From 8a118f287c36dcb5ebbaad69709c454ab9dfff60 Mon Sep 17 00:00:00 2001
From: Jonas Lundberg <jonasl@catchmecode.com>
Date: Wed, 16 Aug 2017 11:02:15 +0200
Subject: [PATCH] Add vertical ScrollView content offset on Android

This is the (evil) twin commit to:
https://github.com/facebook/react-native/pull/12502

Fixes that contentOffset is not available on
Vertical scroll-views.

Verification:
* Create an Android component with a ScrollView. Add enough
  items to fill beyond the visible screen. Set the content
  offset to some value that makes the content scroll. Verify
  that it snaps to the y-axis as expected.
* Remove items so screen is no longer filled, keep content
  offset parameter. Scroll view still works but does not scroll.
* Set only one parameter to content-offset (x || y) -
  parameters are now ignored since they must be a pair.
* Remove contentOffset, scrollView still works as before.
---
 .../react/views/scroll/ReactScrollView.java   | 15 ++++++++++++-
 .../views/scroll/ReactScrollViewManager.java  | 21 +++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java
index 1336a63125937c..7de7f58f228d28 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java
@@ -12,6 +12,7 @@
 import javax.annotation.Nullable;
 
 import java.lang.reflect.Field;
+import java.util.HashMap;
 
 import android.graphics.Canvas;
 import android.graphics.Color;
@@ -64,6 +65,7 @@ public class ReactScrollView extends ScrollView implements ReactClippingViewGrou
   private int mEndFillColor = Color.TRANSPARENT;
   private View mContentView;
   private @Nullable ReactViewBackgroundDrawable mReactBackgroundDrawable;
+  private HashMap<String, Integer> mContentOffset = null;
 
   public ReactScrollView(ReactContext context) {
     this(context, null);
@@ -130,10 +132,21 @@ 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
diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java
index f110330b5708f0..50c901716ab673 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java
@@ -11,12 +11,14 @@
 
 import javax.annotation.Nullable;
 
+import java.util.HashMap;
 import java.util.Map;
 
 import android.graphics.Color;
 import android.view.View;
 
 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.PixelUtil;
@@ -172,6 +174,25 @@ 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,