image-previewer-widget/src/main/java/org/gcube/portlets/widgets/imagepreviewerwidget/client/ui/Carousel.java

package org.gcube.portlets.widgets.imagepreviewerwidget.client.ui;

import java.util.List;

import org.gcube.portlets.widgets.imagepreviewerwidget.client.EnhancedImage;

import com.github.gwtbootstrap.client.ui.Button;
import com.github.gwtbootstrap.client.ui.Image;
import com.github.gwtbootstrap.client.ui.Modal;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.uibinder.client.UiField;
import com.google.gwt.uibinder.client.UiHandler;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.Widget;

/**
 * A carousel for image/file previews.
 * @author Costantino Perciante at ISTI-CNR
 */
public class Carousel extends Composite{

	private static CarouselUiBinder uiBinder = GWT
			.create(CarouselUiBinder.class);

	interface CarouselUiBinder extends UiBinder<Widget, Carousel> {
	}

	@UiField
	Modal mainModalPanel;

	@UiField
	Button showButton;

	@UiField
	Button prevButton;

	@UiField
	Button nextButton;

	@UiField
	Button downloadButton;

	@UiField
	Button closeButton;

	@UiField
	Image shownImage;

	@UiField
	HorizontalPanel horizontaFooterPanel;

	private List<EnhancedImage> listOfAttachmentsToShow;

	private int currentPreviewPosition;

	/**
	 * Build a carousel that shows imagesToShow images.
	 * @param imagesToShow
	 */
	public Carousel(List<EnhancedImage> imagesToShow) {

		initWidget(uiBinder.createAndBindUi(this));
		
		// hide show button (not needed when the widget is used)
		showButton.setVisible(false);

		// set alignment of the horizontal panel's children
		horizontaFooterPanel.setCellHorizontalAlignment(closeButton, HorizontalPanel.ALIGN_CENTER);
		horizontaFooterPanel.setCellHorizontalAlignment(downloadButton, HorizontalPanel.ALIGN_CENTER);
		horizontaFooterPanel.setCellHorizontalAlignment(prevButton, HorizontalPanel.ALIGN_LEFT);
		horizontaFooterPanel.setCellHorizontalAlignment(nextButton, HorizontalPanel.ALIGN_RIGHT);

		// set central buttons' cell widths to be equal
		horizontaFooterPanel.setCellWidth(downloadButton, "200px");
		horizontaFooterPanel.setCellWidth(closeButton, "200px");

		// set vertical alignment
		horizontaFooterPanel.setCellVerticalAlignment((Widget)nextButton, VerticalPanel.ALIGN_MIDDLE);
		horizontaFooterPanel.setCellVerticalAlignment(prevButton,  VerticalPanel.ALIGN_MIDDLE);

		// prev button
		prevButton.setText("<<");

		// next button
		nextButton.setText(">>");

		// save the attachments list
		listOfAttachmentsToShow = imagesToShow;

		// take the first object
		currentPreviewPosition = 0;

		// show it
		shownImage.setUrl(listOfAttachmentsToShow.get(currentPreviewPosition).getImageUrl());

		// change image tooltip
		shownImage.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getToolTipToShow());

		// change the title to the modal
		mainModalPanel.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getTitleToShow());

	}

	@UiHandler("showButton")
	public void onClick(ClickEvent e){

		mainModalPanel.show();

	}
	
	/**
	 * Used to show this carousel.
	 */
	public void show(){
		
		mainModalPanel.show();
	}

	@UiHandler("closeButton")
	public void closeOnClick(ClickEvent e){

		mainModalPanel.hide();

	}

	@UiHandler("downloadButton")
	public void downloadOnClick(ClickEvent e){

		Window.open(listOfAttachmentsToShow.get(currentPreviewPosition).getDownloadUrl(), "_blank", "");

	}

	@UiHandler("prevButton")
	public void onClickPrev(ClickEvent e){

		int prevPreviewPosition = currentPreviewPosition == 0 ? listOfAttachmentsToShow.size() - 1 : currentPreviewPosition - 1;
		currentPreviewPosition = prevPreviewPosition;

		// show it
		shownImage.setUrl(listOfAttachmentsToShow.get(currentPreviewPosition).getImageUrl());

		// change image tooltip
		shownImage.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getToolTipToShow());

		// change the title to the modal
		mainModalPanel.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getTitleToShow());

	}

	@UiHandler("nextButton")
	public void onClickNext(ClickEvent e){

		int nextPreviewPosition = currentPreviewPosition == listOfAttachmentsToShow.size() -1 ? 
				0 : currentPreviewPosition + 1;
		currentPreviewPosition = nextPreviewPosition;

		// show it
		shownImage.setUrl(listOfAttachmentsToShow.get(currentPreviewPosition).getImageUrl());

		// change image tooltip
		shownImage.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getToolTipToShow());

		// change the title to the modal
		mainModalPanel.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getTitleToShow());

	}

	/**
	 * Change the current image.
	 * @param newPosition index of the new image to show
	 */
	public void changeIndexImageShown(int newPosition){

		if(newPosition < 0 || newPosition >= listOfAttachmentsToShow.size())
			return;

		currentPreviewPosition = newPosition;

		// show it
		shownImage.setUrl(listOfAttachmentsToShow.get(currentPreviewPosition).getImageUrl());

		// change image tooltip
		shownImage.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getToolTipToShow());

		// change the title to the modal
		mainModalPanel.setTitle(listOfAttachmentsToShow.get(currentPreviewPosition).getTitleToShow());

	}

}