Add GlideModule for lazily initialization.

Fixes #299.

integration/okhttp/src/main/AndroidManifest.xml

 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.bumptech.glide.integration.okhttp">
-    <application />
-
+    <application>
+        <meta-data
+            android:name="com.bumptech.glide.integration.okhttp.OkHttpGlideModule"
+            android:value="GlideModule" />
+    </application>
 </manifest>

integration/okhttp/src/main/java/com/bumptech/glide/integration/okhttp/OkHttpGlideModule.java

+package com.bumptech.glide.integration.okhttp;
+
+import android.content.Context;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.load.model.GlideUrl;
+import com.bumptech.glide.module.GlideModule;
+
+import java.io.InputStream;
+
+/**
+ * A {@link com.bumptech.glide.module.GlideModule} implementation to replace Glide's default
+ * {@link java.net.HttpURLConnection} based {@link com.bumptech.glide.load.model.ModelLoader} with an OkHttp based
+ * {@link com.bumptech.glide.load.model.ModelLoader}.
+ *
+ * <p>
+ *     If you're using gradle, you can include this module simply by depending on the aar, the module will be merged
+ *     in by manifest merger. For other build systems or for more more information, see
+ *     {@link com.bumptech.glide.module.GlideModule}.
+ * </p>
+ */
+public class OkHttpGlideModule implements GlideModule {
+    @Override
+    public void initialize(Context context, Glide glide) {
+        glide.register(GlideUrl.class, InputStream.class, new OkHttpUrlLoader.Factory());
+    }
+}

integration/volley/src/main/AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
           package="com.bumptech.glide.integration.volley">
-  <application />
+  <application>
+      <meta-data
+          android:name="com.bumptech.glide.integration.volley.VolleyGlideModule"
+          android:value="GlideModule" />
+  </application>
 </manifest>

integration/volley/src/main/java/com/bumptech/glide/integration/volley/VolleyGlideModule.java

+package com.bumptech.glide.integration.volley;
+
+import android.content.Context;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.load.model.GlideUrl;
+import com.bumptech.glide.module.GlideModule;
+
+import java.io.InputStream;
+
+/**
+ * A {@link com.bumptech.glide.module.GlideModule} implementation to replace Glide's default
+ * {@link java.net.HttpURLConnection} based {@link com.bumptech.glide.load.model.ModelLoader} with a Volley based
+ * {@link com.bumptech.glide.load.model.ModelLoader}.
+ *
+ * <p>
+ *     If you're using gradle, you can include this module simply by depending on the aar, the module will be merged
+ *     in by manifest merger. For other build systems or for more more information, see
+ *     {@link com.bumptech.glide.module.GlideModule}.
+ * </p>
+ */
+public class VolleyGlideModule implements GlideModule {
+    @Override
+    public void initialize(Context context, Glide glide) {
+        glide.register(GlideUrl.class, InputStream.class, new VolleyUrlLoader.Factory(context));
+    }
+}

