"Download" menu button on image detail page.

Saves original file into the SD card "Downloads" directory via
Android's DownloadManager service.

On Gingerbread the notification vanishes after downloda, but we
force the gallery to reindex the downloads area so you can still
manually bump over to Gallery.

On ICS/JB the notification hangs around and can be used to open
the saved file directly.

Note that on Gingerbread we have to download over HTTP because
DownloadManager didn't support HTTPS.

Included copy of stock 'upload' icon, flipped it for 'download'.

commons/res/menu/fragment_image_detail.xml

@@ -11,6 +11,11 @@
           android:icon="@android:drawable/ic_menu_view"
           android:title="@string/menu_open_in_browser"
             />
+    <item android:id="@+id/menu_download_current_image"
+          android:showAsAction="always"
+          android:icon="@drawable/ic_menu_download"
+          android:title="Download"
+          />
     <item android:id="@+id/menu_retry_current_image"
           android:showAsAction="always|withText"
           android:icon="@android:drawable/ic_menu_revert"

commons/src/main/java/org/wikimedia/commons/media/MediaDetailPagerFragment.java

@@ -1,6 +1,8 @@
 package org.wikimedia.commons.media;
 
+import android.app.DownloadManager;
 import android.content.*;
+import android.database.Cursor;
 import android.net.*;
 import android.os.*;
 import android.support.v4.app.Fragment;
@@ -132,6 +134,9 @@ public class MediaDetailPagerFragment extends SherlockFragment implements ViewPa
                 viewIntent.setData(Uri.parse(m.getDescriptionUrl()));
                 startActivity(viewIntent);
                 return true;
+            case R.id.menu_download_current_image:
+                downloadMedia(m);
+                return true;
             case R.id.menu_retry_current_image:
                 // Is this... sane? :)
                 ((ContributionsActivity)getSherlockActivity()).retryUpload(pager.getCurrentItem());
@@ -147,6 +152,71 @@ public class MediaDetailPagerFragment extends SherlockFragment implements ViewPa
         }
     }
 
+    /**
+     * Start the media file downloading to the local SD card/storage.
+     * The file can then be opened in Gallery or other apps.
+     *
+     * @param m
+     */
+    private void downloadMedia(Media m) {
+        String imageUrl = m.getImageUrl(),
+               fileName = m.getFilename();
+        // Strip 'File:' from beginning of filename, we really shouldn't store it
+        fileName = fileName.replaceFirst("^File:", "");
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
+            // Gingerbread DownloadManager has no HTTPS support...
+            // Download file over HTTP, there'll be no credentials
+            // sent so it should be safe-ish.
+            imageUrl = imageUrl.replaceFirst("^https://", "http://");
+        }
+        Uri imageUri = Uri.parse(imageUrl);
+
+        DownloadManager.Request req = new DownloadManager.Request(imageUri);
+        req.setDescription(m.getDisplayTitle());
+        req.setTitle("Commons");
+        req.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
+            // Modern Android updates the gallery automatically. Yay!
+            req.allowScanningByMediaScanner();
+
+            // On HC/ICS/JB we can leave the download notification up when complete.
+            // This allows folks to open the file directly in gallery viewer.
+            req.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
+        }
+
+        final DownloadManager manager = (DownloadManager)getSherlockActivity().getSystemService(Context.DOWNLOAD_SERVICE);
+        final long downloadId = manager.enqueue(req);
+
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
+            // For Gingerbread compatibility...
+            BroadcastReceiver onComplete = new BroadcastReceiver() {
+                @Override
+                public void onReceive(Context context, Intent intent) {
+                    // Check if the download has completed...
+                    Cursor c = manager.query(new DownloadManager.Query()
+                            .setFilterById(downloadId)
+                            .setFilterByStatus(DownloadManager.STATUS_SUCCESSFUL | DownloadManager.STATUS_FAILED)
+                    );
+                    if (c.moveToFirst()) {
+                        int status = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
+                        Log.d("Commons", "Download completed with status " + status);
+                        if (status == DownloadManager.STATUS_SUCCESSFUL) {
+                            // Force Gallery to index the new file
+                            Uri mediaUri = Uri.parse("file://" + Environment.getExternalStorageDirectory());
+                            getSherlockActivity().sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, mediaUri));
+
+                            // todo: show a persistent notification?
+                        }
+                    } else {
+                        Log.d("Commons", "Couldn't get download status for some reason");
+                    }
+                    getSherlockActivity().unregisterReceiver(this);
+                }
+            };
+            getSherlockActivity().registerReceiver(onComplete, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
+        }
+    }
+
     @Override
     public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
         if(!editable) { // Disable menu options for editable views
@@ -159,6 +229,7 @@ public class MediaDetailPagerFragment extends SherlockFragment implements ViewPa
                     // Crude way of checking if the file has been successfully saved!
                     menu.findItem(R.id.menu_browser_current_image).setEnabled(false).setVisible(false);
                     menu.findItem(R.id.menu_share_current_image).setEnabled(false).setVisible(false);
+                    menu.findItem(R.id.menu_download_current_image).setEnabled(false).setVisible(false);
                     menu.findItem(R.id.menu_retry_current_image).setEnabled(true).setVisible(true);
                     menu.findItem(R.id.menu_abort_current_image).setEnabled(true).setVisible(true);
                     return;