
+		".SMATCH-A { background: #ceccf7; }\n", //$NON-NLS-1$
+		".SMATCH-B { background: #ffffcf; }\n", //$NON-NLS-1$
+		".SMATCH-C { background: aquamarine; }\n", //$NON-NLS-1$
+		".SMATCH-D { background: palegreen; }\n", //$NON-NLS-1$
+		".SMATCH-E { background: coral; }\n", //$NON-NLS-1$
+		".SMATCH-F { background: wheat; }\n", //$NON-NLS-1$
+		".SMATCH-G { background: khaki; }\n", //$NON-NLS-1$
+		".SMATCH-H { background: lime; }\n", //$NON-NLS-1$
+		".SMATCH-I { background: deepskyblue; }\n", //$NON-NLS-1$
+		".SMATCH-J { background: plum; }\n", //$NON-NLS-1$
+	};
+	
+	
+	private final boolean isThemeStylingRequired;
+	
+	private RGB dialogBackgroundColor;
+	private RGB dialogForegroundColor;
+	
+	private RGB scrollbarBackgroundColor;
+	private RGB scrollbarForegroundColor;
+	private RGB scrollbarArrowColor;
+	
+	private final FontDescriptor docFontDescr;
+	
+	private final RGB docBackgroundColor;
+	private final RGB docForegroundColor;
+	private final RGB docBorderColor;
+	
+	
+	public RHelpWorkbenchStyle() {
+		final Display display= nonNullAssert(Display.getCurrent());
+		this.isThemeStylingRequired= (StylingUtils.isStylingSupported()
+				&& !StylingUtils.isCurrentThemeMatchingSystem(display) );
+		
+		if (this.isThemeStylingRequired) {
+			final var stylingEngine= StylingUtils.getStylingEngine();
+			final var shell= new Shell(display);
+			try {
+				final var composite= new ScrolledComposite(shell, SWT.V_SCROLL);
+				stylingEngine.style(composite);
+				this.dialogBackgroundColor= composite.getBackground().getRGB();
+				this.dialogForegroundColor= composite.getForeground().getRGB();
+			}
+			finally {
+				shell.dispose();
+			}
+		}
+		if (this.dialogBackgroundColor == null || this.dialogForegroundColor == null) {
+			this.dialogBackgroundColor= display.getSystemColor(SWT.COLOR_WIDGET_BACKGROUND).getRGB();
+			this.dialogForegroundColor= display.getSystemColor(SWT.COLOR_WIDGET_FOREGROUND).getRGB();
+		}
+		if (this.isThemeStylingRequired) {
+			switch (StylingUtils.getCurrentThemeType(display)) {
+			case DARK:
+				this.scrollbarBackgroundColor= new RGB(23, 23, 23);
+				this.scrollbarForegroundColor= new RGB(77, 77, 77);
+				this.scrollbarArrowColor= new RGB(103, 103, 103);
+				break;
+			default:
+				this.scrollbarBackgroundColor= this.dialogBackgroundColor;
+				this.scrollbarForegroundColor= ColorUtils.blend(this.dialogForegroundColor, this.dialogBackgroundColor, 0.15f);
+				this.scrollbarArrowColor= ColorUtils.blend(this.dialogForegroundColor, this.dialogBackgroundColor, 0.5f);
+				break;
+			}
+		}
+		
+		this.docFontDescr= nonNullAssert(JFaceResources.getFontDescriptor(DOC_FONT_KEY));
+		
+		this.docBackgroundColor= nonNullAssert(JFaceResources.getColorRegistry()
+				.getRGB(DOC_BACKGROUND_COLOR_KEY) );
+		this.docForegroundColor= nonNullAssert(JFaceResources.getColorRegistry()
+				.getRGB(DOC_FOREGROUND_COLOR_KEY) );
+		this.docBorderColor= Display.getCurrent()
+				.getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW).getRGB();
+	}
+	
+	
+	public FontDescriptor getDocFontDescr() {
+		return this.docFontDescr;
+	}
+	
+	public RGB getDocBackgroundColorRGB() {
+		return this.docBackgroundColor;
+	}
+	
+	public RGB getDocForegroundColorRGB() {
+		return this.docForegroundColor;
+	}
+	
+	public RGB getDocBorderColorRGB() {
+		return this.docBorderColor;
+	}
+	
+	
