1 files changed, 164 insertions, 0 deletions
diff --git a/mobile/android/base/java/org/mozilla/gecko/home/ImageLoader.java b/mobile/android/base/java/org/mozilla/gecko/home/ImageLoader.java
new file mode 100644
index 000000000..2bbd82a8d
--- /dev/null
+++ b/mobile/android/base/java/org/mozilla/gecko/home/ImageLoader.java
@@ -0,0 +1,164 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.home;
+
+import android.content.Context;
+import android.net.Uri;
+import android.util.DisplayMetrics;
+import android.util.Log;
+
+import com.squareup.picasso.LruCache;
+import com.squareup.picasso.Picasso;
+import com.squareup.picasso.Downloader.Response;
+import com.squareup.picasso.UrlConnectionDownloader;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.EnumSet;
+import java.util.Set;
+
+import org.mozilla.gecko.distribution.Distribution;
+
+public class ImageLoader {
+    private static final String LOGTAG = "GeckoImageLoader";
+
+    private static final String DISTRIBUTION_SCHEME = "gecko.distribution";
+    private static final String SUGGESTED_SITES_AUTHORITY = "suggestedsites";
+
+    // The order of density factors to try when looking for an image resource
+    // in the distribution directory. It looks for an exact match first (1.0) then
+    // tries to find images with higher density (2.0 and 1.5). If no image is found,
+    // try a lower density (0.5). See loadDistributionImage().
+    private static final float[] densityFactors = new float[] { 1.0f, 2.0f, 1.5f, 0.5f };
+
+    private static enum Density {
+        MDPI,
+        HDPI,
+        XHDPI,
+        XXHDPI;
+
+        @Override
+        public String toString() {
+            return super.toString().toLowerCase();
+        }
+    }
+
+    // Picasso instance and LruCache lrucache are protected by synchronization.
+    private static Picasso instance;
+    private static LruCache lrucache;
+
+    public static synchronized Picasso with(Context context) {
+        if (instance == null) {
+            lrucache = new LruCache(context);
+            Picasso.Builder builder = new Picasso.Builder(context).memoryCache(lrucache);
+
+            final Distribution distribution = Distribution.getInstance(context.getApplicationContext());
+            builder.downloader(new ImageDownloader(context, distribution));
+            instance = builder.build();
+        }
+
+        return instance;
+    }
+
+    public static synchronized void clearLruCache() {
+        if (lrucache != null) {
+            lrucache.evictAll();
+        }
+    }
+
+    /**
+     * Custom Downloader built on top of Picasso's UrlConnectionDownloader
+     * that supports loading images from custom URIs.
+     */
+    public static class ImageDownloader extends UrlConnectionDownloader {
+        private final Context context;
+        private final Distribution distribution;
+
+        public ImageDownloader(Context context, Distribution distribution) {
+            super(context);
+            this.context = context;
+            this.distribution = distribution;
+        }
+
+        private Density getDensity(float factor) {
+            final DisplayMetrics dm = context.getResources().getDisplayMetrics();
+            final float densityDpi = dm.densityDpi * factor;
+
+            if (densityDpi >= DisplayMetrics.DENSITY_XXHIGH) {
+                return Density.XXHDPI;
+            } else if (densityDpi >= DisplayMetrics.DENSITY_XHIGH) {
+                return Density.XHDPI;
+            } else if (densityDpi >= DisplayMetrics.DENSITY_HIGH) {
+                return Density.HDPI;
+            }
+
+            // Fallback to mdpi, no need to handle ldpi.
+            return Density.MDPI;
+        }
+
+        @Override
+        public Response load(Uri uri, boolean localCacheOnly) throws IOException {
+            final String scheme = uri.getScheme();
+            if (DISTRIBUTION_SCHEME.equals(scheme)) {
+                return loadDistributionImage(uri);
+            }
+
+            return super.load(uri, localCacheOnly);
+        }
+
+        private static String getPathForDensity(String basePath, Density density,
+                                                String filename) {
+            final File dir = new File(basePath, density.toString());
+            return String.format("%s/%s.png", dir.toString(), filename);
+        }
+
+        /**
+         * Handle distribution URIs in Picasso. The expected format is:
+         *
+         *   gecko.distribution://<basepath>/<imagename>
+         *
+         * Which will look for the following file in the distribution:
+         *
+         *   <distribution-root-dir>/<basepath>/<device-density>/<imagename>.png
+         */
+        private Response loadDistributionImage(Uri uri) throws IOException {
+            // Eliminate the leading '//'
+            final String ssp = uri.getSchemeSpecificPart().substring(2);
+
+            final String filename;
+            final String basePath;
+
+            final int slashIndex = ssp.lastIndexOf('/');
+            if (slashIndex == -1) {
+                filename = ssp;
+                basePath = "";
+            } else {
+                filename = ssp.substring(slashIndex + 1);
+                basePath = ssp.substring(0, slashIndex);
+            }
+
+            Set<Density> triedDensities = EnumSet.noneOf(Density.class);
+
+            for (int i = 0; i < densityFactors.length; i++) {
+                final Density density = getDensity(densityFactors[i]);
+                if (!triedDensities.add(density)) {
+                    continue;
+                }
+
+                final String path = getPathForDensity(basePath, density, filename);
+                Log.d(LOGTAG, "Trying to load image from distribution " + path);
+
+                final File f = distribution.getDistributionFile(path);
+                if (f != null) {
+                    return new Response(new FileInputStream(f), true);
+                }
+            }
+
+            throw new ResponseException("Couldn't find suggested site image in distribution");
+        }
+    }
+}