org.eclipse.egit.ui.internal.components.CheckboxLabelProvider.java Source code

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Here is the source code for org.eclipse.egit.ui.internal.components.CheckboxLabelProvider.java

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/*******************************************************************************
 * Copyright (C) 2008, Marek Zawirski <marek.zawirski@gmail.com>
 *
 * 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
 *******************************************************************************/
package org.eclipse.egit.ui.internal.components;

import org.eclipse.core.runtime.Platform;
import org.eclipse.egit.ui.UIIcons;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.resource.LocalResourceManager;
import org.eclipse.jface.resource.ResourceManager;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Shell;

/**
 * Label provider displaying native check boxes images for boolean values.
 * Label-image is centralized.
 * <p>
 * Concrete implementations must provide object to boolean mapping.
 * <p>
 * This implementation is actually workaround for lacking features in
 * TableViewer. It is based on (workaround) snippets&tricks found on Internet.
 */
public abstract class CheckboxLabelProvider extends CenteredImageLabelProvider {
    private static Image createCheckboxImage(final ResourceManager resourceManager, final Control control,
            boolean checked, boolean enabled) {

        String checkboxhack = System.getProperty("egit.swt.checkboxhack"); //$NON-NLS-1$
        if (checkboxhack == null)
            if (Platform.getOS().equals(Platform.OS_MACOSX))
                checkboxhack = "hardwired"; //$NON-NLS-1$
            else
                checkboxhack = "screenshot"; //$NON-NLS-1$

        if (checkboxhack == "hardwired") { //$NON-NLS-1$
            if (enabled) {
                if (checked)
                    return UIIcons.CHECKBOX_ENABLED_CHECKED.createImage();
                return UIIcons.CHECKBOX_ENABLED_UNCHECKED.createImage();
            }
            if (checked)
                return UIIcons.CHECKBOX_DISABLED_CHECKED.createImage();
            return UIIcons.CHECKBOX_DISABLED_UNCHECKED.createImage();
        }

        // else if checkboxhack = "screenshot";

        // FIXME: Shawn says that blinking shell caused by below code is very
        // annoying...(at least on Mac) - anyone knows better workaround?
        final Shell s = new Shell(control.getShell(), SWT.NO_TRIM);
        // Hopefully no platform uses exactly this color because we'll make
        // it transparent in the image.
        final Color greenScreen = resourceManager.createColor(new RGB(222, 223, 224));

        // otherwise we have a default gray color
        s.setBackground(greenScreen);

        final Button b = new Button(s, SWT.CHECK);
        b.setSelection(checked);
        b.setEnabled(enabled);
        b.setBackground(greenScreen);

        // otherwise an image is located in a corner
        b.setLocation(0, 0);
        final Point bSize = b.computeSize(SWT.DEFAULT, SWT.DEFAULT);
        // otherwise an image is stretched by width
        bSize.x = Math.max(bSize.x, bSize.y);
        bSize.y = Math.max(bSize.x, bSize.y);
        b.setSize(bSize);
        s.setSize(bSize);
        s.open();

        final GC gc = new GC(b);
        final Image image = new Image(control.getShell().getDisplay(), bSize.x, bSize.y);
        gc.copyArea(image, 0, 0);
        gc.dispose();
        s.close();

        final ImageData imageData = image.getImageData();
        imageData.transparentPixel = imageData.palette.getPixel(greenScreen.getRGB());
        final Image checkboxImage = resourceManager.createImage(ImageDescriptor.createFromImageData(imageData));
        image.dispose();
        return checkboxImage;
    }

    private final Image imageCheckedEnabled;

    private final Image imageUncheckedEnabled;

    private final Image imageCheckedDisabled;

    private final Image imageUncheckedDisabled;

    private final ResourceManager resourceManager;

    /**
     * Create label provider for provided viewer.
     *
     * @param control
     *            viewer where label provided is used.
     */
    public CheckboxLabelProvider(final Control control) {
        resourceManager = new LocalResourceManager(JFaceResources.getResources());

        imageCheckedEnabled = createCheckboxImage(resourceManager, control, true, true);
        imageUncheckedEnabled = createCheckboxImage(resourceManager, control, false, true);
        imageCheckedDisabled = createCheckboxImage(resourceManager, control, true, false);
        imageUncheckedDisabled = createCheckboxImage(resourceManager, control, false, false);
    }

    @Override
    public void dispose() {
        super.dispose();
        resourceManager.dispose();
    }

    @Override
    protected Image getImage(final Object element) {
        if (isEnabled(element)) {
            if (isChecked(element))
                return imageCheckedEnabled;
            return imageUncheckedEnabled;
        } else {
            if (isChecked(element))
                return imageCheckedDisabled;
            return imageUncheckedDisabled;
        }
    }

    /**
     * @param element
     *            element to provide label for.
     * @return true if checkbox label should be checked for this element, false
     *         otherwise.
     */
    protected abstract boolean isChecked(Object element);

    /**
     * Default implementation always return true.
     *
     * @param element
     *            element to provide label for.
     * @return true if checkbox label should be enabled for this element, false
     *         otherwise.
     */
    protected boolean isEnabled(final Object element) {
        return true;
    }
}