fix #20799 - fix performance/memory issues while scrolling across many geolocated images

git-svn-id: https://josm.openstreetmap.de/svn/trunk@18150 0c6e7542-c601-0410-84e7-c038aed88b3b

Author: don-vip

src/org/openstreetmap/josm/gui/layer/geoimage/ImageDisplay.java

@@ -21,6 +21,7 @@
 import java.awt.image.BufferedImage;
 import java.io.IOException;
 import java.util.Objects;
+import java.util.concurrent.Future;
 
 import javax.swing.JComponent;
 import javax.swing.SwingUtilities;
@@ -634,13 +635,12 @@ public void destroy() {
     /**
      * Sets a new source image to be displayed by this {@code ImageDisplay}.
      * @param entry new source image
-     * @since 13220
+     * @return a {@link Future} representing pending completion of the image loading task
+     * @since 18150
      */
-    public void setImage(ImageEntry entry) {
+    public Future<?> setImage(ImageEntry entry) {
         LoadImageRunnable runnable = setImage0(entry);
-        if (runnable != null) {
-            MainApplication.worker.execute(runnable);
-        }
+        return runnable != null ? MainApplication.worker.submit(runnable) : null;
     }
 
     protected LoadImageRunnable setImage0(ImageEntry entry) {

src/org/openstreetmap/josm/gui/layer/geoimage/ImageViewerDialog.java

@@ -18,6 +18,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+import java.util.concurrent.Future;
 
 import javax.swing.AbstractAction;
 import javax.swing.Box;
@@ -72,6 +73,7 @@ public final class ImageViewerDialog extends ToggleDialog implements LayerChange
             () -> Collections.singleton(imageryFilterSettings));
 
     private final ImageDisplay imgDisplay = new ImageDisplay(imageryFilterSettings);
+    private Future<?> imgLoadingFuture;
     private boolean centerView;
 
     // Only one instance of that class is present at one time
@@ -204,6 +206,7 @@ public void destroy() {
         imageRemoveAction.destroy();
         imageRemoveFromDiskAction.destroy();
         imageZoomAction.destroy();
+        cancelLoadingImage();
         super.destroy();
         dialog = null;
     }
@@ -466,9 +469,10 @@ public void displayImages(ImageData data, List<ImageEntry> entries) {
             btnCopyPath.setEnabled(true);
 
             if (imageChanged) {
+                cancelLoadingImage();
                 // Set only if the image is new to preserve zoom and position if the same image is redisplayed
                 // (e.g. to update the OSD).
-                imgDisplay.setImage(entry);
+                imgLoadingFuture = imgDisplay.setImage(entry);
             }
             setTitle(tr("Geotagged Images") + (!entry.getDisplayName().isEmpty() ? " - " + entry.getDisplayName() : ""));
             StringBuilder osd = new StringBuilder(entry.getDisplayName());
@@ -627,6 +631,13 @@ private void showLayer(Layer newLayer) {
         }
     }
 
+    private void cancelLoadingImage() {
+        if (imgLoadingFuture != null) {
+            imgLoadingFuture.cancel(false);
+            imgLoadingFuture = null;
+        }
+    }
+
     @Override
     public void selectedImageChanged(ImageData data) {
         displayImages(data, data.getSelectedImages());

src/org/openstreetmap/josm/gui/progress/swing/ProgressMonitorExecutor.java

@@ -48,7 +48,7 @@ public void afterExecute(final Runnable r, Throwable t) {
             try {
                 ((Future<?>) r).get();
             } catch (CancellationException cancellationException) {
-                t = cancellationException;
+                Logging.debug("Thread {0} raised {1}", Thread.currentThread().getName(), cancellationException);
             } catch (ExecutionException executionException) {
                 Logging.trace(executionException);
                 t = executionException.getCause();