Java tutorial
/******************************************************************************* * Copyright (c) 2012 Arapiki Solutions Inc. * 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: * "Peter Smith <psmith@arapiki.com>" - initial API and * implementation and/or initial documentation *******************************************************************************/ package com.buildml.eclipse.utils; import org.eclipse.jface.viewers.TreeViewer; import org.eclipse.jface.viewers.Viewer; import org.eclipse.jface.viewers.ViewerFilter; import org.eclipse.swt.SWT; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Tree; import org.eclipse.swt.widgets.TreeItem; import org.eclipse.swt.widgets.Widget; /** * A VisibilityTreeViewer is the same as a TreeViewer, but has special features for * hiding certain elements. A non-visible element can either be removed completely from the * Tree (i.e. filtered out), or can be greyed-out (still visible, but obviously not selected). * * @author "Peter Smith <psmith@arapiki.com>" */ public class VisibilityTreeViewer extends TreeViewer { /*=====================================================================================* * FIELDS/TYPES *=====================================================================================*/ /** * The externally-registered IVisibilityProvider used by this VisibilityTreeViewer * to indicate whether specific elements should be visible in the Tree control, or * not. */ private IVisibilityProvider visibilityProvider = null; /** The TreeViewer filters to use to reveal all paths */ private ViewerFilter revealViewerFilters[]; /** The TreeViewer filters to use to hide invisible paths */ private ViewerFilter hiddenViewerFilters[]; /** * If true, show hidden elements as being greyed-out. If false, don't * show them at all. */ boolean greyVisibilityMode = true; /*=====================================================================================* * CONSTRUCTORS *=====================================================================================*/ /** * Create a new VisibilityTreeViewer class. * @param tree The Tree widget that this TreeViewer will wrap. */ public VisibilityTreeViewer(Tree tree) { super(tree); /* * Filter for revealing invisible elements so that they can be shown greyed out * (actually, this disables all filters). */ revealViewerFilters = new ViewerFilter[0]; /* Filter for hiding non-visible elements so they won't be seen at all. */ hiddenViewerFilters = new ViewerFilter[1]; hiddenViewerFilters[0] = new ViewerFilter() { public boolean select(Viewer viewer, Object parentElement, Object element) { return visibilityProvider.isVisible(element); } }; /* disabled greyed-out mode */ setGreyVisibilityMode(false); } /*=====================================================================================* * PUBLIC METHODS *=====================================================================================*/ /** * For a given TreeViewer element, set its visibility state. A visible element will appear, * as normal, but a non-visible element will either be greyed out, or not render at all. * * @param element The element to be made visible or non-visible. * @param state True to make it visible, else false. */ public void setVisibility(Object element, boolean state) { /* * First, ensure that there's an underlying model, otherwise everything * should be considered to be selected. */ if (visibilityProvider == null) { return; } /* Set visibility of this element in the underlying model. */ visibilityProvider.setVisibility(element, state); /* refresh the whole TreeViewer so that things appear/disappear/re-colour */ Display.getCurrent().asyncExec(new Runnable() { public void run() { refresh(); } }); } /*-------------------------------------------------------------------------------------*/ /** * Set this viewer's visibility provider class. This provider informs the TreeViewer * which elements in the Tree are to be visible (or non-greyed-out) versus being * invisible (or greyed-out). * * @param visibilityProvider An external provider class (implementing IVisibilityProvider). */ public void setVisibilityProvider(IVisibilityProvider visibilityProvider) { this.visibilityProvider = visibilityProvider; } /*-------------------------------------------------------------------------------------*/ /** * Specify whether this TreeViewer should render non-visible elements using * grey font, or whether they should not be rendered at all. * @param greyVisibility True if non-visible element should be greyed out, * or false if they should not be shown at all. */ public void setGreyVisibilityMode(boolean greyVisibility) { if (greyVisibility) { /* disable the TreeViewer filter, so we'll see the non-visible element */ setFilters(revealViewerFilters); } else { setFilters(hiddenViewerFilters); } this.greyVisibilityMode = greyVisibility; } /*-------------------------------------------------------------------------------------*/ /** * Determine whether this TreeViewer will show non-visible elements using a grey font, * as opposed to not rendering them at all. * @return True if non-visible element are being greyed-out, else false. */ public boolean getGreyVisibilityMode() { return greyVisibilityMode; } /*=====================================================================================* * PROTECTED METHODS *=====================================================================================*/ /* * Overrides the parent class's doUpdateItem(). We use the visibility provider object * (if it exists) to colour the widget appropriately. */ protected void doUpdateItem(Widget widget, Object element, boolean fullMap) { /* invoke the super class to do most of the work */ super.doUpdateItem(widget, element, fullMap); /* * now, if there's a filter registered, ask it whether this element * should be highlighted */ if ((visibilityProvider != null) && (widget instanceof TreeItem)) { setWidgetHighlight((TreeItem) widget, visibilityProvider.isVisible(element)); } } /*=====================================================================================* * PRIVATE METHODS *=====================================================================================*/ /** * Internal method for setting the colour of a widget (to black or grey), depending * on whether the corresponding tree element is visible or not. * @param item The Widget to be coloured. * @param state True to highlight the widget with black, else false to grey it out. */ private void setWidgetHighlight(TreeItem item, boolean state) { if (state) { item.setForeground(Display.getCurrent().getSystemColor(SWT.COLOR_BLACK)); } else { item.setForeground(Display.getCurrent().getSystemColor(SWT.COLOR_GRAY)); } } /*-------------------------------------------------------------------------------------*/ }