Add "contentOffset" property to ScrollView

Author: dmitryn

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

@@ -33,8 +33,10 @@
 
 import java.lang.reflect.Field;
 import java.util.List;
+import java.util.HashMap;
 import javax.annotation.Nullable;
 
+
 /**
  * A simple subclass of ScrollView that doesn't dispatch measure and layout to its children and has
  * a scroll listener to send scroll events to JS.
@@ -71,6 +73,7 @@ public class ReactScrollView extends ScrollView implements ReactClippingViewGrou
   private @Nullable List<Integer> mSnapOffsets;
   private View mContentView;
   private ReactViewBackgroundManager mReactBackgroundManager;
+  private HashMap<String, Integer> mContentOffset = null;
 
   public ReactScrollView(ReactContext context) {
     this(context, null);
@@ -175,10 +178,20 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         MeasureSpec.getSize(heightMeasureSpec));
   }
 
+  public void setContentOffset(HashMap<String, Integer> contentOffset) {
+    mContentOffset = contentOffset;
+  }
+
   @Override
   protected void onLayout(boolean changed, int l, int t, int r, int b) {
     // Call with the present values in order to re-layout if necessary
-    scrollTo(getScrollX(), getScrollY());
+    // If contentOffset is set scroll to its position
+    if (mContentOffset != null) {
+      scrollTo(mContentOffset.get("x"), mContentOffset.get("y"));
+    } else {
+      // Call with the present values in order to re-layout if necessary
+      scrollTo(getScrollX(), getScrollY());
+    }
   }
 
   @Override

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

@@ -13,6 +13,7 @@
 import android.util.DisplayMetrics;
 
 import com.facebook.react.bridge.ReadableArray;
+import com.facebook.react.bridge.ReadableMap;
 import com.facebook.react.common.MapBuilder;
 import com.facebook.react.module.annotations.ReactModule;
 import com.facebook.react.uimanager.DisplayMetricsHolder;
@@ -28,6 +29,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.HashMap;
 import java.util.Map;
 import javax.annotation.Nullable;
 
@@ -211,6 +213,25 @@ public void setBorderStyle(ReactScrollView view, @Nullable String borderStyle) {
     view.setBorderStyle(borderStyle);
   }
 
+  /**
+   * When set, the scrollview will scroll to the given position on initial layout
+   * @param view
+   * @param contentOffset
+   */
+  @ReactProp(name = "contentOffset")
+  public void setContentOffset(ReactScrollView view, ReadableMap contentOffset) {
+    if (!contentOffset.hasKey("x") || !contentOffset.hasKey("y")) {
+      return;
+    }
+    int destX = Math.round(PixelUtil.toPixelFromDIP(contentOffset.getDouble("x")));
+    int destY = Math.round(PixelUtil.toPixelFromDIP(contentOffset.getDouble("y")));
+
+    HashMap<String, Integer> initialOffset = new HashMap<String, Integer>();
+    initialOffset.put("x", destX);
+    initialOffset.put("y", destY);
+    view.setContentOffset(initialOffset);
+  }
+
   @ReactPropGroup(names = {
       ViewProps.BORDER_WIDTH,
       ViewProps.BORDER_LEFT_WIDTH,