Support multiple listeners in a Glide request.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=191378721

Author: adrianv

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

@@ -34,6 +34,8 @@
 import com.bumptech.glide.util.Util;
 import java.io.File;
 import java.net.URL;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * A generic class that can handle setting options and staring loads for generic resource types.
@@ -66,7 +68,7 @@ public class RequestBuilder<TranscodeType> implements Cloneable,
   @Nullable private Object model;
   // model may occasionally be null, so to enforce that load() was called, put a boolean rather
   // than relying on model not to be null.
-  @Nullable private RequestListener<TranscodeType> requestListener;
+  @Nullable private List<RequestListener<TranscodeType>> requestListeners;
   @Nullable private RequestBuilder<TranscodeType> thumbnailBuilder;
   @Nullable private RequestBuilder<TranscodeType> errorBuilder;
   @Nullable private Float thumbSizeMultiplier;
@@ -144,6 +146,9 @@ public RequestBuilder<TranscodeType> transition(
    * instance of an exception handler per type of request (usually activity/fragment) rather than
    * pass one in per request to avoid some redundant object allocation.
    *
+   * <p>Subsequent calls to this method will replace previously set listeners. To set multiple
+   * listeners, use {@link #addListener} instead.
+   *
    * @param requestListener The request listener to use.
    * @return This request builder.
    */
@@ -152,8 +157,27 @@ public RequestBuilder<TranscodeType> transition(
   @SuppressWarnings("unchecked")
   public RequestBuilder<TranscodeType> listener(
       @Nullable RequestListener<TranscodeType> requestListener) {
-    this.requestListener = requestListener;
+    this.requestListeners = null;
+    return addListener(requestListener);
+  }
 
+  /**
+   * Adds a {@link RequestListener}. If called multiple times, all passed
+   * {@link RequestListener listeners} will be called in order.
+   *
+   * @param requestListener The request listener to use. If {@code null}, this method is a noop.
+   * @return This request builder.
+   */
+  @NonNull
+  @CheckResult
+  public RequestBuilder<TranscodeType> addListener(
+      @Nullable RequestListener<TranscodeType> requestListener) {
+    if (requestListener != null) {
+      if (this.requestListeners == null) {
+        this.requestListeners = new ArrayList<>();
+      }
+      this.requestListeners.add(requestListener);
+    }
     return this;
   }
 
@@ -1041,7 +1065,7 @@ private Request obtainRequest(
         priority,
         target,
         targetListener,
-        requestListener,
+        requestListeners,
         requestCoordinator,
         glideContext.getEngine(),
         transitionOptions.getTransitionFactory());

library/src/main/java/com/bumptech/glide/request/SingleRequest.java

@@ -24,6 +24,7 @@
 import com.bumptech.glide.util.Util;
 import com.bumptech.glide.util.pool.FactoryPools;
 import com.bumptech.glide.util.pool.StateVerifier;
+import java.util.List;
 
