Cleanup ReactHorizontalScrollView

Reviewed By: achen1

Differential Revision: D6693605

fbshipit-source-id: e58425b2a5b0bf75ffb41ef3ab6fa7ad46222531

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollView.java

@@ -16,6 +16,7 @@
 import android.graphics.Rect;
 import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
+import android.support.v4.view.ViewCompat;
 import android.view.MotionEvent;
 import android.view.View;
 import android.widget.HorizontalScrollView;
@@ -30,6 +31,7 @@
 /**
  * Similar to {@link ReactScrollView} but only supports horizontal scrolling.
  */
+@TargetApi(16)
 public class ReactHorizontalScrollView extends HorizontalScrollView implements
     ReactClippingViewGroup {
 
@@ -271,7 +273,6 @@ public void draw(Canvas canvas) {
    * don't get any events from Android about this lifecycle, we do all our detection by creating a
    * runnable that checks if we scrolled in the last frame and if so assumes we are still scrolling.
    */
-  @TargetApi(16)
   private void handlePostTouchScrolling(int velocityX, int velocityY) {
     // If we aren't going to do anything (send events or snap to page), we can early out.
     if (!mSendMomentumEvents && !mPagingEnabled && !isScrollPerfLoggingEnabled()) {
@@ -298,14 +299,18 @@ public void run() {
         if (mActivelyScrolling) {
           // We are still scrolling so we just post to check again a frame later
           mActivelyScrolling = false;
-          ReactHorizontalScrollView.this.postOnAnimationDelayed(this, ReactScrollViewHelper.MOMENTUM_DELAY);
+          ViewCompat.postOnAnimationDelayed(ReactHorizontalScrollView.this,
+            this,
+            ReactScrollViewHelper.MOMENTUM_DELAY);
         } else {
           if (mPagingEnabled && !mSnappingToPage) {
             // Only if we have pagingEnabled and we have not snapped to the page do we
             // need to continue checking for the scroll.  And we cause that scroll by asking for it
             mSnappingToPage = true;
             smoothScrollToPage(0);
-            ReactHorizontalScrollView.this.postOnAnimationDelayed(this, ReactScrollViewHelper.MOMENTUM_DELAY);
+            ViewCompat.postOnAnimationDelayed(ReactHorizontalScrollView.this,
+              this,
+              ReactScrollViewHelper.MOMENTUM_DELAY);
           } else {
             if (mSendMomentumEvents) {
               ReactScrollViewHelper.emitScrollMomentumEndEvent(ReactHorizontalScrollView.this);
@@ -316,7 +321,9 @@ public void run() {
         }
       }
     };
-    postOnAnimationDelayed(mPostTouchRunnable, ReactScrollViewHelper.MOMENTUM_DELAY);
+    ViewCompat.postOnAnimationDelayed(ReactHorizontalScrollView.this,
+      mPostTouchRunnable,
+      ReactScrollViewHelper.MOMENTUM_DELAY);
   }
 
   /**

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java

@@ -9,6 +9,7 @@
 
 package com.facebook.react.views.scroll;
 
+import android.annotation.TargetApi;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Rect;
@@ -39,13 +40,14 @@
  * <p>ReactScrollView only supports vertical scrolling. For horizontal scrolling,
  * use {@link ReactHorizontalScrollView}.
  */
+@TargetApi(11)
 public class ReactScrollView extends ScrollView implements ReactClippingViewGroup, ViewGroup.OnHierarchyChangeListener, View.OnLayoutChangeListener {
 
-  private static Field sScrollerField;
+  private static @Nullable Field sScrollerField;
   private static boolean sTriedToGetScrollerField = false;
 
   private final OnScrollDispatchHelper mOnScrollDispatchHelper = new OnScrollDispatchHelper();
-  private final OverScroller mScroller;
+  private final @Nullable OverScroller mScroller;
   private final VelocityHelper mVelocityHelper = new VelocityHelper();
 
   private @Nullable Rect mClippingRect;
@@ -71,6 +73,15 @@ public ReactScrollView(ReactContext context, @Nullable FpsListener fpsListener)
     mFpsListener = fpsListener;
     mReactBackgroundManager = new ReactViewBackgroundManager(this);
 
