Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2016 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation * Alexander Kurtakov <akurtako@redhat.com> - Bug 459761 *******************************************************************************/ package org.eclipse.jface.viewers; import org.eclipse.core.runtime.Assert; import org.eclipse.core.runtime.ListenerList; import org.eclipse.swt.graphics.Color; import org.eclipse.swt.graphics.Font; import org.eclipse.swt.graphics.Image; /** * A decorating label provider is a label provider which combines * a nested label provider and an optional decorator. * The decorator decorates the label text, image, font and colors provided by * the nested label provider. */ public class DecoratingLabelProvider extends LabelProvider implements IViewerLabelProvider, IColorProvider, IFontProvider, ITreePathLabelProvider { private ILabelProvider provider; private ILabelDecorator decorator; // Need to keep our own list of listeners private ListenerList<ILabelProviderListener> listeners = new ListenerList<>(); private IDecorationContext decorationContext = DecorationContext.DEFAULT_CONTEXT; /** * Creates a decorating label provider which uses the given label decorator * to decorate labels provided by the given label provider. * * @param provider the nested label provider * @param decorator the label decorator, or <code>null</code> if no decorator is to be used initially */ public DecoratingLabelProvider(ILabelProvider provider, ILabelDecorator decorator) { Assert.isNotNull(provider); this.provider = provider; this.decorator = decorator; } /** * The <code>DecoratingLabelProvider</code> implementation of this <code>IBaseLabelProvider</code> method * adds the listener to both the nested label provider and the label decorator. * * @param listener a label provider listener */ @Override public void addListener(ILabelProviderListener listener) { super.addListener(listener); provider.addListener(listener); if (decorator != null) { decorator.addListener(listener); } listeners.add(listener); } /** * The <code>DecoratingLabelProvider</code> implementation of this <code>IBaseLabelProvider</code> method * disposes both the nested label provider and the label decorator. */ @Override public void dispose() { provider.dispose(); if (decorator != null) { decorator.dispose(); } } /** * The <code>DecoratingLabelProvider</code> implementation of this * <code>ILabelProvider</code> method returns the image provided * by the nested label provider's <code>getImage</code> method, * decorated with the decoration provided by the label decorator's * <code>decorateImage</code> method. */ @Override public Image getImage(Object element) { Image image = provider.getImage(element); if (decorator != null) { if (decorator instanceof LabelDecorator) { LabelDecorator ld2 = (LabelDecorator) decorator; Image decorated = ld2.decorateImage(image, element, getDecorationContext()); if (decorated != null) { return decorated; } } else { Image decorated = decorator.decorateImage(image, element); if (decorated != null) { return decorated; } } } return image; } /** * Returns the label decorator, or <code>null</code> if none has been set. * * @return the label decorator, or <code>null</code> if none has been set. */ public ILabelDecorator getLabelDecorator() { return decorator; } /** * Returns the nested label provider. * * @return the nested label provider */ public ILabelProvider getLabelProvider() { return provider; } /** * The <code>DecoratingLabelProvider</code> implementation of this * <code>ILabelProvider</code> method returns the text label provided * by the nested label provider's <code>getText</code> method, * decorated with the decoration provided by the label decorator's * <code>decorateText</code> method. */ @Override public String getText(Object element) { String text = provider.getText(element); if (decorator != null) { if (decorator instanceof LabelDecorator) { LabelDecorator ld2 = (LabelDecorator) decorator; String decorated = ld2.decorateText(text, element, getDecorationContext()); if (decorated != null) { return decorated; } } else { String decorated = decorator.decorateText(text, element); if (decorated != null) { return decorated; } } } return text; } /** * The <code>DecoratingLabelProvider</code> implementation of this * <code>IBaseLabelProvider</code> method returns <code>true</code> if the corresponding method * on the nested label provider returns <code>true</code> or if the corresponding method on the * decorator returns <code>true</code>. */ @Override public boolean isLabelProperty(Object element, String property) { if (provider.isLabelProperty(element, property)) { return true; } if (decorator != null && decorator.isLabelProperty(element, property)) { return true; } return false; } /** * The <code>DecoratingLabelProvider</code> implementation of this <code>IBaseLabelProvider</code> method * removes the listener from both the nested label provider and the label decorator. * * @param listener a label provider listener */ @Override public void removeListener(ILabelProviderListener listener) { super.removeListener(listener); provider.removeListener(listener); if (decorator != null) { decorator.removeListener(listener); } listeners.remove(listener); } /** * Sets the label decorator. * Removes all known listeners from the old decorator, and adds all known listeners to the new decorator. * The old decorator is not disposed. * Fires a label provider changed event indicating that all labels should be updated. * Has no effect if the given decorator is identical to the current one. * * @param decorator the label decorator, or <code>null</code> if no decorations are to be applied */ public void setLabelDecorator(ILabelDecorator decorator) { ILabelDecorator oldDecorator = this.decorator; if (oldDecorator != decorator) { if (oldDecorator != null) { for (ILabelProviderListener l : listeners) { oldDecorator.removeListener(l); } } this.decorator = decorator; if (decorator != null) { for (ILabelProviderListener l : listeners) { decorator.addListener(l); } } fireLabelProviderChanged(new LabelProviderChangedEvent(this)); } } @Override public void updateLabel(ViewerLabel settings, Object element) { ILabelDecorator currentDecorator = getLabelDecorator(); String oldText = settings.getText(); boolean decorationReady = true; if (currentDecorator instanceof IDelayedLabelDecorator) { IDelayedLabelDecorator delayedDecorator = (IDelayedLabelDecorator) currentDecorator; if (!delayedDecorator.prepareDecoration(element, oldText)) { // The decoration is not ready but has been queued for processing decorationReady = false; } } // update icon and label if (decorationReady || oldText == null || settings.getText().length() == 0) { settings.setText(getText(element)); } Image oldImage = settings.getImage(); if (decorationReady || oldImage == null) { settings.setImage(getImage(element)); } if (decorationReady) { updateForDecorationReady(settings, element); } } /** * Decoration is ready. Update anything else for the settings. * @param settings The object collecting the settings. * @param element The Object being decorated. * @since 3.1 */ protected void updateForDecorationReady(ViewerLabel settings, Object element) { if (decorator instanceof IColorDecorator) { IColorDecorator colorDecorator = (IColorDecorator) decorator; settings.setBackground(colorDecorator.decorateBackground(element)); settings.setForeground(colorDecorator.decorateForeground(element)); } if (decorator instanceof IFontDecorator) { settings.setFont(((IFontDecorator) decorator).decorateFont(element)); } } @Override public Color getBackground(Object element) { if (provider instanceof IColorProvider) { return ((IColorProvider) provider).getBackground(element); } return null; } @Override public Font getFont(Object element) { if (provider instanceof IFontProvider) { return ((IFontProvider) provider).getFont(element); } return null; } @Override public Color getForeground(Object element) { if (provider instanceof IColorProvider) { return ((IColorProvider) provider).getForeground(element); } return null; } /** * Return the decoration context associated with this label provider. * It will be passed to the decorator if the decorator is an * instance of {@link LabelDecorator}. * @return the decoration context associated with this label provider * * @since 3.2 */ public IDecorationContext getDecorationContext() { return decorationContext; } /** * Set the decoration context that will be based to the decorator * for this label provider if that decorator implements {@link LabelDecorator}. * @param decorationContext the decoration context. * * @since 3.2 */ public void setDecorationContext(IDecorationContext decorationContext) { Assert.isNotNull(decorationContext); this.decorationContext = decorationContext; } @Override public void updateLabel(ViewerLabel settings, TreePath elementPath) { ILabelDecorator currentDecorator = getLabelDecorator(); String oldText = settings.getText(); Object element = elementPath.getLastSegment(); boolean decorationReady = true; if (currentDecorator instanceof LabelDecorator) { LabelDecorator labelDecorator = (LabelDecorator) currentDecorator; if (!labelDecorator.prepareDecoration(element, oldText, getDecorationContext())) { // The decoration is not ready but has been queued for processing decorationReady = false; } } else if (currentDecorator instanceof IDelayedLabelDecorator) { IDelayedLabelDecorator delayedDecorator = (IDelayedLabelDecorator) currentDecorator; if (!delayedDecorator.prepareDecoration(element, oldText)) { // The decoration is not ready but has been queued for processing decorationReady = false; } } settings.setHasPendingDecorations(!decorationReady); // update icon and label if (provider instanceof ITreePathLabelProvider) { ITreePathLabelProvider pprov = (ITreePathLabelProvider) provider; if (decorationReady || oldText == null || settings.getText().length() == 0) { pprov.updateLabel(settings, elementPath); decorateSettings(settings, elementPath); } } else { if (decorationReady || oldText == null || settings.getText().length() == 0) { settings.setText(getText(element)); } Image oldImage = settings.getImage(); if (decorationReady || oldImage == null) { settings.setImage(getImage(element)); } if (decorationReady) { updateForDecorationReady(settings, element); } } } /** * Decorate the settings * @param settings the settings obtained from the label provider * @param elementPath the element path being decorated */ private void decorateSettings(ViewerLabel settings, TreePath elementPath) { Object element = elementPath.getLastSegment(); if (decorator != null) { if (decorator instanceof LabelDecorator) { LabelDecorator labelDecorator = (LabelDecorator) decorator; String text = labelDecorator.decorateText(settings.getText(), element, getDecorationContext()); if (text != null && text.length() > 0) settings.setText(text); Image image = labelDecorator.decorateImage(settings.getImage(), element, getDecorationContext()); if (image != null) settings.setImage(image); } else { String text = decorator.decorateText(settings.getText(), element); if (text != null && text.length() > 0) settings.setText(text); Image image = decorator.decorateImage(settings.getImage(), element); if (image != null) settings.setImage(image); } if (decorator instanceof IColorDecorator) { IColorDecorator colorDecorator = (IColorDecorator) decorator; Color background = colorDecorator.decorateBackground(element); if (background != null) settings.setBackground(background); Color foreground = colorDecorator.decorateForeground(element); if (foreground != null) settings.setForeground(foreground); } if (decorator instanceof IFontDecorator) { Font font = ((IFontDecorator) decorator).decorateFont(element); if (font != null) settings.setFont(font); } } } }