Override default Encoders (#2349)

* Add prepend methods for EncoderRegistry and ResourceEncoderRegistry classes

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

@@ -23,6 +23,7 @@
 import com.bumptech.glide.provider.ResourceDecoderRegistry;
 import com.bumptech.glide.provider.ResourceEncoderRegistry;
 import com.bumptech.glide.util.pool.FactoryPools;
+
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -65,11 +66,24 @@ public Registry() {
    * {@link java.io.FileInputStream} and any other subclass.
    *
    * <p>If multiple {@link Encoder}s are registered for the same type or super type, the
-   * {@link Encoder} that is registered first will be used. As a result, it's not currently possible
-   * to replace Glide's default {@link Encoder}s.
+   * {@link Encoder} that is registered first will be used.
    */
   public <Data> Registry register(Class<Data> dataClass, Encoder<Data> encoder) {
-    encoderRegistry.add(dataClass, encoder);
+    encoderRegistry.append(dataClass, encoder);
+    return this;
+  }
+
+  /**
+   * Prepends the given {@link Encoder} into the list of available {@link Encoder}s
+   * so that it is attempted before all later and default {@link Encoder}s for the given
+   * data class.
+   *
+   * <p>This method allows you to replace the default {@link Encoder} because it ensures
+   * the registered {@link Encoder} will run first. If multiple {@link Encoder}s are registered for
+   * the same type or super type, the {@link Encoder} that is registered first will be used.
+   */
+  public <Data> Registry prepend(Class<Data> dataClass, Encoder<Data> encoder) {
+    encoderRegistry.prepend(dataClass, encoder);
     return this;
   }
 
@@ -139,12 +153,30 @@ public <Data, TResource> Registry prepend(
    * {@link com.bumptech.glide.load.resource.gif.GifDrawable} and any other subclass.
    *
    * <p>If multiple {@link ResourceEncoder}s are registered for the same type or super type, the
-   * {@link ResourceEncoder} that is registered first will be used. As a result, it's not currently
-   * possible to replace Glide's default {@link ResourceEncoder}s.
+   * {@link ResourceEncoder} that is registered first will be used.
    */
   public <TResource> Registry register(Class<TResource> resourceClass,
       ResourceEncoder<TResource> encoder) {
-    resourceEncoderRegistry.add(resourceClass, encoder);
+    resourceEncoderRegistry.append(resourceClass, encoder);
+    return this;
+  }
+
+  /**
+   * Registers a new {@link com.bumptech.glide.load.data.DataRewinder.Factory} to handle a
+   * non-default data type that can be rewind to allow for efficient reads of file headers.
+   *
+   * Prepends the given {@link ResourceEncoder} into the list of available {@link ResourceEncoder}s
+   * so that it is attempted before all later and default {@link ResourceEncoder}s for the given
+   * data type.
+   *
+   * <p>This method allows you to replace the default {@link ResourceEncoder} because it ensures
+   * the registered {@link ResourceEncoder} will run first. If multiple {@link ResourceEncoder}s are
+   * registered for the same type or super type, the {@link ResourceEncoder} that is registered
+   * first will be used.
+   */
+  public <TResource> Registry prepend(Class<TResource> resourceClass,
+                                       ResourceEncoder<TResource> encoder) {
+    resourceEncoderRegistry.prepend(resourceClass, encoder);
     return this;
   }
 

library/src/main/java/com/bumptech/glide/provider/EncoderRegistry.java

@@ -7,7 +7,7 @@
 import java.util.List;
 
 /**
- * Contains an unordered list of {@link Encoder}s capable of encoding arbitrary data types.
+ * Contains an ordered list of {@link Encoder}s capable of encoding arbitrary data types.
  */
 public class EncoderRegistry {
   // TODO: This registry should probably contain a put, rather than a list.
@@ -24,10 +24,14 @@ public synchronized <T> Encoder<T> getEncoder(Class<T> dataClass) {
     return null;
   }
 
-  public synchronized <T> void add(Class<T> dataClass, Encoder<T> encoder) {
+  public synchronized <T> void append(Class<T> dataClass, Encoder<T> encoder) {
     encoders.add(new Entry<>(dataClass, encoder));
   }
 
+  public synchronized <T> void prepend(Class<T> dataClass, Encoder<T> encoder) {
+    encoders.add(0, new Entry<>(dataClass, encoder));
+  }
+
   private static final class Entry<T> {
     private final Class<T> dataClass;
     @Synthetic final Encoder<T> encoder;

library/src/main/java/com/bumptech/glide/provider/ResourceEncoderRegistry.java

@@ -1,23 +1,29 @@
 package com.bumptech.glide.provider;
 
 import android.support.annotation.Nullable;
+
 import com.bumptech.glide.load.ResourceEncoder;
 import com.bumptech.glide.util.Synthetic;
+
 import java.util.ArrayList;
 import java.util.List;
 
 /**
- * Contains an unordered list of {@link ResourceEncoder}s capable of encoding arbitrary resource
+ * Contains an ordered list of {@link ResourceEncoder}s capable of encoding arbitrary resource
  * types.
  */
 public class ResourceEncoderRegistry {
   // TODO: this should probably be a put.
   final List<Entry<?>> encoders = new ArrayList<>();
 
-  public synchronized <Z> void add(Class<Z> resourceClass, ResourceEncoder<Z> encoder) {
+  public synchronized <Z> void append(Class<Z> resourceClass, ResourceEncoder<Z> encoder) {
     encoders.add(new Entry<>(resourceClass, encoder));
   }
 
+  public synchronized <Z> void prepend(Class<Z> resourceClass, ResourceEncoder<Z> encoder) {
+    encoders.add(0, new Entry<>(resourceClass, encoder));
+  }
+
   @SuppressWarnings("unchecked")
   @Nullable
   public synchronized <Z> ResourceEncoder<Z> get(Class<Z> resourceClass) {