VEventTimelineBand.java

/*
@VaadinAddonLicenseForJavaFiles@
 */
package com.spaceapplications.vaadin.addon.eventtimeline.gwt.client;

import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.event.dom.client.MouseDownEvent;
import com.google.gwt.event.dom.client.MouseDownHandler;
import com.google.gwt.event.dom.client.MouseMoveEvent;
import com.google.gwt.event.dom.client.MouseMoveHandler;
import com.google.gwt.event.dom.client.MouseUpEvent;
import com.google.gwt.event.dom.client.MouseUpHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Event.NativePreviewEvent;
import com.google.gwt.user.client.Event.NativePreviewHandler;
import com.google.gwt.user.client.ui.Widget;

/**
 * VEventTimelineBand.
 * 
 * @author Thomas Neidhart / Space Applications Services NV/SA
 */
public class VEventTimelineBand extends Widget implements MouseDownHandler,
		MouseMoveHandler, MouseUpHandler, NativePreviewHandler {

	private static final String CLASSNAME_BAND = VEventTimelineWidget.CLASSNAME	+ "-band";
	private static final String CLASSNAME_BAND_SELECTED = CLASSNAME_BAND + "-selected";
	private static final String CLASSNAME_BAND_LABEL = CLASSNAME_BAND	+ "-label";
	private static final String CLASSNAME_BAND_ADJUSTER = "v-band-adjuster";

	private final Element bandRoot;

	private final Element bandLabel;
	private final Element bandAdjuster;

	private boolean mouseDown;
	private boolean mouseIsActive = false;

	private boolean sizeAdjust;

	private int dragStartY;

	private HandlerRegistration mouseMoveReg, mouseUpReg, mouseDownReg,	preview;

	private int bandId;
	private VEventTimelineBandArea bandArea;
	private boolean selected;

	/**
	 * Create a new band.
	 * 
	 * @param bandId the band id
	 * @param caption the caption
	 * @param bandArea the ui element representing the band
	 */
	public VEventTimelineBand(int bandId, final String caption,	final VEventTimelineBandArea bandArea) {
		this.bandId = bandId;
		this.bandArea = bandArea;

		bandRoot = DOM.createDiv();
		setElement(bandRoot);

		setStyleName(CLASSNAME_BAND);

		bandLabel = DOM.createDiv();
		bandLabel.setClassName(CLASSNAME_BAND_LABEL);
		bandLabel.setInnerText(caption);
		bandRoot.appendChild(bandLabel);

		bandAdjuster = DOM.createDiv();
		bandAdjuster.setClassName(CLASSNAME_BAND_ADJUSTER);
		bandRoot.appendChild(bandAdjuster);
	}

	@Override
	protected void onLoad() {
		super.onLoad();
		mouseDownReg = addDomHandler(this, MouseDownEvent.getType());
		mouseUpReg = addDomHandler(this, MouseUpEvent.getType());
		mouseMoveReg = addDomHandler(this, MouseMoveEvent.getType());
		preview = Event.addNativePreviewHandler(this);

		disableAdjuster();
	}

	@Override
	protected void onUnload() {
		super.onUnload();
		if (mouseDownReg != null) {
			mouseDownReg.removeHandler();
			mouseDownReg = null;
		}
		if (mouseUpReg != null) {
			mouseUpReg.removeHandler();
			mouseUpReg = null;
		}
		if (mouseMoveReg != null) {
			mouseMoveReg.removeHandler();
			mouseMoveReg = null;
		}
		if (preview != null) {
			preview.removeHandler();
			preview = null;
		}
	}

	@Override
	public void setWidth(String width) {
		super.setWidth(width);
		updateBandAdjuster();
	}

	@Override
	public void setHeight(String height) {
		super.setHeight(height);
		updateBandAdjuster();
	}

	public int getHeight() {
		return DOM.getIntStyleAttribute(bandRoot, "height");
	}

	/**
	 * Returns true, if the band is selected.
	 * 
	 * @return
	 */
	public boolean isSelected() {
		return selected;
	}

