gistfile1.java

import com.google.gwt.cell.client.AbstractCell;
import com.google.gwt.cell.client.ValueUpdater;
import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.safehtml.client.SafeHtmlTemplates;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.safehtml.shared.SafeUri;

import java.util.HashSet;
import java.util.Set;

/**
 * This class creates a cell with a one clickable image inside.
 * The class is abstract thus it should implement event handler for the image.
 * Generic type supposed to be a same type of the model that is used in e.g. grid, 
 * so the value argument in render method would be the whole model of selected grid's row.
 * Created by Paniov on 02.03.2015.
 */
public abstract class ClickableIconCell<T> extends AbstractCell<T> {

    private ImageResource image;
    private Template template;
    private T model;

    private static final Template DEFAULT_TEMPLATE = GWT.create(Template.class);

    interface Template extends SafeHtmlTemplates {
        @SafeHtmlTemplates.Template("<img src='{0}' border='0' width='{1}' height='{2}' style='cursor:pointer;'>")
        SafeHtml draw(SafeUri imageUri, int width, int height);
    }

    public ClickableIconCell(ImageResource imageResource, Template template) {
        this.image = imageResource;
        this.template = template;
    }

    public ClickableIconCell(ImageResource imageResource) {
        this.image = imageResource;
        this.template = DEFAULT_TEMPLATE;
    }

    @Override
    public void render(Context context, T value, SafeHtmlBuilder sb) {
        if (value != null) {
            SafeHtml sh = template.draw(image.getSafeUri(), image.getWidth(), image.getHeight());
            sb.appendHtmlConstant(sh.asString());
        }
    }

    @Override
    public Set<String> getConsumedEvents() {
        Set<String> events = new HashSet<String>();
        events.add("click");
        return events;
    }

    @Override
    public void onBrowserEvent(Context context, Element parent, T value, NativeEvent event, ValueUpdater<T> valueUpdater) {
        super.onBrowserEvent(context, parent, value, event, valueUpdater);
        this.model = value;
        if (parent.getFirstChildElement().isOrHasChild(Element.as(event.getEventTarget()))) {
            handleEvent();
        }
    }

    public abstract void handleEvent();

    public T getModel() {
        return model;
    }

}