extract MultiSourceHelper

Reviewed By: andreicoman11

Differential Revision: D3505224

fbshipit-source-id: e731325af7fd0c1cbd600695607302c968e0f36e

ReactAndroid/src/main/java/com/facebook/react/views/image/BUCK

@@ -9,7 +9,7 @@ android_library(
     react_native_target('java/com/facebook/csslayout:csslayout'),
     react_native_target('java/com/facebook/react/uimanager:uimanager'),
     react_native_target('java/com/facebook/react/uimanager/annotations:annotations'),
-    react_native_target('java/com/facebook/react/views/imagehelper:imagehelper'),
+    react_native_target('java/com/facebook/react/views/imagehelper:withmultisource'),
     react_native_dep('libraries/fresco/fresco-react-native:fbcore'),
     react_native_dep('libraries/fresco/fresco-react-native:fresco-react-native'),
     react_native_dep('libraries/fresco/fresco-react-native:fresco-drawee'),

ReactAndroid/src/main/java/com/facebook/react/views/image/ReactImageView.java

@@ -43,8 +43,6 @@ import com.facebook.drawee.generic.GenericDraweeHierarchyBuilder;
 import com.facebook.drawee.generic.RoundingParams;
 import com.facebook.drawee.view.GenericDraweeView;
 import com.facebook.imagepipeline.common.ResizeOptions;
-import com.facebook.imagepipeline.core.ImagePipeline;
-import com.facebook.imagepipeline.core.ImagePipelineFactory;
 import com.facebook.imagepipeline.image.ImageInfo;
 import com.facebook.imagepipeline.request.BasePostprocessor;
 import com.facebook.imagepipeline.request.ImageRequest;
@@ -58,7 +56,9 @@ import com.facebook.react.uimanager.PixelUtil;
 import com.facebook.react.uimanager.UIManagerModule;
 import com.facebook.react.uimanager.events.EventDispatcher;
 import com.facebook.react.views.imagehelper.ImageSource;
+import com.facebook.react.views.imagehelper.MultiSourceHelper;
 import com.facebook.react.views.imagehelper.ResourceDrawableIdHelper;
+import com.facebook.react.views.imagehelper.MultiSourceHelper.MultiSourceResult;
 
 /**
  * Wrapper class around Fresco's GenericDraweeView, enabling persisting props across multiple view
@@ -441,45 +441,16 @@ public class ReactImageView extends GenericDraweeView {
       return;
     }
     if (hasMultipleSources()) {
-      setImageSourceFromMultipleSources();
+      MultiSourceResult multiSource =
+        MultiSourceHelper.getBestSourceForSize(getWidth(), getHeight(), mSources);
+      mImageSource = multiSource.getBestResult();
+      mCachedImageSource = multiSource.getBestResultInCache();
       return;
     }
 
     mImageSource = mSources.get(0);
   }
 
-  /**
-   * 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.
-   */
-  private void setImageSourceFromMultipleSources() {
-    ImagePipeline imagePipeline = ImagePipelineFactory.getInstance().getImagePipeline();
-    final double targetImageSize = getWidth() * getHeight();
-    double bestPrecision = Double.MAX_VALUE;
-    double bestCachePrecision = Double.MAX_VALUE;
-    for (ImageSource source : mSources) {
-      final double precision = Math.abs(1.0 - (source.getSize()) / targetImageSize);
-      if (precision < bestPrecision) {
-        bestPrecision = precision;
-        mImageSource = source;
-      }
-
-      if (precision < bestCachePrecision &&
-          (imagePipeline.isInBitmapMemoryCache(source.getUri()) ||
-          imagePipeline.isInDiskCacheSync(source.getUri()))) {
-        bestCachePrecision = precision;
-        mCachedImageSource = source;
-      }
-    }
-
-    // don't use cached image source if it's the same as the image source
-    if (mCachedImageSource != null &&
-      mImageSource.getSource().equals(mCachedImageSource.getSource())) {
-      mCachedImageSource = null;
-    }
-  }
-
   private static boolean shouldResize(ImageSource imageSource) {
     // Resizing is inferior to scaling. See http://frescolib.org/docs/resizing-rotating.html#_
     // We resize here only for images likely to be from the device's camera, where the app developer

