Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2008 IBM Corporation and others. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package com.binge.workforce.widgets.internal; import java.util.Arrays; import java.util.List; import org.eclipse.e4.demo.simpleide.dialogs.internal.Messages; import org.eclipse.e4.demo.simpleide.services.IImageService; import org.eclipse.e4.demo.simpleide.services.IImageService.IImagePool; import org.eclipse.e4.demo.simpleide.sharedimages.SharedImageKeys; import org.eclipse.jface.action.Action; import org.eclipse.jface.action.IMenuManager; import org.eclipse.jface.action.IToolBarManager; import org.eclipse.jface.resource.ImageDescriptor; import org.eclipse.jface.viewers.ISelectionChangedListener; import org.eclipse.jface.viewers.IStructuredSelection; import org.eclipse.jface.viewers.SelectionChangedEvent; import org.eclipse.jface.viewers.StructuredSelection; import org.eclipse.jface.viewers.TreeViewer; /** * Implements a simple web style navigation metaphor for a <code>TreeViewer</code>. * Home, back, and "drill into" functions are supported for the viewer, * <p> * To use the <code>DrillDownAdapter</code> .. * </p> * <ul> * <li>Create an instance of <code>TreeViewer</code>. </li> * <li>Create a <code>DrillDownAdapter</code> for the viewer. </li> * <li>Create a container for your viewer with a toolbar or a popup menu. * Add actions for "goBack", "goHome", and "goInto" to either one by calling * </code>addNavigationActions</code> with the popup menu or toolbar.</li> * </ol> * <p> * If the input for the underlying viewer is changed by something other than the * adapter the <code>reset</code> method should be called. This will clear * the drill stack and update the navigation buttons to reflect the new * state of the underlying viewer. * </p> * </p> */ public class DrillDownAdapter implements ISelectionChangedListener { private TreeViewer fChildTree; private DrillStack fDrillStack; private Action homeAction; private Action backAction; private Action forwardAction; /** * Allocates a new DrillDownTreePart. * * @param tree the target tree for refocusing */ public DrillDownAdapter(TreeViewer tree, IImageService imageService) { pool = imageService.getControlPool(tree.getControl()); fDrillStack = new DrillStack(); fChildTree = tree; } /** * Adds actions for "go back", "go home", and "go into" to a menu manager. * * @param manager is the target manager to update */ public void addNavigationActions(IMenuManager manager) { createActions(); manager.add(homeAction); manager.add(backAction); manager.add(forwardAction); updateNavigationButtons(); } /** * Adds actions for "go back", "go home", and "go into" to a tool bar manager. * * @param toolBar is the target manager to update */ public void addNavigationActions(IToolBarManager toolBar) { createActions(); toolBar.add(homeAction); toolBar.add(backAction); toolBar.add(forwardAction); updateNavigationButtons(); } /** * Returns whether expansion is possible for the current selection. This * will only be true if it has children. * * @param element the object to test for expansion * @return <code>true</code> if expansion is possible; otherwise * return <code>false</code */ public boolean canExpand(Object element) { return fChildTree.isExpandable(element); } /** * Returns whether "go back" is possible for child tree. This is only possible * if the client has performed one or more drilling operations. * * @return <code>true</code> if "go back" is possible; <code>false</code> otherwise */ public boolean canGoBack() { return fDrillStack.canGoBack(); } /** * Returns whether "go home" is possible for child tree. This is only possible * if the client has performed one or more drilling operations. * * @return <code>true</code> if "go home" is possible; <code>false</code> otherwise */ public boolean canGoHome() { return fDrillStack.canGoHome(); } /** * Returns whether "go into" is possible for child tree. This is only possible * if the current selection in the client has one item and it has children. * * @return <code>true</code> if "go into" is possible; <code>false</code> otherwise */ public boolean canGoInto() { IStructuredSelection oSelection = (IStructuredSelection) fChildTree.getSelection(); if (oSelection == null || oSelection.size() != 1) { return false; } Object anElement = oSelection.getFirstElement(); return canExpand(anElement); } /** * Create the actions for navigation. * */ private void createActions() { // Only do this once. if (homeAction != null) { return; } // Home. homeAction = new Action(Messages.GoHome_text) { public void run() { goHome(); } }; homeAction.setToolTipText(Messages.GoHome_toolTip); homeAction.setImageDescriptor( ImageDescriptor.createFromImage(pool.getImageUnchecked(SharedImageKeys.IMG_TOOL_HOME_NAV))); // Back. backAction = new Action(Messages.GoBack_text) { public void