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>
@@ -33,6 +35,11 @@ public class EnhancedImage {
 	 * The orientation
 	 */
 	private Orientation orientation = Orientation.UNDEFINED;
+	
+	/**
+	 * The cached image (once downloaded)
+	 */
+	private Image cachedImage;
 
 	/**
 	 * Build an enhanced image from a url.
@@ -128,6 +135,14 @@ public class EnhancedImage {
 	public void setOrientation(Orientation orientation) {
 		this.orientation = orientation;
 	}
+	
+	public Image getCachedImage() {
+		return cachedImage;
+	}
+
+	public void setCachedImage(Image cachedImage) {
+		this.cachedImage = cachedImage;
+	}
 
 	@Override
 	public String toString() {

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

@@ -245,7 +245,7 @@ public class Carousel extends Composite{
 		currentPreviewPosition = 
 				currentPreviewPosition == listOfAttachmentsToShow.size() -1 ? 
 						0 : currentPreviewPosition + 1;
-		
+
 		// show the image
 		showImage(currentPreviewPosition);
 
@@ -332,40 +332,54 @@ public class Carousel extends Composite{
 		showLoader();
 
 		final EnhancedImage imageToShow = listOfAttachmentsToShow.get(index);
-		final String url = imageToShow.getImageUrl();
 
-		// when image is downloaded ...
+		// check if it was already shown before and cached...
-		shownImage.addLoadHandler(new LoadHandler() {
+		if(imageToShow.getCachedImage() != null){
 
-			@Override
+			shownImage = imageToShow.getCachedImage();
-			public void onLoad(LoadEvent event) {
+			setOrientation(imageToShow, imageToShow.getOrientation());
 
-				// call only if undefined
+		}else{
-				if(imageToShow.getOrientation().equals(Orientation.UNDEFINED)){
 
-					imageServices.getImageOrientation(url, new AsyncCallback<Orientation>() {
+			final String url = imageToShow.getImageUrl();
 
-						@Override
+			// when image is downloaded ...
-						public void onSuccess(Orientation result) {		
+			shownImage.addLoadHandler(new LoadHandler() {
-							imageToShow.setOrientation(result);
-							setOrientation(imageToShow, result);
-						}
 
-						@Override
+				@Override
-						public void onFailure(Throwable caught) {
+				public void onLoad(LoadEvent event) {
-							imageToShow.setOrientation(Orientation.DO_NOT_ROTATE);
-							setOrientation(imageToShow, Orientation.DO_NOT_ROTATE);
-						}
-					});
 
-				}else{
+					// call only if undefined
-					setOrientation(imageToShow, imageToShow.getOrientation());
+					if(imageToShow.getOrientation().equals(Orientation.UNDEFINED)){
+
+						imageServices.getImageOrientation(url, new AsyncCallback<Orientation>() {
+
+							@Override
+							public void onSuccess(Orientation result) {		
+								imageToShow.setOrientation(result);
+								setOrientation(imageToShow, result);
+							}
+
+							@Override
+							public void onFailure(Throwable caught) {
+								imageToShow.setOrientation(Orientation.DO_NOT_ROTATE);
+								setOrientation(imageToShow, Orientation.DO_NOT_ROTATE);
+							}
+						});
+
+					}else{
+						setOrientation(imageToShow, imageToShow.getOrientation());
+					}
+					
+					// cache it
+					imageToShow.setCachedImage(shownImage);
 				}
-			}
+			});
-		});
 
-		// fetch the image from the url
+			// fetch the image from the url
-		shownImage.setUrl(url);
+			shownImage.setUrl(url);
+
+		}
 
 		// change image tooltip
 		shownImage.setTitle(imageToShow.getToolTipToShow());
@@ -427,10 +441,10 @@ public class Carousel extends Composite{
 
 		default: shownImage.addStyleName("rotate-0");
 		}
-		
+
 		// few ms are needed to remove/add the style, after that we remove the loading image
 		Timer t = new Timer() {
-			
+
 			@Override
 			public void run() {
 				removeLoader();