Fabric: ScrollView events

Summary: Note: Some features are not suported yet, e.g. event throttling.

Reviewed By: fkgozali

Differential Revision: D8082771

fbshipit-source-id: d60f6e9011283aeee7aff77dc9178e99f06deb5c

ReactCommon/fabric/scrollview/ScrollViewEventHandlers.cpp

@@ -0,0 +1,64 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "ScrollViewEventHandlers.h"
+
+namespace facebook {
+namespace react {
+
+void ScrollViewEventHandlers::onScroll(const ScrollViewMetrics &scrollViewMetrics) const {
+  dispatchScrollViewEvent("scroll", scrollViewMetrics);
+}
+
+void ScrollViewEventHandlers::onScrollBeginDrag(const ScrollViewMetrics &scrollViewMetrics) const {
+  dispatchScrollViewEvent("scrollBeginDrag", scrollViewMetrics);
+}
+
+void ScrollViewEventHandlers::onScrollEndDrag(const ScrollViewMetrics &scrollViewMetrics) const {
+  dispatchScrollViewEvent("scrollEndDrag", scrollViewMetrics);
+}
+
+void ScrollViewEventHandlers::onMomentumScrollBegin(const ScrollViewMetrics &scrollViewMetrics) const {
+  dispatchScrollViewEvent("momentumScrollBegin", scrollViewMetrics);
+}
+
+void ScrollViewEventHandlers::onMomentumScrollEnd(const ScrollViewMetrics &scrollViewMetrics) const {
+  dispatchScrollViewEvent("momentumScrollEnd", scrollViewMetrics);
+}
+
+void ScrollViewEventHandlers::dispatchScrollViewEvent(const std::string &name, const ScrollViewMetrics &scrollViewMetrics, const folly::dynamic &payload) const {
+  folly::dynamic compoundPayload = folly::dynamic::object();
+
+  compoundPayload["contentOffset"] = folly::dynamic::object
+    ("x", scrollViewMetrics.contentOffset.x)
+    ("y", scrollViewMetrics.contentOffset.y);
+
+  compoundPayload["contentInset"] = folly::dynamic::object
+    ("top", scrollViewMetrics.contentInset.top)
+    ("left", scrollViewMetrics.contentInset.left)
+    ("bottom", scrollViewMetrics.contentInset.bottom)
+    ("right", scrollViewMetrics.contentInset.right);
+
+  compoundPayload["contentSize"] = folly::dynamic::object
+    ("width", scrollViewMetrics.contentSize.width)
+    ("height", scrollViewMetrics.contentSize.height);
+
+  compoundPayload["layoutMeasurement"] = folly::dynamic::object
+    ("width", scrollViewMetrics.containerSize.width)
+    ("height", scrollViewMetrics.containerSize.height);
+
+  compoundPayload["zoomScale"] = scrollViewMetrics.zoomScale;
+
+  if (!payload.isNull()) {
+    compoundPayload.merge_patch(payload);
+  }
+
+  dispatchEvent(name, compoundPayload);
+}
+
+} // namespace react
+} // namespace facebook