	/**
	 * Pass true, to mark the band as selected and false to deselect a band.
	 * 
	 * @param value
	 */
	public void setSelected(boolean selected) {
		this.selected = selected;
		applySelectionStyle();
	}

	/**
	 * Applies a style attribute based on the selection state.
	 */
	private void applySelectionStyle() {
		if (selected) {
			removeStyleName(CLASSNAME_BAND);
			addStyleName(CLASSNAME_BAND_SELECTED);
		} else {
			removeStyleName(CLASSNAME_BAND_SELECTED);
			addStyleName(CLASSNAME_BAND);
		}
	}

	/**
	 * Returns the id of that band.
	 * 
	 * @return the bandId
	 */
	public int getId() {
		return bandId;
	}

	public void updateBandAdjuster() {
		int center = bandRoot.getOffsetWidth() / 2 - 8;
		DOM.setStyleAttribute(bandAdjuster, "left", center + "px");

		int bottom = bandRoot.getOffsetHeight() - bandLabel.getOffsetHeight() - 4;
		DOM.setStyleAttribute(bandAdjuster, "top", bottom + "px");
	}

	public void enableAdjuster() {
		DOM.setStyleAttribute(bandAdjuster, "visibility", "visible");
	}

	public void disableAdjuster() {
		DOM.setStyleAttribute(bandAdjuster, "visibility", "hidden");
	}

	public boolean isMouseOverSizeAdjuster(Event mouseEvent) {
		Element mouseOver = (Element) Element.as(mouseEvent.getEventTarget());
		return mouseOver == bandAdjuster;
	}

	/**
	 * Checks if element exists in the browser
	 * 
	 * @param elem
	 *            The element
	 * @return True if the element exists, else false
	 */
	public boolean hasElement(com.google.gwt.dom.client.Element elem) {
		if (elem == getElement() || elem == bandRoot || elem == bandLabel
				|| elem == bandAdjuster) {
			return true;
		} else {
			return false;
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.google.gwt.event.dom.client.MouseUpHandler#onMouseUp(com.google.gwt
	 * .event.dom.client.MouseUpEvent)
	 */
	public void onMouseUp(MouseUpEvent event) {
		mouseIsActive = false;

		DOM.releaseCapture(bandRoot);
		sizeAdjust = false;

		// notify that the band was selected
		bandArea.bandSelected(bandId);

		// redraw
		bandArea.redraw();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.google.gwt.event.dom.client.MouseMoveHandler#onMouseMove(com.google
	 * .gwt.event.dom.client.MouseMoveEvent)
	 */
	public void onMouseMove(MouseMoveEvent event) {
		NativeEvent mouseEvent = event.getNativeEvent();

		if (mouseDown) {
			int adjustment = mouseEvent.getClientY() - dragStartY;
			if (sizeAdjust) {
				if (bandArea.requestResize(bandId, getHeight(), adjustment)) {
					dragStartY = mouseEvent.getClientY();
				}
			}
		}
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.google.gwt.event.dom.client.MouseDownHandler#onMouseDown(com.google
	 * .gwt.event.dom.client.MouseDownEvent)
	 */
	public void onMouseDown(MouseDownEvent event) {
		mouseIsActive = true;

		NativeEvent mouseEvent = event.getNativeEvent();
		event.preventDefault();
		event.stopPropagation();

		DOM.setCapture(bandRoot);

		if (isMouseOverSizeAdjuster((Event) mouseEvent)) {
			sizeAdjust = true;
			dragStartY = mouseEvent.getClientY();
		}
	}

	public void onPreviewNativeEvent(NativePreviewEvent event) {
		// Monitor mouse button state
		if (event.getTypeInt() == Event.ONMOUSEUP
				&& event.getNativeEvent().getButton() == NativeEvent.BUTTON_LEFT) {
			mouseDown = false;
			if (mouseIsActive) {
				onMouseUp(null);
			}
		} else if (event.getTypeInt() == Event.ONMOUSEDOWN
				&& event.getNativeEvent().getButton() == NativeEvent.BUTTON_LEFT) {
			mouseDown = true;
		}
	}
}