Question

I have a MyComposite class, where I want to animate the Size change.
For that I am changing the size in a loop.

After each loopteration I call layout().

Unfortunately the Composite doesnÄt repaint after each iteration, but jumps directly to the final size of my Composite.

How can I force the Widget to redraw on every size change?

MyComposite and Animation:

//start
new Animation().start(myComposite);

...

public MyComposite(Composite parent, int style, int bgcolor) {
        super(parent, style);
        this.setBackground(getDisplay().getSystemColor(bgcolor));       
    }

    @Override
    public Point computeSize(int wHint, int hHint, boolean changed) {
        return super.computeSize(width, height, changed);
    }


    class Animation{
        public void start(MyComposite composite){
            for(int i=0; i<1000; i++){
                composite.width++;
                composite.getParent().layout(true, true);
            }
        }
    }

MyComposite:

Answer 1

The redrawing works as following:

• layout() marks forces the repositioning of all composite-children. This will become visible on next repaint, which will be done somewhere in the future, when composite’s screen-area will be redrawn
• redraw() marks the widget an invalidated. On next redraw-system-action this area will be repainted.
• update() forces all outstanding redraw() requests to be completed NOW.

So the problem was, that I did not trigger the repaint request to be done IMMEDIATELY.
The correct animation function looks like:

//layout of the composite doesn't work
//composite.layout(true, true);

//layout of parent works
composite.getParent().layout(true, true);

//marks the composite's screen are as invalidates, which will force a 
composite.redraw(); redraw on next paint request 

//tells the application to do all outstanding paint requests immediately
composite.update();