Nattable Combination (Multiple Images) Image Painter

CombinationImagePainter.java

import java.util.ArrayList;
import java.util.List;

import org.eclipse.nebula.widgets.nattable.config.IConfigRegistry;
import org.eclipse.nebula.widgets.nattable.layer.cell.ILayerCell;
import org.eclipse.nebula.widgets.nattable.painter.cell.BackgroundPainter;
import org.eclipse.nebula.widgets.nattable.style.CellStyleUtil;
import org.eclipse.nebula.widgets.nattable.style.IStyle;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Rectangle;

/**
 * Paints the one or more images in a given cell based on the labels. Since label check happens only after this painter
 * has been invoked, it is required that this painter be registered with a always on label. Then this paint will decide
 * which image to paint based on other configured labels.
 *
 * Below is an example of this usage.
 *
 * <pre>
 * CombinationImagePainter painter = new CombinationImagePainter(4, true);
 *
 * //Replace ... below with appropriate images
 * painter.add("CREATE", ...);
 * painter.add("NO_CREATE", ...);
 * painter.add("READ", ...);
 * painter.add("NO_READ", ...);
 * painter.add("UPDATE", ...);
 * painter.add("NO_UPDATE", ...);
 * painter.add("DELETE", ...);
 * painter.add("NO_DELETE", ...);
 *
 * // Here COMBINATION_PAINTER is label that needs to be added by data provider whenever this painter needs to be invoked
 * configRegistry.registerConfigAttribute(CellConfigAttributes.CELL_PAINTER, painter, DisplayMode.NORMAL, "COMBINATION_PAINTER");
 * </pre>
 */
public class CombinationImagePainter extends BackgroundPainter {

    private List<LabelImagePair> labelImages = new ArrayList<>();
    private final boolean paintBg;
    private int spacing;

    /**
     * Creates a combination painter
     *
     * @param spacing number of pixels of spacing between each image. It can be -ve, in that case images will overlap
     * @param paintBg paint the background or not
     */
    public CombinationImagePainter(int spacing, boolean paintBg) {
        this.spacing = spacing;
        this.paintBg = paintBg;
    }

    /**
     * Adds a given label and image combination
     */
    public CombinationImagePainter add(String label, Image image) {
        labelImages.add(new LabelImagePair(label, image));
        return this;
    }

    @Override
    public int getPreferredWidth(ILayerCell cell, GC gc, IConfigRegistry configRegistry) {
        int width = 0;
        for (Image image : getImages(cell)) {
            if (width != 0) {
                width += spacing;
            }
            width += image.getBounds().width;
        }

        return width;
    }

    protected List<Image> getImages(ILayerCell cell) {
        List<Image> images = new ArrayList<>();
        for (LabelImagePair labelImage : labelImages) {
            if (cell.getConfigLabels().hasLabel(labelImage.label)) {
                images.add(labelImage.image);
            }
        }

        return images;
    }

    @Override
    public int getPreferredHeight(ILayerCell cell, GC gc, IConfigRegistry configRegistry) {
        int height = 0;
        for (Image image : getImages(cell)) {
            height = Math.max(height, image.getBounds().height);
        }

        return height;
    }

    @Override
    public void paintCell(ILayerCell cell, GC gc, Rectangle bounds, IConfigRegistry configRegistry) {
        if (this.paintBg) {
            super.paintCell(cell, gc, bounds, configRegistry);
        }

        IStyle cellStyle = CellStyleUtil.getCellStyle(cell, configRegistry);

        List<Image> images = getImages(cell);
        int boundX = bounds.x + CellStyleUtil.getHorizontalAlignmentPadding(cellStyle, bounds, getPreferredWidth(cell, gc, configRegistry));
        int paddingY = CellStyleUtil.getVerticalAlignmentPadding(cellStyle, bounds, getPreferredHeight(cell, gc, configRegistry));

        for (Image image : images) {
            Rectangle imageBounds = image.getBounds();
            gc.drawImage(image, boundX, bounds.y + paddingY);
            boundX += imageBounds.width + spacing;
        }

    }
}

class LabelImagePair {
    public final String label;
    public final Image image;

    public LabelImagePair(String label, Image image) {
        this.label = label;
        this.image = image;
    }
}