library/src/androidTest/java/com/bumptech/glide/module/ManifestParserTest.java

+package com.bumptech.glide.module;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.Matchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.os.Bundle;
+
+import com.bumptech.glide.Glide;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+import java.util.List;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE, emulateSdk = 18)
+public class ManifestParserTest {
+    private static final String MODULE_VALUE = "GlideModule";
+
+    @Mock Context context;
+    private ManifestParser parser;
+    private ApplicationInfo applicationInfo;
+
+    @Before
+    public void setUp() throws PackageManager.NameNotFoundException {
+        MockitoAnnotations.initMocks(this);
+        applicationInfo = new ApplicationInfo();
+        applicationInfo.metaData = new Bundle();
+
+        String packageName = "com.bumptech.test";
+        when(context.getPackageName()).thenReturn(packageName);
+
+        PackageManager pm = mock(PackageManager.class);
+        when(pm.getApplicationInfo(eq(packageName), eq(PackageManager.GET_META_DATA)))
+                .thenReturn(applicationInfo);
+        when(context.getPackageManager()).thenReturn(pm);
+
+        parser = new ManifestParser(context);
+    }
+
+    @Test
+    public void testParse_returnsEmptyListIfNoModulesListed() {
+        assertThat(parser.parse()).isEmpty();
+    }
+
+    @Test
+    public void testParse_withSingleValidModuleName_returnsListContainingModule() {
+        addModuleToManifest(TestModule1.class);
+
+        List<GlideModule> modules = parser.parse();
+        assertThat(modules).hasSize(1);
+        assertThat(modules.get(0)).isInstanceOf(TestModule1.class);
+    }
+
+    @Test
+    public void testParse_withMultipleValidModuleNames_returnsListContainingModules() {
+        addModuleToManifest(TestModule1.class);
+        addModuleToManifest(TestModule2.class);
+
+        List<GlideModule> modules = parser.parse();
+        assertThat(modules).hasSize(2);
+
+        assertThat(modules).contains(new TestModule1());
+        assertThat(modules).contains(new TestModule2());
+    }
+
+    @Test
+    public void testParse_withValidModuleName_ignoresMetadataWithoutGlideModuleValue() {
+        applicationInfo.metaData.putString(TestModule1.class.getName(), MODULE_VALUE + "test");
+
+        assertThat(parser.parse()).isEmpty();
+    }
+
+    @Test(expected = RuntimeException.class)
+    public void testThrows_whenModuleNameNotFound() {
+        addToManifest("fakeClassName");
+
+        parser.parse();
+    }
+
+    @Test(expected = RuntimeException.class)
+    public void testThrows_whenClassInManifestIsNotAModule() {
+        addModuleToManifest(InvalidClass.class);
+
+        parser.parse();
+    }
+
+    @Test(expected = RuntimeException.class)
+    public void testThrows_whenPackageNameNotFound() {
+        when(context.getPackageName()).thenReturn("fakePackageName");
+
+        parser.parse();
+    }
+
+    private void addModuleToManifest(Class<?> moduleClass) {
+        addToManifest(moduleClass.getName());
+    }
+
+    private void addToManifest(String key) {
+        applicationInfo.metaData.putString(key, MODULE_VALUE);
+    }
+
+    public static class InvalidClass { }
+
+    public static class TestModule1 implements GlideModule {
+        @Override
+        public void initialize(Context context, Glide glide) { }
+
+        @Override
+        public boolean equals(Object o) {
+            return o instanceof TestModule1;
+        }
+
+        @Override
+        public int hashCode() {
+            return super.hashCode();
+        }
+    }
+
+    public static class TestModule2 implements GlideModule {
+
+        @Override
+        public void initialize(Context context, Glide glide) { }
+
+        @Override
+        public boolean equals(Object o) {
+            return o instanceof TestModule2;
+        }
+
+        @Override
+        public int hashCode() {
+            return super.hashCode();
+        }
+    }
+}
\ No newline at end of file

library/src/main/java/com/bumptech/glide/Glide.java

@@ -56,6 +56,8 @@ import com.bumptech.glide.load.resource.transcode.GlideBitmapDrawableTranscoder;
 import com.bumptech.glide.load.resource.transcode.ResourceTranscoder;
 import com.bumptech.glide.load.resource.transcode.TranscoderRegistry;
 import com.bumptech.glide.manager.RequestManagerRetriever;
+import com.bumptech.glide.module.GlideModule;
+import com.bumptech.glide.module.ManifestParser;
 import com.bumptech.glide.provider.DataLoadProvider;
 import com.bumptech.glide.provider.DataLoadProviderRegistry;
 import com.bumptech.glide.request.FutureTarget;
@@ -241,6 +243,10 @@ public class Glide {
 
         bitmapFitCenter = new FitCenter(bitmapPool);
         drawableFitCenter = new GifBitmapWrapperTransformation(bitmapPool, bitmapFitCenter);
+
+        for (GlideModule module : new ManifestParser(context).parse()) {
+            module.initialize(context, this);
+        }
     }
 