+	public void appendELinkColors(final StringBuilder sb) {
+		final RGB hyperlinkColor= nonNullAssert(JFaceResources.getColorRegistry()
+				.getRGB(JFacePreferences.HYPERLINK_COLOR) );
+		final RGB hyperlinkActiveColor= nonNullAssert(JFaceResources.getColorRegistry()
+				.getRGB(JFacePreferences.ACTIVE_HYPERLINK_COLOR) );
+		sb.append("a { color: "); //$NON-NLS-1$
+						appendCssColor(sb, hyperlinkColor);
+				sb.append("; }\n");//$NON-NLS-1$
+		sb.append("a:hover, a:active, a:focus { color: "); //$NON-NLS-1$
+						appendCssColor(sb, hyperlinkActiveColor);
+				sb.append("; }\n"); //$NON-NLS-1$
+		sb.append("a:visited { color: "); //$NON-NLS-1$
+				appendCssColor(sb, new RGB(
+						(hyperlinkColor.red + ((hyperlinkColor.red <= 127) ? +64 : -64)),
+						(hyperlinkColor.green + this.docForegroundColor.green) / 2,
+						(hyperlinkColor.blue + ((hyperlinkColor.blue > 32) ? -32 : +32) + this.docForegroundColor.blue ) / 2 ));
+				sb.append("; }\n"); //$NON-NLS-1$
+	}
+	
+	void appendMatchColors(final StringBuilder sb) {
+		int i= 0;
+		final RGB rgb= PreferenceConverter.getColor(EditorsPlugin.getDefault().getPreferenceStore(),
+				"searchResultIndicationColor" ); //$NON-NLS-1$
+		if (rgb != null) {
+			sb.append(".SMATCH-A { background: "); //$NON-NLS-1$
+			appendCssColor(sb, rgb);
+			sb.append("; }\n"); //$NON-NLS-1$
+			i++;
+		}
+		while (i < DEFAULT_MATCH_COLORS.length) {
+			sb.append(DEFAULT_MATCH_COLORS[i++]);
+		}
+	}
+	
+	void appendRootColors(final StringBuilder sb) {
+		sb.append("color: "); //$NON-NLS-1$
+				appendCssColor(sb, this.docForegroundColor).append("; "); //$NON-NLS-1$
+		
+		if (this.isThemeStylingRequired) {
+			sb.append("scrollbar-color: "); //$NON-NLS-1$
+					appendCssColor(sb, this.scrollbarForegroundColor).append(" "); //$NON-NLS-1$
+					appendCssColor(sb, this.scrollbarBackgroundColor).append(" ;"); //$NON-NLS-1$
+			// IE
+			sb.append("scrollbar-track-color: "); //$NON-NLS-1$
+					appendCssColor(sb, this.scrollbarBackgroundColor).append("; "); //$NON-NLS-1$
+			sb.append("scrollbar-base-color: "); //$NON-NLS-1$
+					appendCssColor(sb, this.scrollbarBackgroundColor).append("; "); //$NON-NLS-1$
+			sb.append("scrollbar-face-color: "); //$NON-NLS-1$
+					appendCssColor(sb, this.scrollbarForegroundColor).append("; "); //$NON-NLS-1$
+			sb.append("scrollbar-arrow-color: "); //$NON-NLS-1$
+					appendCssColor(sb, this.scrollbarArrowColor).append("; "); //$NON-NLS-1$
+		}
+	}
+	
+	void appendScreenColors(final StringBuilder sb) {
+		sb.append("color: "); //$NON-NLS-1$
+				appendCssColor(sb, this.docForegroundColor).append("; "); //$NON-NLS-1$
+		sb.append("background: "); //$NON-NLS-1$
+				appendCssColor(sb, this.docBackgroundColor).append("; "); //$NON-NLS-1$
+	}
+	
+	void appendDialogColors(final StringBuilder sb) {
+		sb.append("background: "); //$NON-NLS-1$
+				appendCssColor(sb, this.dialogBackgroundColor).append("; "); //$NON-NLS-1$
+		sb.append("color: "); //$NON-NLS-1$
+				appendCssColor(sb, this.dialogForegroundColor).append("; "); //$NON-NLS-1$
+	}
+	
+	void appendFont(final StringBuilder sb, final FontDescriptor fontDescription) {
+		final FontData fontData= fontDescription.getFontData()[0];
+		sb.append("font-family: '").append(fontData.getName()).append("'; "); //$NON-NLS-1$ //$NON-NLS-2$
+		sb.append("font-size: ").append(fontData.getHeight()).append("pt; "); //$NON-NLS-1$ //$NON-NLS-2$
+	}
+	
+}