org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/selection/MultiViewerSelectionProvider.java

   1 /*******************************************************************************
   2  * Copyright (C) 2017, Thomas Wolf <thomas.wolf@paranor.ch>
   3  *
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *******************************************************************************/
   9 package org.eclipse.egit.ui.internal.selection;
  10
  11 import java.util.ArrayList;
  12 import java.util.List;
  13
  14 import org.eclipse.core.runtime.Assert;
  15 import org.eclipse.jface.viewers.IPostSelectionProvider;
  16 import org.eclipse.jface.viewers.ISelection;
  17 import org.eclipse.jface.viewers.ISelectionChangedListener;
  18 import org.eclipse.jface.viewers.SelectionChangedEvent;
  19 import org.eclipse.jface.viewers.StructuredSelection;
  20 import org.eclipse.jface.viewers.Viewer;
  21 import org.eclipse.swt.SWT;
  22 import org.eclipse.swt.widgets.Control;
  23 import org.eclipse.swt.widgets.Listener;
  24
  25 /**
  26  * A {@link IPostSelectionProvider} for views with several viewers, tracking
  27  * focus changes among the viewers to supply the correct selection.
  28  */
  29 public class MultiViewerSelectionProvider extends AbstractSelectionProvider {
  30
  31         private final List<Viewer> viewers = new ArrayList<>();
  32
  33         private final Listener focusHook = event -> {
  34                 if (event.type == SWT.FocusIn && event.widget instanceof Control) {
  35                         focusChanged((Control) event.widget);
  36                 }
  37         };
  38
  39         private final ISelectionChangedListener selectionHook = event -> selectionChanged(
  40                         event);
  41
  42         private final ISelectionChangedListener postSelectionHook = event -> postSelectionChanged(
  43                         event);
  44
  45         private Viewer currentViewer;
  46
  47         /**
  48          * Creates a new {@link MultiViewerSelectionProvider} for the given viewers.
  49          * The first viewer given is assumed to be the one that's focused initially.
  50          *
  51          * @param providers
  52          *            that contribute to this selection provider
  53          */
  54         public MultiViewerSelectionProvider(Viewer... providers) {
  55                 Assert.isLegal(providers != null && providers.length > 0);
  56                 for (Viewer viewer : providers) {
  57                         Assert.isLegal(viewer != null);
  58                         viewers.add(viewer);
  59                         viewer.getControl().addListener(SWT.FocusIn, focusHook);
  60                         viewer.addSelectionChangedListener(selectionHook);
  61                         if (viewer instanceof IPostSelectionProvider) {
  62                                 ((IPostSelectionProvider) viewer)
  63                                                 .addPostSelectionChangedListener(postSelectionHook);
  64                         }
  65                         if (currentViewer == null) {
  66                                 currentViewer = viewer;
  67                         }
  68                 }
  69         }
  70
  71         private void focusChanged(Control control) {
  72                 for (Viewer viewer : viewers) {
  73                         if (control == viewer.getControl()) {
  74                                 if (viewer != currentViewer) {
  75                                         currentViewer = viewer;
  76                                         fireSelectionChanged(getSelectionListeners());
  77                                         fireSelectionChanged(getPostSelectionListeners());
  78                                 }
  79                                 return;
  80                         }
  81                 }
  82         }
  83
  84         private void selectionChanged(SelectionChangedEvent event) {
  85                 if (event.getSelectionProvider() == currentViewer) {
  86                         fireSelectionChanged(getSelectionListeners());
  87                 }
  88         }
  89
  90         private void postSelectionChanged(SelectionChangedEvent event) {
  91                 if (event.getSelectionProvider() == currentViewer) {
  92                         fireSelectionChanged(getPostSelectionListeners());
  93                 }
  94         }
  95
  96         @Override
  97         public ISelection getSelection() {
  98                 if (currentViewer != null) {
  99                         return currentViewer.getSelection();
 100                 }
 101                 return StructuredSelection.EMPTY;
 102         }
 103
 104         @Override
 105         public void setSelection(ISelection selection) {
 106                 if (currentViewer != null) {
 107                         currentViewer.setSelection(selection);
 108                 }
 109         }
 110 }