Link with Selection Action for Help View toolbar is implemented.

This is similar to JDT Package Explorer's 'Link with Editor' Action. We
will refresh the Help View input based on selection if this Action is
enabled.

see #1874

Author: raghucssit

ua/org.eclipse.help.base/src/org/eclipse/help/internal/base/IHelpActivitySupport.java

@@ -57,6 +57,14 @@ public interface IHelpActivitySupport {
 
 	public void setFilteringEnabled(boolean enabled);
 
+	public default boolean isLinkWithSelectionEnabled() {
+		return true;
+	}
+
+	public default void setLinkWithSelection(boolean enabled) {
+		// does nothing by default
+	}
+
 	public boolean isUserCanToggleFiltering();
 
 	/**

ua/org.eclipse.help.ui/icons/elcl16/synced.svg

@@ -21,6 +21,7 @@
 import org.eclipse.core.runtime.IProduct;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.core.runtime.preferences.IEclipsePreferences;
+import org.eclipse.core.runtime.preferences.IPreferencesService;
 import org.eclipse.core.runtime.preferences.InstanceScope;
 import org.eclipse.help.internal.HelpPlugin;
 import org.eclipse.help.internal.base.HelpBasePlugin;
@@ -42,9 +43,12 @@ public class HelpActivitySupport implements IHelpActivitySupport {
 	private static final String SHOW_DISABLED_ACTIVITIES_ON = "on"; //$NON-NLS-1$
 //	private static final String SHOW_DISABLED_ACTIVITIES_ALWAYS = "always"; //$NON-NLS-1$
 
+	private static final String PREF_KEY_SYNC_SEL = "linkWithSelection"; //$NON-NLS-1$
+
 	private final IWorkbenchActivitySupport activitySupport;
 	private boolean userCanToggleFiltering;
 	private boolean filteringEnabled;
+	private boolean linkWithSelection;
 	private final ActivityDescriptor activityDescriptor;
 
 	static class ActivityDescriptor {
@@ -122,8 +126,9 @@ public HelpActivitySupport(IWorkbench workbench) {
 		activitySupport = workbench.getActivitySupport();
 		activityDescriptor = new ActivityDescriptor();
 
+		IPreferencesService prefService = Platform.getPreferencesService();
 		String showDisabledActivities =
-			Platform.getPreferencesService().getString(HelpBasePlugin.PLUGIN_ID, PREF_KEY_SHOW_DISABLED_ACTIVITIES, "", null); //$NON-NLS-1$
+			prefService.getString(HelpBasePlugin.PLUGIN_ID, PREF_KEY_SHOW_DISABLED_ACTIVITIES, "", null); //$NON-NLS-1$
 		userCanToggleFiltering = SHOW_DISABLED_ACTIVITIES_OFF
 				.equalsIgnoreCase(showDisabledActivities)
 				|| SHOW_DISABLED_ACTIVITIES_ON
@@ -136,6 +141,8 @@ public HelpActivitySupport(IWorkbench workbench) {
 				|| SHOW_DISABLED_ACTIVITIES_NEVER
 						.equalsIgnoreCase(showDisabledActivities);
 		filteringEnabled = filteringEnabled && isWorkbenchFiltering();
+
+		linkWithSelection = prefService.getBoolean(HelpBasePlugin.PLUGIN_ID, PREF_KEY_SYNC_SEL, true, null);
 	}
 
 	@Override
@@ -162,6 +169,22 @@ public void setFilteringEnabled(boolean enabled) {
 		}
 	}
 
+	@Override
+	public boolean isLinkWithSelectionEnabled() {
+		return linkWithSelection;
+	}
+
+	@Override
+	public void setLinkWithSelection(boolean syncSel) {
+		this.linkWithSelection = syncSel;
+		IEclipsePreferences prefs = InstanceScope.INSTANCE.getNode(HelpBasePlugin.PLUGIN_ID);
+		prefs.putBoolean(PREF_KEY_SYNC_SEL, syncSel);
+		try {
+			prefs.flush();
+		} catch (BackingStoreException e) {
+		}
+	}
+
 	@Override
 	public boolean isUserCanToggleFiltering() {
 		return userCanToggleFiltering;

ua/org.eclipse.help.ui/src/org/eclipse/help/ui/internal/HelpActivitySupport.java

@@ -55,6 +55,7 @@ public interface IHelpUIConstants {
 	public static final String IMAGE_CLOSE_HOT = "elcl16/close_hot.svg"; //$NON-NLS-1$
 	public static final String IMAGE_SYNC_TOC = "elcl16/synch_toc_nav.svg"; //$NON-NLS-1$
 	public static final String IMAGE_SHOW_ALL = "elcl16/show_all.svg"; //$NON-NLS-1$
+	public static final String IMAGE_SYNC_SEL = "elcl16/synced.svg"; //$NON-NLS-1$
 	public static final String IMAGE_DOC_OVR = "ovr16/doc_co.svg"; //$NON-NLS-1$
 	public static final String IMAGE_SCOPE_SET = "obj16/scopeset_obj.svg"; //$NON-NLS-1$
 	public static final String IMAGE_SEARCH_WIZ = "wizban/newsearch_wiz.svg"; //$NON-NLS-1$

ua/org.eclipse.help.ui/src/org/eclipse/help/ui/internal/IHelpUIConstants.java

@@ -147,6 +147,7 @@ private Messages() {
 	public static String RootScopePage_desc;
 	public static String AllTopicsPart_collapseAll_tooltip;
 	public static String AllTopicsPart_showAll_tooltip;
+	public static String LinkWithSelection_tooltip;
 	public static String BookmarksPart_savedTopics;
 	public static String BookmarksPart_delete;
 	public static String BookmarksPart_deleteAll;

ua/org.eclipse.help.ui/src/org/eclipse/help/ui/internal/Messages.java

@@ -182,6 +182,7 @@ RootScopePage_name=Na&me:
 RootScopePage_desc=Descri&ption:
 AllTopicsPart_collapseAll_tooltip=Collapse All
 AllTopicsPart_showAll_tooltip = Show All Topics
+LinkWithSelection_tooltip = Link with Selection
 BookmarksPart_savedTopics=Saved Topics
 BookmarksPart_delete=&Delete
 BookmarksPart_deleteAll = D&elete All