bundles/org.eclipse.e4.ui.css.swt/src/org/eclipse/e4/ui/css/swt/properties/custom/CSSPropertyUnselectedTabsSWTHandler.java

/*******************************************************************************
 * Copyright (c) 2010, 2018 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
 *******************************************************************************/
package org.eclipse.e4.ui.css.swt.properties.custom;

import org.eclipse.e4.ui.css.core.dom.properties.Gradient;
import org.eclipse.e4.ui.css.core.engine.CSSEngine;
import org.eclipse.e4.ui.css.swt.helpers.CSSSWTColorHelper;
import org.eclipse.e4.ui.css.swt.properties.AbstractCSSPropertySWTHandler;
import org.eclipse.e4.ui.internal.css.swt.ICTabRendering;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.CTabFolder;
import org.eclipse.swt.custom.CTabFolderRenderer;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Listener;
import org.w3c.dom.css.CSSValue;

public class CSSPropertyUnselectedTabsSWTHandler extends AbstractCSSPropertySWTHandler {
	private static final String UNSELECTED_TABS_COLOR_PROP = "swt-unselected-tabs-color";

	private static final String RESIZE_LISTENER = "CSSPropertyUnselectedTabsSWTHandler.resizeListener";

	@Override
	protected void applyCSSProperty(Control control, String property,
			CSSValue value, String pseudo, CSSEngine engine) throws Exception {
		if (!(control instanceof CTabFolder)
				|| !isUnselectedTabsColorProp(property)) {
			return;
		}
		CTabFolder folder = ((CTabFolder) control);
		CTabFolderRenderer renderer = folder.getRenderer();
		if (!(renderer instanceof ICTabRendering)) {
			return;
		}

		if (value.getCssValueType() == CSSValue.CSS_PRIMITIVE_VALUE) {
			Color color = (Color) engine.convert(value, Color.class,
					control.getDisplay());
			((ICTabRendering) renderer).setUnselectedTabsColor(color);
			folder.setBackground(color);
			removeResizeEventListener(folder);
			return;
		}
		if (value.getCssValueType() == CSSValue.CSS_VALUE_LIST) {
			Gradient grad = (Gradient) engine.convert(value, Gradient.class, control.getDisplay());
			if (grad == null) {
				return;
			}
			Color[] colors = null;
			int[] percents = null;
			if (!grad.getValues().isEmpty()) {
				colors = CSSSWTColorHelper.getSWTColors(grad,
						control.getDisplay(), engine);
				percents = CSSSWTColorHelper.getPercents(grad);
			}
			((ICTabRendering) renderer)
			.setUnselectedTabsColor(colors, percents);
			folder.setBackground(colors, percents, true);
			appendResizeEventListener(folder);
		}
	}


	@Override
	protected String retrieveCSSProperty(Control control, String property,
			String pseudo, CSSEngine engine) throws Exception {
		// TODO Auto-generated method stub
		return null;
	}

	private boolean isUnselectedTabsColorProp(String property) {
		return UNSELECTED_TABS_COLOR_PROP.equals(property);
	}

	// TODO: It needs to be refactored when the Bug 33276 gets fixed
	private void appendResizeEventListener(CTabFolder folder) {
		if (hasResizeEventListener(folder)) {
			return;
		}

		final Listener resizeListener = event -> {
			CTabFolder folder1 = (CTabFolder) event.widget;
			for (Control child : folder1.getChildren()) {
				if (isReskinRequired(child)) {
					child.reskin(SWT.NONE);
				}
			}
		};

		folder.addListener(SWT.Resize, resizeListener);
		folder.setData(RESIZE_LISTENER, resizeListener);
		folder.addDisposeListener(new DisposeListener() {
			@Override
			public void widgetDisposed(DisposeEvent e) {
				e.widget.removeListener(SWT.Resize, resizeListener);
			}
		});
	}

	private void removeResizeEventListener(CTabFolder folder) {
		Object obj = folder.getData(RESIZE_LISTENER);
		if (obj instanceof Listener) {
			folder.removeListener(SWT.Resize, (Listener) obj);
			folder.setData(RESIZE_LISTENER, null);
		}
	}

	private boolean hasResizeEventListener(CTabFolder folder) {
		return folder.getData(RESIZE_LISTENER) instanceof Listener;
	}

	private boolean isReskinRequired(Control control) {
		if (control instanceof Composite) {
			Composite composite = (Composite) control;
			return composite.isVisible() && composite.getChildren().length > 0;
		}
		return false;
	}
}