Use feed image if media file has no image

closes #484

src/de/danoeh/antennapod/asynctask/PicassoImageResource.java

@@ -18,8 +18,20 @@ public interface PicassoImageResource {
      */
     public static final String SCHEME_MEDIA = "media";
 
+
+    /**
+     * Parameter key for an encoded fallback Uri. This Uri MUST point to a local image file
+     */
+    public static final String PARAM_FALLBACK = "fallback";
+
     /**
      * Returns a Uri to the image or null if no image is available.
+     * <p/>
+     * The Uri can either be an HTTP-URL, a URL pointing to a local image file or
+     * a non-image file (see SCHEME_MEDIA for more details).
+     * <p/>
+     * The Uri can also have an optional fallback-URL if loading the default URL
+     * failed (see PARAM_FALLBACK).
      */
     public Uri getImageUri();
 }

src/de/danoeh/antennapod/asynctask/PicassoProvider.java

@@ -127,14 +127,22 @@ public class PicassoProvider {
                     mmr.setDataSource(uri.getPath());
                     byte[] data = mmr.getEmbeddedPicture();
                     mmr.release();
+
                     if (data != null) {
                         return new Response(new ByteArrayInputStream(data), true, data.length);
                     } else {
-                        return null;
+
+                        // check for fallback Uri
+                        String fallback = Uri.decode(Uri.parse(uri.getQueryParameter(PicassoImageResource.PARAM_FALLBACK)).getPath());
+                        if (fallback != null) {
+                            File imageFile = new File(fallback);
+                            return new Response(new BufferedInputStream(new FileInputStream(imageFile)), true, imageFile.length());
+                        } else {
+                            return null;
+                        }
                     }
                 }
             }
-
             return okHttpDownloader.load(uri, b);
         }
     }

src/de/danoeh/antennapod/feed/FeedMedia.java

@@ -386,9 +386,23 @@ public class FeedMedia extends FeedFile implements Playable {
 
     @Override
     public Uri getImageUri() {
+        final Uri feedImgUri = getFeedImageUri();
+
         if (localFileAvailable()) {
-            return new Uri.Builder().scheme(SCHEME_MEDIA).encodedPath(getLocalMediaUrl()).build();
-        } else if (item != null && item.getFeed() != null) {
+            Uri.Builder builder = new Uri.Builder();
+            builder.scheme(SCHEME_MEDIA)
+                    .encodedPath(getLocalMediaUrl());
+            if (feedImgUri != null) {
+                builder.appendQueryParameter(PARAM_FALLBACK, feedImgUri.toString());
+            }
+            return builder.build();
+        } else {
+            return feedImgUri;
+        }
+    }
+
+    private Uri getFeedImageUri() {
+        if (item != null && item.getFeed() != null) {
             return item.getFeed().getImageUri();
         } else {
             return null;