Blinking background rows of TableViewer or TreeViewer in SWT

Question

I need the ability to have a blinking (red, maybe more colors) background for rows in a TableViewer/TreeViewer. What are the best options?

There may be more than one row blinking, the blinking MUST be synchron and I need two blinking modes, fast and slow.

Answer 1

I would do something similar to this. Update the elements that you need to change the colors for at a regular interval. At each update toggle the colors depending on how you want them to flash.

void scheduleColorChange(final Color colors[], final int startIndex, final int changeInterval)
{
  getDisplay().timerExec(changeInterval, new Runnable()
  {
    public void run()
    {
      Object[] elements = getColorChangingElements();
      setColorsForFlashingElements(elements, colors[index%colors.length]);
      getViewer().update(elements);
      scheduleColorChange(colors, startIndex+1, changeInterval)
    }
  });
}  

and the have you label provider implement IColorProvider.

Answer 2

Howdy, this is a fast hack that shows the idea, improvable in many ways. I show the three classes doing the job. If you want I can provide an exported source plugin ready to install into your eclipse workbench tomorrow. Here are the core classes:

import java.util.TimerTask;

import org.eclipse.jface.resource.ColorDescriptor;
import org.eclipse.jface.viewers.IColorProvider;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.LabelProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.ui.PlatformUI;

public class Blinker extends LabelProvider implements ITableLabelProvider, IColorProvider  {

    private final TableViewer viewer;


    public Blinker(TableViewer viewer){
        this.viewer = viewer;
    }

    // this is just a lousy way to store blink_on/blink_off...
    private byte state; 

    // there must be a better way to get a color...
    final static Color red = ColorDescriptor.createFrom(new RGB(255,0,0)).createColor(PlatformUI.getWorkbench().getDisplay());
    final static Color green = ColorDescriptor.createFrom(new RGB(0,255,0)).createColor(PlatformUI.getWorkbench().getDisplay());


    private final TimerTask task = new TimerTask(){
        @Override
        public void run() {
            state++;
            PlatformUI.getWorkbench().getDisplay().asyncExec(new Runnable(){
                public void run() {
                    viewer.refresh();
                }
            });
        }
    };

    private Timer t;

    synchronized byte getState(){
        return state;
    }

    @Override
    public Image getColumnImage(Object element, int columnIndex) {
        return null;
    }

    @Override
    public String getColumnText(Object element, int columnIndex) {
        return ((Element) element).text;
    }

    @Override
    public Color getBackground(Object object) {
        Element element = (Element) object;
        if (element.isBlinking()){
            return getState() % 2 == 0 ? Blinker.red : Blinker.green;
        } else {
            return Blinker.green;
        }
    }

    @Override
    public Color getForeground(Object element) {
        return null;
    }


    public void start() {
        t = new Timer();
        t.schedule(task, 200, 1000);
    }

    public void stop() {
        t.cancel();
        t = null;
        }

}

This is a sample model class. Blink state is stored within the object, but you might want to improve this by using some sort of Adapter:

package com.example.blinker;

public class Element {

    private boolean blinking;
    public final String text;


    public Element(String string, boolean b) {
        this.text = string;
        this.blinking = b;
    }


    public synchronized boolean isBlinking(){
        return blinking;
    }


    public synchronized void setBlinking(boolean b){
        this.blinking = b;
    }


    public static final Element[] sampledata = new Element[] {
        new Element("Merkur", false),
        new Element("Venus", true),
        new Element("Erde", false),
        new Element("Mars", true),
        new Element("Jupiter", false),
        new Element("Saturn", true),
        new Element("Uranus", false),
        new Element("Neptun", true),
        new Element("Pluto", false),
    };

}

And finally a TableViewer embedded in a View, making use of the two above:

package com.example.blinker.views;

import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.ui.part.ViewPart;

import com.example.blinker.Blinker;
import com.example.blinker.Element;

public class SampleView extends ViewPart {

    public static final String ID = "com.example.blinker.views.SampleView";

    private TableViewer viewer;
    private Blinker blinker;

    class ViewContentProvider implements IStructuredContentProvider {
        public void inputChanged(Viewer v, Object oldInput, Object newInput) {}
        public void dispose() {}
        public Object[] getElements(Object parent) {
            return Element.sampledata;
        }
    }

    public void createPartControl(Composite parent) {
        viewer = new TableViewer(parent, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL);
        viewer.setContentProvider(new ViewContentProvider());
        blinker = new Blinker(viewer);
        viewer.setLabelProvider(blinker);
        viewer.setInput(new Object());
        blinker.start();
    }

    public void setFocus() {
        viewer.getControl().setFocus();
    }

    public void dispose() {
        blinker.stop();
    }
}