run() { goBack(); } }; backAction.setToolTipText(Messages.GoBack_toolTip); backAction.setImageDescriptor( ImageDescriptor.createFromImage(pool.getImageUnchecked(SharedImageKeys.IMG_TOOL_BACK))); backAction.setDisabledImageDescriptor( ImageDescriptor.createFromImage(pool.getImageUnchecked(SharedImageKeys.IMG_TOOL_BACK_DISABLED))); // Forward. forwardAction = new Action(Messages.GoInto_text) { public void run() { goInto(); } }; forwardAction.setToolTipText(Messages.GoInto_toolTip); forwardAction.setImageDescriptor( ImageDescriptor.createFromImage(pool.getImageUnchecked(SharedImageKeys.IMG_TOOL_FORWARD))); forwardAction.setDisabledImageDescriptor( ImageDescriptor.createFromImage(pool.getImageUnchecked(SharedImageKeys.IMG_TOOL_FORWARD_DISABLED))); // Update the buttons when a selection change occurs. fChildTree.addSelectionChangedListener(this); updateNavigationButtons(); } /** * Expands the given items in the tree. The list of items passed should be * derived by calling <code>getExpanded</code>. * * @param items is a list of items within the tree which should be expanded */ private void expand(List items) { fChildTree.setExpandedElements(items.toArray()); } /** * Returns a list of elements corresponding to expanded nodes in * child tree. * * @return a list of expandd elements */ private List getExpanded() { return Arrays.asList(fChildTree.getExpandedElements()); } /** * Reverts the input for the tree back to the state when <code>goInto</code> * was last called. * <p> * A frame is removed from the drill stack. Then that frame is used to reset the * input and expansion state for the child tree. * </p> */ public void goBack() { Object currentInput = fChildTree.getInput(); DrillFrame oFrame = fDrillStack.goBack(); Object input = oFrame.getElement(); fChildTree.setInput(input); expand(oFrame.getExpansion()); // if there was a selection, it should have been preserved, // but if not, select the element that was drilled into if (fChildTree.getSelection().isEmpty()) { fChildTree.setSelection(new StructuredSelection(currentInput), true); } updateNavigationButtons(); } /** * Reverts the input for the tree back to the state when the adapter was * created. * <p> * All of the frames are removed from the drill stack. Then the oldest frame is * used to reset the input and expansion state for the child tree. * </p> */ public void goHome() { Object currentInput = fChildTree.getInput(); DrillFrame oFrame = fDrillStack.goHome(); Object input = oFrame.getElement(); fChildTree.setInput(input); expand(oFrame.getExpansion()); // if there was a selection, it should have been preserved, // but if not, select the element that was last drilled into if (fChildTree.getSelection().isEmpty()) { fChildTree.setSelection(new StructuredSelection(currentInput), true); } updateNavigationButtons(); } /** * Sets the input for the tree to the current selection. * <p> * The current input and expansion state are saved in a frame and added to the * drill stack. Then the input for the tree is changed to be the current selection. * The expansion state for the tree is maintained during the operation. * </p><p> * On return the client may revert back to the previous state by invoking * <code>goBack</code> or <code>goHome</code>. * </p> */ public void goInto() { IStructuredSelection sel = (IStructuredSelection) fChildTree.getSelection(); Object element = sel.getFirstElement(); goInto(element); } /** * Sets the input for the tree to a particular item in the tree. * <p> * The current input and expansion state are saved in a frame and added to the * drill stack. Then the input for the tree is changed to be <code>newInput</code>. * The expansion state for the tree is maintained during the operation. * </p><p> * On return the client may revert back to the previous state by invoking * <code>goBack</code> or <code>goHome</code>. * </p> * * @param newInput the new input element */ public void goInto(Object newInput) { // If we can drill .. if (canExpand(newInput)) { // Save the old state. Object oldInput = fChildTree.getInput(); List expandedList = getExpanded(); fDrillStack.add(new DrillFrame(oldInput, "null", expandedList));//$NON-NLS-1$ // Install the new state. fChildTree.setInput(newInput); expand(expandedList); updateNavigationButtons(); } } /** * Resets the drill down adapter. * <p> * This method is typically called when the input for the underlying view * is reset by something other than the adapter. * On return the drill stack has been cleared and the navigation buttons * reflect the new state of the underlying viewer. * </p> */ public void reset() { fDrillStack.reset(); updateNavigationButtons(); } /** * Updates the navigation buttons when a selection change occurs * in the tree. */ public void selectionChanged(SelectionChangedEvent event) { updateNavigationButtons(); } /** * Updates the enabled state for each navigation button. */ protected void updateNavigationButtons() { if (homeAction != null) { homeAction.setEnabled(canGoHome()); backAction.setEnabled(canGoBack()); forwardAction.setEnabled(canGoInto()); } } }