Support multiple sources

Summary:
The nodes version of D3364550. The only difference is that here we
don't get `onSizeChanged` but `onBoundsChanged`, and we need to compute the
height/width of the target image from those bounds. ahmedre please let me know
if any of these assumptions are in any way incorrect.

Reviewed By: ahmedre

Differential Revision: D3424843

ReactAndroid/src/main/java/com/facebook/react/flat/DrawImage.java

@@ -14,6 +14,7 @@ import javax.annotation.Nullable;
 import android.content.Context;
 
 import com.facebook.drawee.drawable.ScalingUtils.ScaleType;
+import com.facebook.react.bridge.ReadableArray;
 
 /**
  * Common interface for DrawImageWithPipeline and DrawImageWithDrawee.
@@ -28,7 +29,7 @@ import com.facebook.drawee.drawable.ScalingUtils.ScaleType;
   /**
    * Assigns a new image source to the DrawImage, or null to clear the image request.
    */
-  void setSource(Context context, @Nullable String source);
+  void setSource(Context context, @Nullable ReadableArray sources);
 
   /**
    * Assigns a tint color to apply to the image drawn.

ReactAndroid/src/main/java/com/facebook/react/flat/DrawImageWithDrawee.java

@@ -11,6 +11,9 @@ package com.facebook.react.flat;
 
 import javax.annotation.Nullable;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.PorterDuff;
@@ -23,6 +26,8 @@ import com.facebook.drawee.generic.GenericDraweeHierarchy;
 import com.facebook.drawee.generic.RoundingParams;
 import com.facebook.imagepipeline.request.ImageRequest;
 import com.facebook.infer.annotation.Assertions;
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.views.image.ImageLoadEvent;
 import com.facebook.react.views.image.ImageResizeMode;
 import com.facebook.react.views.image.ReactImageView;
@@ -34,7 +39,8 @@ import com.facebook.react.views.image.ReactImageView;
 /* package */ final class DrawImageWithDrawee extends AbstractDrawCommand
     implements DrawImage, ControllerListener {
 
-  private @Nullable String mSource;
+  private @Nullable Map<String, Double> mSources;
+  private @Nullable String mImageSource;
   private @Nullable Context mContext;
   private @Nullable DraweeRequestHelper mRequestHelper;
   private @Nullable PorterDuffColorFilter mColorFilter;
@@ -48,12 +54,28 @@ import com.facebook.react.views.image.ReactImageView;
 
   @Override
   public boolean hasImageRequest() {
-    return mSource != null;
+    return mSources != null && !mSources.isEmpty();
   }
 
   @Override
-  public void setSource(Context context, @Nullable String source) {
-    mSource = source;
+  public void setSource(Context context, @Nullable ReadableArray sources) {
+    if (mSources == null) {
+      mSources = new HashMap<>();
+    }
+    mSources.clear();
+    if (sources != null && sources.size() != 0) {
+      // Optimize for the case where we have just one uri, case in which we don't need the sizes
+      if (sources.size() == 1) {
+        mSources.put(sources.getMap(0).getString("uri"), 0.0d);
+      } else {
+        for (int idx = 0; idx < sources.size(); idx++) {
+          ReadableMap source = sources.getMap(idx);
+          mSources.put(
+              source.getString("uri"),
+              source.getDouble("width") * source.getDouble("height"));
+        }
+      }
+    }
     mContext = context;
   }
 
@@ -202,23 +224,36 @@ import com.facebook.react.views.image.ReactImageView;
   @Override
   protected void onBoundsChanged() {
     super.onBoundsChanged();
-    maybeComputeRequestHelper();
+    computeRequestHelper();
   }
 
-  private void maybeComputeRequestHelper() {
-    if (mRequestHelper != null) {
-      return;
-    }
-
-    if (mSource == null) {
+  private void computeRequestHelper() {
+    mImageSource = getSourceImage();
+    if (mImageSource == null) {
       mRequestHelper = null;
       return;
     }
     ImageRequest imageRequest =
-        ImageRequestHelper.createImageRequest(Assertions.assertNotNull(mContext), mSource);
+        ImageRequestHelper.createImageRequest(Assertions.assertNotNull(mContext),
+        mImageSource);
     mRequestHelper = new DraweeRequestHelper(Assertions.assertNotNull(imageRequest), this);
   }
 
+  private @Nullable String getSourceImage() {
+    if (mSources == null || mSources.isEmpty()) {
+      return null;
+    }
+    if (hasMultipleSources()) {
+      final double targetImageSize = (getRight() - getLeft()) * (getBottom() - getTop());
+      return MultiSourceImageHelper.getImageSourceFromMultipleSources(targetImageSize, mSources);
+    }
+    return mSources.keySet().iterator().next();
+  }
+
+  private boolean hasMultipleSources() {
+    return Assertions.assertNotNull(mSources).size() > 1;
+  }
+
   private boolean shouldDisplayBorder() {
     return mBorderColor != 0 || mBorderRadius >= 0.5f;
   }

