/*--------------------------------------------------------------------------
    *  Copyright 2008 utgenome.org
    *
    *  Licensed under the Apache License, Version 2.0 (the "License");
    *  you may not use this file except in compliance with the License.
    *  You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *--------------------------------------------------------------------------*/
  //--------------------------------------
  // utgb-widget Project
  //
  // Icon.java
  // Since: Apr 24, 2008
  //
  // $URL$ 
  // $Author$
  //--------------------------------------
  package org.utgenome.gwt.widget.client;
  
  import com.google.gwt.dom.client.Document;
  import com.google.gwt.dom.client.NativeEvent;
  import com.google.gwt.event.dom.client.ClickHandler;
  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.ui.FocusPanel;
  import com.google.gwt.user.client.ui.Image;
  
  /**
   * Icon image which flips on mouse over events
   * 
   * @author leo
   * 
   */
  public class Icon extends FocusPanel {
  
  	private Element currentFace = null;
  	private Image iconImage;
  	private Image mouseOverIconImage;
  
  	//private ArrayList<ClickHandler> clickListenerList = new ArrayList<ClickHandler>();
  
  	// icon state
  	private boolean isFocusing = false;
  	private boolean isCapturing = false;
  	private boolean isHovering = false;
  
  	public Icon(Image iconImage, Image mouseOverIconImage) {
  		this.iconImage = iconImage;
  		this.mouseOverIconImage = mouseOverIconImage;
  
  		Style.cursor(this, Style.CURSOR_POINTER);
  
  		updateIconFace(iconImage.getElement());
  	}
  
  	public void setIcon(Icon newIcon) {
  		this.iconImage = newIcon.getIconImage();
  		this.mouseOverIconImage = newIcon.getMouseOverIconImage();
  
  		updateIconFace(iconImage.getElement());
  	}
  
  	public void setIconImage(Image newIconImage) {
  		this.iconImage = newIconImage;
  		this.mouseOverIconImage = newIconImage;
  
  		updateIconFace(iconImage.getElement());
  	}
  
  	private void updateIconFace(Element newFace) {
  		if (currentFace != newFace) {
  			if (currentFace != null)
  				DOM.removeChild(getElement(), currentFace);
  
  			currentFace = newFace;
  			DOM.appendChild(getElement(), currentFace);
  		}
  	}
  
  	public Image getIconImage() {
  		return iconImage;
  	}
  
  	public Image getMouseOverIconImage() {
  		return mouseOverIconImage;
  	}
  
  	public void addClickHanlder(ClickHandler listener) {
  		this.addClickHandler(listener);
  	}
  
 	private void setHovering(boolean hovering) {
 		this.isHovering = hovering;
 		updateIconFace(isHovering ? mouseOverIconImage.getElement() : iconImage.getElement());
 	}
 
 	/**
 	 * Called when the user finishes clicking on this button. The default behavior is to fire the click event to
 	 * listeners. Subclasses that override {@link #onClickStart()} should override this method to restore the normal
 	 * widget display.
 	 */
 	protected void onClick() {
 		NativeEvent e = Document.get().createClickEvent(1, 0, 0, 0, 0, false, false, false, false);
 
 	}
 
 	/**
 	 * Called when the user aborts a click in progress; for example, by dragging the mouse outside of the button before
 	 * releasing the mouse button. Subclasses that override {@link #onClickStart()} should override this method to
 	 * restore the normal widget display.
 	 */
 	protected void onClickCancel() {
 
 	}
 
 	/**
 	 * Called when the user begins to click on this button. Subclasses may override this method to display the start of
 	 * the click visually; such subclasses should also override {@link #onClick()} and {@link #onClickCancel()} to
 	 * restore normal visual state. Each <code>onClickStart</code> will eventually be followed by either
 	 * <code>onClick</code> or <code>onClickCancel</code>, depending on whether the click is completed.
 	 */
 	protected void onClickStart() {
 
 	}
 
 	@Override
 	public void onBrowserEvent(Event event) {
 		// Should not act on button if disabled.
 
 		int type = DOM.eventGetType(event);
 		switch (type) {
 		case Event.ONMOUSEDOWN:
 			isFocusing = true;
 			onClickStart();
 			// DOM.setCapture(getElement());
 			isCapturing = true;
 			// Prevent dragging (on some browsers);
 			DOM.eventPreventDefault(event);
 			break;
 		case Event.ONMOUSEUP:
 			if (isCapturing) {
 				isCapturing = false;
 				// DOM.releaseCapture(getElement());
 				if (isHovering) {
 					onClick();
 				}
 			}
 			break;
 		case Event.ONMOUSEMOVE:
 			if (isCapturing) {
 				// Prevent dragging (on other browsers);
 				DOM.eventPreventDefault(event);
 			}
 			break;
 		case Event.ONMOUSEOUT:
 			Element to = DOM.eventGetToElement(event);
 			if (DOM.isOrHasChild(getElement(), DOM.eventGetTarget(event)) && (to == null || !DOM.isOrHasChild(getElement(), to))) {
 				if (isCapturing) {
 					onClickCancel();
 					// DOM.releaseCapture(getElement());
 				}
 			}
 			setHovering(false);
 			break;
 		case Event.ONMOUSEOVER:
 			if (DOM.isOrHasChild(getElement(), DOM.eventGetTarget(event))) {
 				setHovering(true);
 				if (isCapturing) {
 					onClickStart();
 				}
 			}
 			break;
 		case Event.ONCLICK:
 			// we handle clicks ourselves
 			return;
 		case Event.ONBLUR:
 			if (isFocusing) {
 				isFocusing = false;
 				onClickCancel();
 			}
 			break;
 		case Event.ONLOSECAPTURE:
 			if (isCapturing) {
 				isCapturing = false;
 				onClickCancel();
 			}
 			break;
 		case Event.ONERROR:
 			setHovering(false);
 			break;
 		}
 
 		super.onBrowserEvent(event);
 
 		// Synthesize clicks based on keyboard events AFTER the normal key handling.
 		char keyCode = (char) DOM.eventGetKeyCode(event);
 		switch (type) {
 		case Event.ONKEYDOWN:
 			if (keyCode == ' ') {
 				isFocusing = true;
 				onClickStart();
 			}
 			break;
 		case Event.ONKEYUP:
 			if (isFocusing && keyCode == ' ') {
 				isFocusing = false;
 				onClick();
 			}
 			break;
 		case Event.ONKEYPRESS:
 			if (keyCode == '\n' || keyCode == '\r') {
 				onClickStart();
 				onClick();
 			}
 			break;
 		}
 	}
 
 }