Initial attempt at fixing issue facebook#23870 by overriding getChildVisibleRect() in ReactViewGroup

Author: davidbiedenbach

ReactAndroid/src/main/java/com/facebook/react/views/view/ReactViewGroup.java

@@ -21,6 +21,7 @@
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup;
+import android.view.ViewParent;
 import android.view.ViewStructure;
 import android.view.animation.Animation;
 import com.facebook.common.logging.FLog;
@@ -427,6 +428,53 @@ private void updateSubviewClipStatus(View subview) {
     }
   }
 
+  @Override
+  public boolean getChildVisibleRect(View child, Rect r, android.graphics.Point offset) {
+    // This is based on the Android ViewGroup implementation, modified to clip child rects
+    // if overflow is set to ViewProps.HIDDEN. This effectively solves Issue #23870 which
+    // appears to have been introduced by FLAG_CLIP_CHILDREN being forced false
+    // regardless of whether clipping is desired.
+
+    final RectF rect = new RectF();
+    rect.set(r);
+
+    child.getMatrix().mapRect(rect);
+
+    final int dx = child.getLeft() - getScrollX();
+    int dy = child.getTop() - getScrollY();
+
+    rect.offset(dx, dy);
+
+    if (offset != null) {
+      float[] position = new float[2];
+      position[0] = offset.x;
+      position[1] = offset.y;
+      child.getMatrix().mapPoints(position);
+      offset.x = Math.round(position[0]) + dx;
+      offset.y = Math.round(position[1]) + dy;
+    }
+
+    final int width = getRight() - getLeft();
+    final int height = getBottom() - getTop();
+
+    boolean rectIsVisible = true;
+
+    ViewParent parent = getParent();
+    String overflow = getOverflow();
+    if (parent == null ||
+      (overflow != null && overflow.equals(ViewProps.HIDDEN))) {
+      rectIsVisible = rect.intersect(0, 0, width, height);
+    }
+
+    r.set((int) Math.floor(rect.left), (int) Math.floor(rect.top),
+      (int) Math.ceil(rect.right), (int) Math.ceil(rect.bottom));
+
+    if (rectIsVisible && parent != null) {
+      rectIsVisible = parent.getChildVisibleRect(this, r, offset);
+    }
+    return rectIsVisible;
+  }
+
   @Override
   protected void onSizeChanged(int w, int h, int oldw, int oldh) {
     super.onSizeChanged(w, h, oldw, oldh);