com.google.dart.tools.ui.internal.util.DartUIHelp.java Source code

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Here is the source code for com.google.dart.tools.ui.internal.util.DartUIHelp.java

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/*
 * Copyright (c) 2011, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.tools.ui.internal.util;

import com.google.dart.tools.core.model.DartElement;
import com.google.dart.tools.core.model.DartModelException;
import com.google.dart.tools.ui.DartToolsPlugin;
import com.google.dart.tools.ui.internal.actions.ActionUtil;
import com.google.dart.tools.ui.internal.actions.SelectionConverter;
import com.google.dart.tools.ui.internal.text.editor.DartEditor;

import org.eclipse.core.runtime.CoreException;
import org.eclipse.help.HelpSystem;
import org.eclipse.help.IContext;
import org.eclipse.help.IContextProvider;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.HelpEvent;
import org.eclipse.swt.events.HelpListener;
import org.eclipse.ui.IWorkbenchPart;

public class DartUIHelp {

    private static class JavaUIHelpContextProvider implements IContextProvider {
        private String fId;
        private Object[] fSelected;

        public JavaUIHelpContextProvider(String id, Object[] selected) {
            fId = id;
            fSelected = selected;
        }

        @Override
        public IContext getContext(Object target) {
            IContext context = HelpSystem.getContext(fId);
            if (fSelected != null && fSelected.length > 0) {
                try {
                    context = new DartDocHelpContext(context, fSelected);
                } catch (DartModelException e) {
                    // since we are updating the UI with async exec it
                    // can happen that the element doesn't exist anymore
                    // but we are still showing it in the user interface
                    if (!e.isDoesNotExist()) {
                        DartToolsPlugin.log(e);
                    }
                }
            }
            return context;
        }

        @Override
        public int getContextChangeMask() {
            return SELECTION;
        }

        @Override
        public String getSearchExpression(Object target) {
            return null;
        }
    }

    private static class JavaUIHelpListener implements HelpListener {

        private StructuredViewer fViewer;
        private String fContextId;
        private DartEditor fEditor;

        public JavaUIHelpListener(DartEditor editor, String contextId) {
            fContextId = contextId;
            fEditor = editor;
        }

        public JavaUIHelpListener(StructuredViewer viewer, String contextId) {
            fViewer = viewer;
            fContextId = contextId;
        }

        /*
         * @see HelpListener#helpRequested(HelpEvent)
         */
        @Override
        public void helpRequested(HelpEvent e) {
            try {
                Object[] selected = null;
                if (fViewer != null) {
                    ISelection selection = fViewer.getSelection();
                    if (selection instanceof IStructuredSelection) {
                        selected = ((IStructuredSelection) selection).toArray();
                    }
                } else if (fEditor != null) {
                    DartElement input = SelectionConverter.getInput(fEditor);
                    if (ActionUtil.isOnBuildPath(input)) {
                        selected = SelectionConverter.codeResolve(fEditor);
                    }
                }
                DartDocHelpContext.displayHelp(fContextId, selected);
            } catch (CoreException x) {
                DartToolsPlugin.log(x);
            }
        }
    }

    /**
     * Creates and returns a help context provider for the given part.
     * 
     * @param part the part for which to create the help context provider
     * @param contextId the optional context ID used to retrieve static help
     * @return the help context provider
     */
    public static IContextProvider getHelpContextProvider(IWorkbenchPart part, String contextId) {
        IStructuredSelection selection;
        try {
            selection = SelectionConverter.getStructuredSelection(part);
        } catch (DartModelException ex) {
            DartToolsPlugin.log(ex);
            selection = StructuredSelection.EMPTY;
        }
        Object[] elements = selection.toArray();
        return new JavaUIHelpContextProvider(contextId, elements);
    }

    public static void setHelp(DartEditor editor, StyledText text, String contextId) {
        JavaUIHelpListener listener = new JavaUIHelpListener(editor, contextId);
        text.addHelpListener(listener);
    }

    public static void setHelp(StructuredViewer viewer, String contextId) {
        JavaUIHelpListener listener = new JavaUIHelpListener(viewer, contextId);
        viewer.getControl().addHelpListener(listener);
    }
}