ReactAndroid/src/main/java/com/facebook/react/flat/DrawImageWithPipeline.java

@@ -11,6 +11,9 @@ package com.facebook.react.flat;
 
 import javax.annotation.Nullable;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.BitmapShader;
@@ -25,6 +28,8 @@ import android.graphics.Shader;
 import com.facebook.drawee.drawable.ScalingUtils.ScaleType;
 import com.facebook.imagepipeline.request.ImageRequest;
 import com.facebook.infer.annotation.Assertions;
+import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.views.image.ImageResizeMode;
 import com.facebook.react.views.image.ReactImageView;
 
@@ -38,7 +43,8 @@ import com.facebook.react.views.image.ReactImageView;
   private static final Paint PAINT = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
   private static final int BORDER_BITMAP_PATH_DIRTY = 1 << 1;
 
-  private @Nullable String mSource;
+  private @Nullable Map<String, Double> mSources;
+  private @Nullable String mImageSource;
   private @Nullable Context mContext;
   private final Matrix mTransform = new Matrix();
   private ScaleType mScaleType = ImageResizeMode.defaultValue();
@@ -61,8 +67,24 @@ import com.facebook.react.views.image.ReactImageView;
   }
 
   @Override
-  public void setSource(Context context, @Nullable String source) {
-    mSource = source;
+  public void setSource(Context context, @Nullable ReadableArray sources) {
+    if (mSources == null) {
+      mSources = new HashMap<>();
+    }
+    mSources.clear();
+    if (sources != null && sources.size() != 0) {
+      // Optimize for the case where we have just one uri, case in which we don't need the sizes
+      if (sources.size() == 1) {
+        mSources.put(sources.getMap(0).getString("uri"), 0.0d);
+      } else {
+        for (int idx = 0; idx < sources.size(); idx++) {
+          ReadableMap source = sources.getMap(idx);
+          mSources.put(
+              source.getString("uri"),
+              source.getDouble("width") * source.getDouble("height"));
+        }
+      }
+    }
     mContext = context;
     mBitmapShader = null;
   }
@@ -183,7 +205,7 @@ import com.facebook.react.views.image.ReactImageView;
   protected void onBoundsChanged() {
     super.onBoundsChanged();
     setFlag(BORDER_BITMAP_PATH_DIRTY);
-    maybeComputeRequestHelper();
+    computeRequestHelper();
   }
 
   @Override
@@ -203,20 +225,33 @@ import com.facebook.react.views.image.ReactImageView;
     }
   }
 
-  private void maybeComputeRequestHelper() {
-    if (mRequestHelper == null) {
-      return;
-    }
-
-    if (mSource == null) {
+  private void computeRequestHelper() {
+    mImageSource = getSourceImage();
+    if (mImageSource == null) {
       mRequestHelper = null;
       return;
     }
     ImageRequest imageRequest =
-        ImageRequestHelper.createImageRequest(Assertions.assertNotNull(mContext), mSource);
+        ImageRequestHelper.createImageRequest(Assertions.assertNotNull(mContext),
+        mImageSource);
     mRequestHelper = new PipelineRequestHelper(Assertions.assertNotNull(imageRequest));
   }
 
+  private String getSourceImage() {
+    if (mSources == null || mSources.isEmpty()) {
+      return null;
+    }
+    if (hasMultipleSources()) {
+      final double targetImageSize = (getRight() - getLeft()) * (getBottom() - getTop());
+      return MultiSourceImageHelper.getImageSourceFromMultipleSources(targetImageSize, mSources);
+    }
+    return mSources.keySet().iterator().next();
+  }
+
+  private boolean hasMultipleSources() {
+    return Assertions.assertNotNull(mSources).size() > 1;
+  }
+
   /* package */ void updateBounds(Bitmap bitmap) {
     Assertions.assumeNotNull(mCallback).invalidate();
 

ReactAndroid/src/main/java/com/facebook/react/flat/MultiSourceImageHelper.java

@@ -0,0 +1,40 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.flat;
+
+import javax.annotation.Nullable;
+
+import java.util.Map;
+
+/**
+ * Helper class for computing the source to be used for an Image.
+ */
+/* package */ class MultiSourceImageHelper {
+
+  /**
+   * Chooses the image source with the size closest to the target image size. Must be called only
+   * after the layout pass when the sizes of the target image have been computed, and when there
+   * are at least two sources to choose from.
+   */
+  public static @Nullable String getImageSourceFromMultipleSources(
+      double targetImageSize,
+      Map<String, Double> sources) {
+    double bestPrecision = Double.MAX_VALUE;
+    String imageSource = null;
+    for (Map.Entry<String, Double> source : sources.entrySet()) {
+      final double precision = Math.abs(1.0 - (source.getValue()) / targetImageSize);
+      if (precision < bestPrecision) {
+        bestPrecision = precision;
+        imageSource = source.getKey();
+      }
+    }
+    return imageSource;
+  }
+}

ReactAndroid/src/main/java/com/facebook/react/flat/RCTImageView.java

@@ -88,9 +88,7 @@ import com.facebook.react.views.image.ImageResizeMode;
 
   @ReactProp(name = "src")
   public void setSource(@Nullable ReadableArray sources) {
-    final String source =
-        (sources == null || sources.size() == 0) ? null : sources.getMap(0).getString("uri");
-    getMutableDrawImage().setSource(getThemedContext(), source);
+    getMutableDrawImage().setSource(getThemedContext(), sources);
   }
 
   @ReactProp(name = "tintColor")