+    mScroller = getOverScrollerFromParent();
+    setOnHierarchyChangeListener(this);
+    setScrollBarStyle(SCROLLBARS_OUTSIDE_OVERLAY);
+  }
+
+  @Nullable
+  private OverScroller getOverScrollerFromParent() {
+    OverScroller scroller;
+
     if (!sTriedToGetScrollerField) {
       sTriedToGetScrollerField = true;
       try {
@@ -86,32 +97,31 @@ public ReactScrollView(ReactContext context, @Nullable FpsListener fpsListener)
 
     if (sScrollerField != null) {
       try {
-        Object scroller = sScrollerField.get(this);
-        if (scroller instanceof OverScroller) {
-          mScroller = (OverScroller) scroller;
+        Object scrollerValue = sScrollerField.get(this);
+        if (scrollerValue instanceof OverScroller) {
+          scroller = (OverScroller) scrollerValue;
         } else {
           Log.w(
             ReactConstants.TAG,
             "Failed to cast mScroller field in ScrollView (probably due to OEM changes to AOSP)! " +
               "This app will exhibit the bounce-back scrolling bug :(");
-          mScroller = null;
+          scroller = null;
         }
       } catch (IllegalAccessException e) {
         throw new RuntimeException("Failed to get mScroller from ScrollView!", e);
       }
     } else {
-      mScroller = null;
+      scroller = null;
     }
 
-    setOnHierarchyChangeListener(this);
-    setScrollBarStyle(SCROLLBARS_OUTSIDE_OVERLAY);
+    return scroller;
   }
 
   public void setSendMomentumEvents(boolean sendMomentumEvents) {
     mSendMomentumEvents = sendMomentumEvents;
   }
 
-  public void setScrollPerfTag(String scrollPerfTag) {
+  public void setScrollPerfTag(@Nullable String scrollPerfTag) {
     mScrollPerfTag = scrollPerfTag;
   }
 

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java

@@ -9,6 +9,7 @@
 
 package com.facebook.react.views.scroll;
 
+import android.annotation.TargetApi;
 import android.graphics.Color;
 import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.common.MapBuilder;
@@ -31,6 +32,7 @@
  * <p>Note that {@link ReactScrollView} and {@link ReactHorizontalScrollView} are exposed to JS
  * as a single ScrollView component, configured via the {@code horizontal} boolean property.
  */
+@TargetApi(11)
 @ReactModule(name = ReactScrollViewManager.REACT_CLASS)
 public class ReactScrollViewManager
     extends ViewGroupManager<ReactScrollView>
@@ -98,7 +100,7 @@ public void setSendMomentumEvents(ReactScrollView view, boolean sendMomentumEven
    * @param scrollPerfTag
    */
   @ReactProp(name = "scrollPerfTag")
-  public void setScrollPerfTag(ReactScrollView view, String scrollPerfTag) {
+  public void setScrollPerfTag(ReactScrollView view, @Nullable String scrollPerfTag) {
     view.setScrollPerfTag(scrollPerfTag);
   }
 
@@ -191,8 +193,8 @@ public void setBorderWidth(ReactScrollView view, int index, float width) {
   }, customType = "Color")
   public void setBorderColor(ReactScrollView view, int index, Integer color) {
     float rgbComponent =
-        color == null ? YogaConstants.UNDEFINED : (float) ((int)color & 0x00FFFFFF);
-    float alphaComponent = color == null ? YogaConstants.UNDEFINED : (float) ((int)color >>> 24);
+        color == null ? YogaConstants.UNDEFINED : (float) (color & 0x00FFFFFF);
+    float alphaComponent = color == null ? YogaConstants.UNDEFINED : (float) (color >>> 24);
     view.setBorderColor(SPACING_TYPES[index], rgbComponent, alphaComponent);
   }
 
@@ -211,12 +213,12 @@ public void scrollToEnd(
   }
 
   @Override
-  public @Nullable Map getExportedCustomDirectEventTypeConstants() {
+  public @Nullable Map<String, Object> getExportedCustomDirectEventTypeConstants() {
     return createExportedCustomDirectEventTypeConstants();
   }
 
-  public static Map createExportedCustomDirectEventTypeConstants() {
-    return MapBuilder.builder()
+  public static Map<String, Object> createExportedCustomDirectEventTypeConstants() {
+    return MapBuilder.<String, Object>builder()
         .put(ScrollEventType.SCROLL.getJSEventName(), MapBuilder.of("registrationName", "onScroll"))
         .put(ScrollEventType.BEGIN_DRAG.getJSEventName(), MapBuilder.of("registrationName", "onScrollBeginDrag"))
         .put(ScrollEventType.END_DRAG.getJSEventName(), MapBuilder.of("registrationName", "onScrollEndDrag"))