     /**

library/src/main/java/com/bumptech/glide/module/GlideModule.java

+package com.bumptech.glide.module;
+
+import android.content.Context;
+
+import com.bumptech.glide.Glide;
+
+/**
+ * An interface allowing lazy registration of {@link com.bumptech.glide.load.model.ModelLoader ModelLoaders}.
+ *
+ * <p>
+ *     To use this interface:
+ *     <ol>
+ *         <li>
+ *             Implement the GlideModule interface in a class with public visibility, calling
+ *             {@link com.bumptech.glide.Glide#register(Class, Class, com.bumptech.glide.load.model.ModelLoaderFactory)}
+ *             for each {@link com.bumptech.glide.load.model.ModelLoader} you'd like to register:
+ *             <pre>
+ *                  <code>
+ *                      public class FlickrGlideModule implements GlideModule {
+ *                          {@literal @}Override
+ *                          public void initialize(Context context, Glide glide) {
+ *                              glide.register(Model.class, Data.class, new MyModelLoader());
+ *                          }
+ *                      }
+ *                  </code>
+ *             </pre>
+ *         </li>
+ *         <li>
+ *              Add your implementation to your list of keeps in your proguard.cfg file:
+ *              <pre>
+ *                  {@code
+ *                      -keepnames class * com.bumptech.glide.samples.flickr.FlickrGlideModule
+ *                  }
+ *              </pre>
+ *         </li>
+ *         <li>
+ *             Add a metadata tag to your AndroidManifest.xml with your GlideModule implementation's fully qualified
+ *             classname as the key, and {@code GlideModule} as the value:
+ *             <pre>
+ *                 {@code
+ *                      <meta-data
+ *                          android:name="com.bumptech.glide.samples.flickr.FlickrGlideModule"
+ *                          android:value="GlideModule" />
+ *                 }
+ *             </pre>
+ *         </li>
+ *     </ol>
+ * </p>
+ *
+ * <p>
+ *     All implementations must be publicly visible and contain only an empty constructor so they can be instantiated
+ *     via reflection when Glide is lazily initialized.
+ * </p>
+ */
+public interface GlideModule {
+    void initialize(Context context, Glide glide);
+}

library/src/main/java/com/bumptech/glide/module/ManifestParser.java

+package com.bumptech.glide.module;
+
+import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Parses {@link com.bumptech.glide.module.GlideModule} references out of the AndroidManifest file.
+ */
+public final class ManifestParser {
+    private static final String GLIDE_MODULE_VALUE = "GlideModule";
+
+    private final Context context;
+
+    public ManifestParser(Context context) {
+        this.context = context;
+    }
+
+    public List<GlideModule> parse() {
+        List<GlideModule> modules = new ArrayList<GlideModule>();
+        try {
+            ApplicationInfo appInfo = context.getPackageManager().getApplicationInfo(
+                    context.getPackageName(), PackageManager.GET_META_DATA);
+            if (appInfo.metaData != null) {
+                for (String key : appInfo.metaData.keySet()) {
+                    if (GLIDE_MODULE_VALUE.equals(appInfo.metaData.getString(key))) {
+                        modules.add(parseModule(key));
+                    }
+                }
+            }
+        } catch (PackageManager.NameNotFoundException e) {
+            throw new RuntimeException("Unable to find metadata to parse GlideModules", e);
+        }
+
+        return modules;
+    }
+
+    private static GlideModule parseModule(String className) {
+        Class<?> clazz;
+        try {
+            clazz = Class.forName(className);
+        } catch (ClassNotFoundException e) {
+            throw new IllegalArgumentException("Unable to find GlideModule implementation", e);
+        }
+
+        Object module;
+        try {
+            module = clazz.newInstance();
+        } catch (InstantiationException e) {
+            throw new RuntimeException("Unable to instantiate GlideModule implementation for " + clazz, e);
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException("Unable to instantiate GlideModule implementation for " + clazz, e);
+        }
+
+        if (!(module instanceof GlideModule)) {
+            throw new RuntimeException("Expected instanceof GlideModule, but found: " + module);
+        }
+        return (GlideModule) module;
+    }
+}

samples/flickr/src/main/AndroidManifest.xml

@@ -23,6 +23,9 @@
 
     <activity android:name=".FullscreenActivity" />
 
+    <meta-data
+        android:name="com.bumptech.glide.samples.flickr.FlickrGlideModule"
+        android:value="GlideModule" />
   </application>
 
 </manifest>

samples/flickr/src/main/java/com/bumptech/glide/samples/flickr/FlickrGlideModule.java

