Add QueueSizeListener to ImageManager and show number of queued images in status bar

src/uk/co/md87/evetool/ImageManager.java

@@ -23,10 +23,19 @@
 package uk.co.md87.evetool;
 
 import java.awt.Image;
+import java.io.File;
 import java.io.IOException;
 import java.net.URL;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
 import javax.imageio.ImageIO;
 
+import uk.co.md87.evetool.api.io.QueueSizeListener;
+
 /**
  *
  * TODO: Document ImageManager
@@ -34,16 +43,67 @@ import javax.imageio.ImageIO;
  */
 public class ImageManager {
 
+    protected static final List<String> REQUESTS = new ArrayList<String>();
+
+    private static final List<QueueSizeListener> listeners = new ArrayList<QueueSizeListener>();
+
+    private static final AtomicInteger queueSize = new AtomicInteger(0);
+
     protected final String cacheDir;
 
     public ImageManager(final String cacheDir) {
         this.cacheDir = cacheDir;
+
+        final File dir = new File(cacheDir);
+        if (!dir.isDirectory() && !dir.mkdirs()) {
+            Logger.getLogger(ImageManager.class.getName()).log(Level.SEVERE,
+                    "Unable to create image cache directory");
+        }
     }
 
     public Image getImage(final ImageType type, final Object ... arguments) throws IOException {
         final String url = type.getUrl(arguments);
-        return ImageIO.read(new URL(url));
+
+        synchronized (REQUESTS) {
+            fireQueueSizeChange(queueSize.incrementAndGet());
+
+            while (REQUESTS.contains(url)) {
+                try {
+                    REQUESTS.wait();
+                } catch (InterruptedException ex) {
+                    // Ignore
+                }
+            }
+
+            REQUESTS.add(url);
+        }
+
+        try {
+            final Image res = ImageIO.read(new URL(url));
+            return res;
+        } finally {
+            synchronized (REQUESTS) {
+                fireQueueSizeChange(queueSize.decrementAndGet());
+                
+                REQUESTS.remove(url);
+                REQUESTS.notifyAll();
+            }
+        }
     }
 
+    public static void addQueueSizeListener(final QueueSizeListener listener) {
+        synchronized (listeners) {
+            listeners.add(listener);
+            listener.queueSizeUpdate(queueSize.get());
+        }
+    }
+
+    protected static void fireQueueSizeChange(final int queueSize) {
+        synchronized (listeners) {
+            for (QueueSizeListener listener : listeners) {
+                listener.queueSizeUpdate(queueSize);
+            }
+        }
+    }
     
 }

src/uk/co/md87/evetool/ui/StatusPanel.java

@@ -30,6 +30,7 @@ import javax.swing.JPanel;
 
 import net.miginfocom.swing.MigLayout;
 
+import uk.co.md87.evetool.ImageManager;
 import uk.co.md87.evetool.Main;
 import uk.co.md87.evetool.api.io.ApiDownloader;
 import uk.co.md87.evetool.api.io.QueueSizeListener;
@@ -39,7 +40,7 @@ import uk.co.md87.evetool.api.io.QueueSizeListener;
  * 
  * @author chris
  */
-public class StatusPanel extends JPanel implements QueueSizeListener {
+public class StatusPanel extends JPanel {
 
     /**
      * A version number for this class. It should be changed whenever the class
@@ -51,6 +52,8 @@ public class StatusPanel extends JPanel implements QueueSizeListener {
     /** Labels used to display various pieces of information. */
     private final JLabel leftLabel, centreLabel, rightLabel;
 
+    private int apiSize = 0, imageSize = 0;
+
     /**
      * Creates a new status panel for the specified window.
      *
@@ -69,14 +72,36 @@ public class StatusPanel extends JPanel implements QueueSizeListener {
         add(centreLabel, "push, grow");
         add(rightLabel, "push, grow");
 
-        ApiDownloader.addQueueSizeListener(this);
+        ApiDownloader.addQueueSizeListener(new QueueSizeListener() {
+            /** {@inheritDoc} */
+            @Override
+            public void queueSizeUpdate(final int size) {
+                apiSize = size;
+                updateLabel();
+            }
+        });
+
+        ImageManager.addQueueSizeListener(new QueueSizeListener() {
+            /** {@inheritDoc} */
+            @Override
+            public void queueSizeUpdate(final int size) {
+                imageSize = size;
+                updateLabel();
+            }
+        });
     }
 
-    /** {@inheritDoc} */
-    @Override
-    public void queueSizeUpdate(final int size) {
-        centreLabel.setText(size == 0 ? "" : 
-            (size + " API quer" + (size == 1 ? "y" : "ies") + " pending"));
+    /**
+     * Updates the centre label to reflect the number of API and image requests
+     * pending.
+     */
+    protected void updateLabel() {
+        centreLabel.setText((apiSize == 0 ? "" :
+                (apiSize + " API quer" + (apiSize == 1 ? "y" : "ies")))
+                + (imageSize * apiSize > 0 ? " and " : "")
+                + (imageSize == 0 ? "" : (imageSize + " image request"
+                + (imageSize == 1 ? "" : "s")))
+                + (imageSize + apiSize > 0 ? " pending" : ""));
     }
 
 }