ZoomFocusFinder.java

package glug.gui.zoom;

import glug.gui.UITimeScale;
import glug.gui.timelinecursor.TimelineCursor;
import glug.model.time.LogInstant;

import javax.swing.JViewport;

import org.joda.time.Instant;
import org.joda.time.Interval;

public class ZoomFocusFinder {
	
	private final JViewport viewport;
	private final UITimeScale uiTimeScale;
	private final TimelineCursor timelineCursor;

	public ZoomFocusFinder(TimelineCursor timelineCursor, JViewport viewport, UITimeScale uiTimeScale) {
		this.timelineCursor = timelineCursor;
		this.viewport = viewport;
		this.uiTimeScale = uiTimeScale;
	}
	
	public Instant instantToZoomAround() {
		Instant instantToZoomAround = null;
		Interval visibleInterval = uiTimeScale.viewToModel(viewport.getViewRect());
		LogInstant dot = timelineCursor.getDot();
		if (dot != null && visibleInterval.contains(dot.getRecordedInstant())) {
			instantToZoomAround = dot.getRecordedInstant();
		}
		if (instantToZoomAround == null) {
			instantToZoomAround = new Instant(visibleInterval.getStartMillis()
					+ visibleInterval.toDurationMillis() / 2);
		}
		return instantToZoomAround;
	}
}