+package com.bumptech.glide.samples.flickr;
+
+import android.content.Context;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.module.GlideModule;
+import com.bumptech.glide.samples.flickr.api.Photo;
+
+import java.io.InputStream;
+
+/**
+ * {@link com.bumptech.glide.module.GlideModule} for the Flickr sample app.
+ */
+public class FlickrGlideModule implements GlideModule {
+    @Override
+    public void initialize(Context context, Glide glide) {
+        glide.register(Photo.class, InputStream.class, new FlickrModelLoader.Factory());
+    }
+}

samples/flickr/src/main/java/com/bumptech/glide/samples/flickr/FlickrSearchActivity.java

@@ -33,7 +33,6 @@ import com.bumptech.glide.samples.flickr.api.Api;
 import com.bumptech.glide.samples.flickr.api.Photo;
 
 import java.io.File;
-import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -90,7 +89,6 @@ public class FlickrSearchActivity extends ActionBarActivity {
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        Glide.get(this).register(Photo.class, InputStream.class, new FlickrModelLoader.Factory());
         backgroundThread = new HandlerThread("BackgroundThumbnailHandlerThread");
         backgroundThread.start();
         backgroundHandler = new Handler(backgroundThread.getLooper());

samples/giphy/src/main/AndroidManifest.xml

@@ -19,6 +19,10 @@
             </intent-filter>
         </activity>
         <activity android:name=".FullscreenActivity" />
+
+        <meta-data
+            android:name="com.bumptech.glide.samples.giphy.GiphyGlideModule"
+            android:value="GlideModule" />
     </application>
 
 </manifest>

samples/giphy/src/main/java/com/bumptech/glide/samples/giphy/GiphyGlideModule.java

+package com.bumptech.glide.samples.giphy;
+
+import android.content.Context;
+
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.module.GlideModule;
+
+import java.io.InputStream;
+
+/**
+ * {@link com.bumptech.glide.module.GlideModule} implementation for the Giphy sample app.
+ */
+public class GiphyGlideModule implements GlideModule {
+    @Override
+    public void initialize(Context context, Glide glide) {
+        glide.register(Api.GifResult.class, InputStream.class, new GiphyModelLoader.Factory());
+    }
+}

samples/giphy/src/main/java/com/bumptech/glide/samples/giphy/MainActivity.java

@@ -20,7 +20,6 @@ import com.bumptech.glide.ListPreloader;
 import com.bumptech.glide.load.engine.DiskCacheStrategy;
 import com.bumptech.glide.util.ViewPreloadSizeProvider;
 
-import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -31,15 +30,12 @@ public class MainActivity extends Activity implements Api.Monitor {
     private static final String TAG = "GiphyActivity";
 
     private GifAdapter adapter;
-    private DrawableRequestBuilder<Api.GifResult> gifItemRequest;
-    private ViewPreloadSizeProvider<Api.GifResult> preloadSizeProvider;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
 
-        Glide.get(this).register(Api.GifResult.class, InputStream.class, new GiphyModelLoader.Factory());
 
         ImageView giphyLogoView = (ImageView) findViewById(R.id.giphy_logo_view);
         Glide.with(this)
@@ -49,12 +45,12 @@ public class MainActivity extends Activity implements Api.Monitor {
 
         ListView gifList = (ListView) findViewById(R.id.gif_list);
 
-        gifItemRequest = Glide.with(this)
+        DrawableRequestBuilder<Api.GifResult> gifItemRequest = Glide.with(this)
                 .from(Api.GifResult.class)
                 .diskCacheStrategy(DiskCacheStrategy.SOURCE)
                 .fitCenter();
 
-        preloadSizeProvider = new ViewPreloadSizeProvider<Api.GifResult>();
+        ViewPreloadSizeProvider<Api.GifResult> preloadSizeProvider = new ViewPreloadSizeProvider<Api.GifResult>();
         adapter = new GifAdapter(this, gifItemRequest, preloadSizeProvider);
         gifList.setAdapter(adapter);
         ListPreloader<Api.GifResult> preloader = new ListPreloader<Api.GifResult>(adapter, preloadSizeProvider, 2);