added chached image, to avoid multiple download of the same image

git-svn-id: http://svn.research-infrastructures.eu/public/d4science/gcube/trunk/portlets/widgets/image-previewer-widget@134913 82a268e6-3cf1-43bd-a215-b396298e98cf

src/main/java/org/gcube/portlets/widgets/imagepreviewerwidget/client/EnhancedImage.java

@@ -2,6 +2,8 @@ package org.gcube.portlets.widgets.imagepreviewerwidget.client;
 
 import org.gcube.portlets.widgets.imagepreviewerwidget.shared.Orientation;
 
+import com.github.gwtbootstrap.client.ui.Image;
+
 /**
  * This class allows to build the image to show within the carousel. It contains:
  * <ul>
@@ -34,6 +36,11 @@ public class EnhancedImage {
 	 */
 	private Orientation orientation = Orientation.UNDEFINED;
 	
+	/**
+	 * The cached image (once downloaded)
+	 */
+	private Image cachedImage;
+
 	/**
 	 * Build an enhanced image from a url.
 	 * @param imageUrl the url of the image.
@@ -129,6 +136,14 @@ public class EnhancedImage {
 		this.orientation = orientation;
 	}
 	
+	public Image getCachedImage() {
+		return cachedImage;
+	}
+
+	public void setCachedImage(Image cachedImage) {
+		this.cachedImage = cachedImage;
+	}
+
 	@Override
 	public String toString() {
 		return "EnhancedImage [titleToShow=" + titleToShow + ", toolTipToShow="

src/main/java/org/gcube/portlets/widgets/imagepreviewerwidget/client/ui/Carousel.java

@@ -332,6 +332,15 @@ public class Carousel extends Composite{
 		showLoader();
 
 		final EnhancedImage imageToShow = listOfAttachmentsToShow.get(index);
+
+		// check if it was already shown before and cached...
+		if(imageToShow.getCachedImage() != null){
+
+			shownImage = imageToShow.getCachedImage();
+			setOrientation(imageToShow, imageToShow.getOrientation());
+
+		}else{
+
 			final String url = imageToShow.getImageUrl();
 
 			// when image is downloaded ...
@@ -361,12 +370,17 @@ public class Carousel extends Composite{
 					}else{
 						setOrientation(imageToShow, imageToShow.getOrientation());
 					}
+					
+					// cache it
+					imageToShow.setCachedImage(shownImage);
 				}
 			});
 
 			// fetch the image from the url
 			shownImage.setUrl(url);
 
+		}
+
 		// change image tooltip
 		shownImage.setTitle(imageToShow.getToolTipToShow());