Never fallback to UIL for handling image downloads, only use for displaying.

Our `IconDownloader` extended `BaseImageDownloader` from UIL. There was an
explicit check in the F-Droid `IconDownloader` which looks for
HTTP/HTTPS/Bluetooth schemes. If it wasn't one of these, it fell back
to the base class. This was what was happening for local cached image
files. As such, when the `getInputStream(...)` method was refactored
to only use F-Droids `DownloadFactory` and not delegate to the base class,
it failed on local "file://" URLs.

This change introduces a `LocalFileDownloader` and makes the `DownloaderFactory`
aware of it.

The `BaseImageDownloader` class only provides support for the following schemes:

 * HTTP
 * HTTPS
 * File
 * Android content providers
 * Android assets
 * Android drawables

F-Droid now supports HTTP, HTTPS, and File URLs. There is not currently any
need for content proiders, assets or drawables to get icons for apps in F-Droid.
If there is a need in the future (e.g. an issue currently discusses loading
icons from installed apps if possible) then that specific `Downloader` can get
introduced to solve the problem.

F-Droid/src/org/fdroid/fdroid/net/DownloaderFactory.java

@@ -48,9 +48,10 @@ public class DownloaderFactory {
         if (isBluetoothAddress(url)) {
             String macAddress = url.getHost().replace("-", ":");
             return new BluetoothDownloader(context, macAddress, url, destFile);
-        }
-        if (isOnionAddress(url)) {
+        } else if (isOnionAddress(url)) {
             return new TorHttpDownloader(context, url, destFile);
+        } else if (isLocalFile(url)) {
+            return new LocalFileDownloader(context, url, destFile);
         }
         return new HttpDownloader(context, url, destFile);
     }
@@ -59,6 +60,10 @@ public class DownloaderFactory {
         return "bluetooth".equalsIgnoreCase(url.getProtocol());
     }
 
+    static boolean isLocalFile(URL url) {
+        return "file".equalsIgnoreCase(url.getProtocol());
+    }
+
     public static AsyncDownloader createAsync(Context context, String urlString, File destFile, String title, String id, AsyncDownloader.Listener listener) throws IOException {
         return createAsync(context, new URL(urlString), destFile, title, id, listener);
     }

F-Droid/src/org/fdroid/fdroid/net/IconDownloader.java

@@ -2,19 +2,17 @@ package org.fdroid.fdroid.net;
 
 import android.content.Context;
 
-import com.nostra13.universalimageloader.core.download.BaseImageDownloader;
+import com.nostra13.universalimageloader.core.download.ImageDownloader;
 
 import java.io.IOException;
 import java.io.InputStream;
 
-public class IconDownloader extends BaseImageDownloader {
+public class IconDownloader implements ImageDownloader {
+
+    private final Context context;
 
     public IconDownloader(Context context) {
-        super(context);
-    }
-
-    public IconDownloader(Context context, int connectTimeout, int readTimeout) {
-        super(context, connectTimeout, readTimeout);
+        this.context = context;
     }
 
     @Override
@@ -22,5 +20,4 @@ public class IconDownloader extends BaseImageDownloader {
         return DownloaderFactory.create(context, imageUri).getInputStream();
     }
 
-
 }

F-Droid/src/org/fdroid/fdroid/net/LocalFileDownloader.java

@@ -0,0 +1,52 @@
+package org.fdroid.fdroid.net;
+
+import android.content.Context;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+public class LocalFileDownloader extends Downloader {
+
+    LocalFileDownloader(Context context, URL url, File destFile) throws FileNotFoundException, MalformedURLException {
+        super(context, url, destFile);
+    }
+
+    private File getFileToDownload() {
+        return new File(sourceUrl.getPath());
+    }
+
+    @Override
+    protected InputStream getDownloadersInputStream() throws IOException {
+        return new FileInputStream(getFileToDownload());
+    }
+
+    @Override
+    protected void close() throws IOException {
+        // Do nothing.
+    }
+
+    @Override
+    public boolean hasChanged() {
+        return false;
+    }
+
+    @Override
+    public int totalDownloadSize() {
+        return 0;
+    }
+
+    @Override
+    public void download() throws IOException, InterruptedException {
+        downloadFromStream(1024 * 50);
+    }
+
+    @Override
+    public boolean isCached() {
+        return false;
+    }
+}