 /**
  * A {@link Request} that loads a {@link com.bumptech.glide.load.engine.Resource} into a given
@@ -103,7 +104,7 @@ private enum Status {
   private int overrideHeight;
   private Priority priority;
   private Target<R> target;
-  private RequestListener<R> requestListener;
+  @Nullable private List<RequestListener<R>> requestListeners;
   private Engine engine;
   private TransitionFactory<? super R> animationFactory;
   private Resource<R> resource;
@@ -127,7 +128,7 @@ public static <R> SingleRequest<R> obtain(
       Priority priority,
       Target<R> target,
       RequestListener<R> targetListener,
-      RequestListener<R> requestListener,
+      @Nullable List<RequestListener<R>> requestListeners,
       RequestCoordinator requestCoordinator,
       Engine engine,
       TransitionFactory<? super R> animationFactory) {
@@ -147,7 +148,7 @@ public static <R> SingleRequest<R> obtain(
         priority,
         target,
         targetListener,
-        requestListener,
+        requestListeners,
         requestCoordinator,
         engine,
         animationFactory);
@@ -171,7 +172,7 @@ private void init(
       Priority priority,
       Target<R> target,
       RequestListener<R> targetListener,
-      RequestListener<R> requestListener,
+      @Nullable List<RequestListener<R>> requestListeners,
       RequestCoordinator requestCoordinator,
       Engine engine,
       TransitionFactory<? super R> animationFactory) {
@@ -185,7 +186,7 @@ private void init(
     this.priority = priority;
     this.target = target;
     this.targetListener = targetListener;
-    this.requestListener = requestListener;
+    this.requestListeners = requestListeners;
     this.requestCoordinator = requestCoordinator;
     this.engine = engine;
     this.animationFactory = animationFactory;
@@ -209,7 +210,7 @@ public void recycle() {
     overrideWidth = -1;
     overrideHeight = -1;
     target = null;
-    requestListener = null;
+    requestListeners = null;
     targetListener = null;
     requestCoordinator = null;
     animationFactory = null;
@@ -570,10 +571,18 @@ private void onResourceReady(Resource<R> resource, R result, DataSource dataSour
 
     isCallingCallbacks = true;
     try {
-      if ((requestListener == null
-          || !requestListener.onResourceReady(result, model, target, dataSource, isFirstResource))
-          && (targetListener == null
-          || !targetListener.onResourceReady(result, model, target, dataSource, isFirstResource))) {
+      boolean anyListenerHandledUpdatingTarget = false;
+      if (requestListeners != null) {
+        for (RequestListener<R> listener : requestListeners) {
+          anyListenerHandledUpdatingTarget |=
+              listener.onResourceReady(result, model, target, dataSource, isFirstResource);
+        }
+      }
+      anyListenerHandledUpdatingTarget |=
+          targetListener != null
+              && targetListener.onResourceReady(result, model, target, dataSource, isFirstResource);
+
+      if (!anyListenerHandledUpdatingTarget) {
         Transition<? super R> animation =
             animationFactory.build(dataSource, isFirstResource);
         target.onResourceReady(result, animation);
@@ -609,10 +618,18 @@ private void onLoadFailed(GlideException e, int maxLogLevel) {
     isCallingCallbacks = true;
     try {
       //TODO: what if this is a thumbnail request?
-      if ((requestListener == null
-          || !requestListener.onLoadFailed(e, model, target, isFirstReadyResource()))
-          && (targetListener == null
-          || !targetListener.onLoadFailed(e, model, target, isFirstReadyResource()))) {
+      boolean anyListenerHandledUpdatingTarget = false;
+      if (requestListeners != null) {
+        for (RequestListener<R> listener : requestListeners) {
+          anyListenerHandledUpdatingTarget |=
+              listener.onLoadFailed(e, model, target, isFirstReadyResource());
+        }
+      }
+      anyListenerHandledUpdatingTarget |=
+          targetListener != null
+              && targetListener.onLoadFailed(e, model, target, isFirstReadyResource());
+
+      if (!anyListenerHandledUpdatingTarget) {
         setErrorPlaceholder();
       }
     } finally {
@@ -633,14 +650,19 @@ public boolean isEquivalentTo(Request o) {
           && requestOptions.equals(that.requestOptions)
           && priority == that.priority
           // We do not want to require that RequestListeners implement equals/hashcode, so we don't
-          // compare them using equals(). We can however, at least assert that the request listener
-          // is either present or not present in both requests.
-          && (requestListener != null
-          ? that.requestListener != null : that.requestListener == null);
+          // compare them using equals(). We can however, at least assert that the same amount of
+          // request listeners are present in both requests
+          && listenerCountEquals(this, that);
     }
     return false;
   }
 
