CSSPropertyUnselectedTabsColorSWTHandler.java

package org.xmind.cathy.internal.css;

import org.eclipse.e4.ui.css.core.dom.properties.Gradient;
import org.eclipse.e4.ui.css.core.dom.properties.ICSSPropertyHandler;
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.Event;
import org.eclipse.swt.widgets.Listener;
import org.w3c.dom.css.CSSValue;
import org.xmind.cathy.internal.ICathyConstants;

@SuppressWarnings("restriction")
public class CSSPropertyUnselectedTabsColorSWTHandler
        extends AbstractCSSPropertySWTHandler {

    private static final String RESIZE_LISTENER = "CSSPropertyUnselectedTabsColorSWTHandler.resizeListener"; //$NON-NLS-1$

    public static final ICSSPropertyHandler INSTANCE = new CSSPropertyUnselectedTabsColorSWTHandler();

    @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(null);
            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(null, null, false);
            appendResizeEventListener(folder);
        }
    }

    @Override
    protected String retrieveCSSProperty(Control control, String property,
            String pseudo, CSSEngine engine) throws Exception {
        return null;
    }

    private boolean isUnselectedTabsColorProp(String property) {
        return ICathyConstants.PROPERTY_UNSELECTED_TABS_COLOR.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 = new Listener() {
            public void handleEvent(Event event) {
                CTabFolder folder = (CTabFolder) event.widget;
                for (Control child : folder.getChildren()) {
                    if (isReskinRequired(child)) {
                        child.reskin(SWT.NONE);
                    }
                }
            }
        };

        folder.addListener(SWT.Resize, resizeListener);
        folder.setData(RESIZE_LISTENER, resizeListener);
        folder.addDisposeListener(new DisposeListener() {
            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;
    }
}