ReactAndroid/src/main/java/com/facebook/react/views/imagehelper/BUCK

@@ -2,7 +2,7 @@ include_defs('//ReactAndroid/DEFS')
 
 android_library(
   name = 'imagehelper',
-  srcs = glob(['*.java']),
+  srcs = glob(['*.java'], excludes=['MultiSourceHelper.java']),
   deps = [
     react_native_dep('third-party/java/infer-annotations:infer-annotations'),
     react_native_dep('third-party/java/jsr-305:jsr-305'),
@@ -12,6 +12,22 @@ android_library(
   ],
 )
 
+android_library(
+  name = 'withmultisource',
+  srcs = ['MultiSourceHelper.java'],
+  exported_deps = [
+    ':imagehelper',
+  ],
+  deps = [
+    react_native_dep('libraries/fresco/fresco-react-native:imagepipeline'),
+    react_native_dep('third-party/java/infer-annotations:infer-annotations'),
+    react_native_dep('third-party/java/jsr-305:jsr-305'),
+  ],
+  visibility = [
+    'PUBLIC',
+  ],
+)
+
 project_config(
   src_target = ':imagehelper',
 )

ReactAndroid/src/main/java/com/facebook/react/views/imagehelper/MultiSourceHelper.java

@@ -0,0 +1,105 @@
+/**
+ * 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.views.imagehelper;
+
+import javax.annotation.Nullable;
+
+import java.util.List;
+
+import com.facebook.imagepipeline.core.ImagePipeline;
+import com.facebook.imagepipeline.core.ImagePipelineFactory;
+import com.facebook.react.views.imagehelper.ImageSource;
+
+/**
+ * Helper class for dealing with multisource images.
+ */
+public class MultiSourceHelper {
+
+  public static class MultiSourceResult {
+    private final @Nullable ImageSource bestResult;
+    private final @Nullable ImageSource bestResultInCache;
+
+    private MultiSourceResult(
+      @Nullable ImageSource bestResult,
+      @Nullable ImageSource bestResultInCache) {
+      this.bestResult = bestResult;
+      this.bestResultInCache = bestResultInCache;
+    }
+
+    /**
+     * Get the best result overall (closest in size to the view's size). Can be null if there were
+     * no sources to choose from, or if there were more than 1 sources but width/height were 0.
+     */
+    public @Nullable ImageSource getBestResult() {
+      return bestResult;
+    }
+
+    /**
+     * Get the best result (closest in size to the view's size) that is also in cache. If this would
+     * be the same as the source from {@link #getBestResult()}, this will return {@code null}
+     * instead.
+     */
+    public @Nullable ImageSource getBestResultInCache() {
+      return bestResultInCache;
+    }
+  }
+
+  /**
+   * Chooses the image source with the size closest to the target image size.
+   *
+   * @param width the width of the view that will be used to display this image
+   * @param height the height of the view that will be used to display this image
+   * @param sources the list of potential image sources to choose from
+   */
+  public static MultiSourceResult getBestSourceForSize(
+    int width,
+    int height,
+    List<ImageSource> sources) {
+    // no sources
+    if (sources.isEmpty()) {
+      return new MultiSourceResult(null, null);
+    }
+
+    // single source
+    if (sources.size() == 1) {
+      return new MultiSourceResult(sources.get(0), null);
+    }
+
+    // For multiple sources, we first need the view's size in order to determine the best source to
+    // load. If we haven't been measured yet, return null and wait for onSizeChanged.
+    if (width <= 0 || height <= 0) {
+      return new MultiSourceResult(null, null);
+    }
+
+    ImagePipeline imagePipeline = ImagePipelineFactory.getInstance().getImagePipeline();
+    ImageSource best = null;
+    ImageSource bestCached = null;
+    final double viewArea = width * height;
+    double bestPrecision = Double.MAX_VALUE;
+    double bestCachePrecision = Double.MAX_VALUE;
+    for (ImageSource source : sources) {
+      double precision = Math.abs(1.0 - source.getSize() / viewArea);
+      if (precision < bestPrecision) {
+        bestPrecision = precision;
+        best = source;
+      }
+      if (precision < bestCachePrecision &&
+        (imagePipeline.isInBitmapMemoryCache(source.getUri()) ||
+          imagePipeline.isInDiskCacheSync(source.getUri()))) {
+        bestCachePrecision = precision;
+        bestCached = source;
+      }
+    }
+    if (bestCached != null && best != null && bestCached.getSource().equals(best.getSource())) {
+      bestCached = null;
+    }
+    return new MultiSourceResult(best, bestCached);
+  }
+}