+  private static boolean listenerCountEquals(SingleRequest<?> first, SingleRequest<?> second) {
+    int firstListenerCount = first.requestListeners == null ? 0 : first.requestListeners.size();
+    int secondListenerCount = second.requestListeners == null ? 0 : second.requestListeners.size();
+    return firstListenerCount == secondListenerCount;
+  }
+
   private void logV(String message) {
     Log.v(TAG, message + " this: " + tag);
   }

library/test/src/test/java/com/bumptech/glide/RequestBuilderTest.java

@@ -2,16 +2,22 @@
 
 import static com.bumptech.glide.tests.BackgroundUtil.testInBackground;
 import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyBoolean;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Matchers.isA;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import android.app.Application;
 import android.widget.ImageView;
+import com.bumptech.glide.load.DataSource;
+import com.bumptech.glide.load.resource.SimpleResource;
 import com.bumptech.glide.request.Request;
+import com.bumptech.glide.request.RequestListener;
 import com.bumptech.glide.request.RequestOptions;
+import com.bumptech.glide.request.SingleRequest;
 import com.bumptech.glide.request.target.Target;
 import com.bumptech.glide.request.target.ViewTarget;
 import com.bumptech.glide.tests.BackgroundUtil.BackgroundTester;
@@ -20,6 +26,8 @@
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.robolectric.RobolectricTestRunner;
@@ -32,8 +40,12 @@
 public class RequestBuilderTest {
   @Rule public TearDownGlide tearDownGlide = new TearDownGlide();
 
+  @Mock private RequestListener<Object> listener1;
+  @Mock private RequestListener<Object> listener2;
+  @Mock private Target<Object> target;
   @Mock private GlideContext glideContext;
   @Mock private RequestManager requestManager;
+  @Captor private ArgumentCaptor<SingleRequest<Object>> requestCaptor;
   private Glide glide;
   private Application context;
 
@@ -57,12 +69,11 @@ public void testThrowsWhenTransitionsOptionsIsNull() {
 
   @Test
   public void testDoesNotThrowWithNullModelWhenRequestIsBuilt() {
-    getNullModelRequest().into(mock(Target.class));
+    getNullModelRequest().into(target);
   }
 
   @Test
   public void testAddsNewRequestToRequestTracker() {
-    Target<Object> target = mock(Target.class);
     getNullModelRequest().into(target);
 
     verify(requestManager).track(eq(target), isA(Request.class));
@@ -71,7 +82,6 @@ public void testAddsNewRequestToRequestTracker() {
   @Test
   public void testRemovesPreviousRequestFromRequestTracker() {
     Request previous = mock(Request.class);
-    Target<Object> target = mock(Target.class);
     when(target.getRequest()).thenReturn(previous);
 
     getNullModelRequest().into(target);
@@ -112,6 +122,35 @@ public void runTest() {
     });
   }
 
+  @Test
+  public void testMultipleRequestListeners() {
+    getNullModelRequest().addListener(listener1).addListener(listener2).into(target);
+    verify(requestManager).track(any(Target.class), requestCaptor.capture());
+    requestCaptor.getValue().onResourceReady(new SimpleResource<>(new Object()), DataSource.LOCAL);
+
+    verify(listener1)
+        .onResourceReady(
+            any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+    verify(listener2)
+        .onResourceReady(
+            any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+  }
+
+  @Test
+  public void testListenerApiOverridesListeners() {
+    getNullModelRequest().addListener(listener1).listener(listener2).into(target);
+    verify(requestManager).track(any(Target.class), requestCaptor.capture());
+    requestCaptor.getValue().onResourceReady(new SimpleResource<>(new Object()), DataSource.LOCAL);
+
+    // The #listener API removes any previous listeners, so the first listener should not be called.
+    verify(listener1, never())
+        .onResourceReady(
+            any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+    verify(listener2)
+        .onResourceReady(
+            any(), any(), isA(Target.class), isA(DataSource.class), anyBoolean());
+  }
+
   private RequestBuilder<Object> getNullModelRequest() {
     when(glideContext.buildImageViewTarget(isA(ImageView.class), isA(Class.class)))
         .thenReturn(mock(ViewTarget.class));