Add onSelectionChange for Android TextInput

Summary:
public

Add an onSelectionChange method to TextInput that works on Android same as iOS

Reviewed By: andreicoman11

Differential Revision: D2780131

fb-gh-sync-id: 9b3b8fbd9ea653d43e3107a338e4bc08bde2e8c6

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactEditText.java

@@ -64,6 +64,7 @@ public class ReactEditText extends EditText {
   private @Nullable TextWatcherDelegator mTextWatcherDelegator;
   private int mStagedInputType;
   private boolean mContainsImages;
+  private @Nullable SelectionWatcher mSelectionWatcher;
 
   public ReactEditText(Context context) {
     super(context);
@@ -150,6 +151,27 @@ public class ReactEditText extends EditText {
     }
   }
 
+  @Override
+  protected void onSelectionChanged(int selStart, int selEnd) {
+    super.onSelectionChanged(selStart, selEnd);
+    if (mSelectionWatcher != null && hasFocus()) {
+      mSelectionWatcher.onSelectionChanged(selStart, selEnd);
+    }
+  }
+
+  @Override
+  protected void onFocusChanged(
+      boolean focused, int direction, Rect previouslyFocusedRect) {
+    super.onFocusChanged(focused, direction, previouslyFocusedRect);
+    if (focused && mSelectionWatcher != null) {
+      mSelectionWatcher.onSelectionChanged(getSelectionStart(), getSelectionEnd());
+    }
+  }
+
+  public void setSelectionWatcher(SelectionWatcher selectionWatcher) {
+    mSelectionWatcher = selectionWatcher;
+  }
+
   /*protected*/ int getStagedInputType() {
     return mStagedInputType;
   }
@@ -170,7 +192,8 @@ public class ReactEditText extends EditText {
     mStagedInputType = type;
   }
 
-  /* package */ void requestFocusFromJS() {
+  // VisibleForTesting from {@link TextInputEventsTestCase}.
+  public void requestFocusFromJS() {
     mIsJSSettingFocus = true;
     requestFocus();
     mIsJSSettingFocus = false;

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java

@@ -166,6 +166,15 @@ public class ReactTextInputManager extends
         (int) Math.ceil(PixelUtil.toPixelFromSP(fontSize)));
   }
 
+  @ReactProp(name = "onSelectionChange", defaultBoolean = false)
+  public void setOnSelectionChange(final ReactEditText view, boolean onSelectionChange) {
+    if (onSelectionChange) {
+      view.setSelectionWatcher(new ReactSelectionWatcher(view));
+    } else {
+      view.setSelectionWatcher(null);
+    }
+  }
+
   @ReactProp(name = "placeholder")
   public void setPlaceholder(ReactEditText view, @Nullable String placeholder) {
     view.setHint(placeholder);
@@ -418,6 +427,40 @@ public class ReactTextInputManager extends
         });
   }
 
+  private class ReactSelectionWatcher implements SelectionWatcher {
+
+    private ReactEditText mReactEditText;
+    private EventDispatcher mEventDispatcher;
+    private int mPreviousSelectionStart;
+    private int mPreviousSelectionEnd;
+
+    public ReactSelectionWatcher(ReactEditText editText) {
+      mReactEditText = editText;
+      ReactContext reactContext = (ReactContext) editText.getContext();
+      mEventDispatcher = reactContext.getNativeModule(UIManagerModule.class).getEventDispatcher();
+    }
+
+    @Override
+    public void onSelectionChanged(int start, int end) {
+      // Android will call us back for both the SELECTION_START span and SELECTION_END span in text
+      // To prevent double calling back into js we cache the result of the previous call and only
+      // forward it on if we have new values
+      if (mPreviousSelectionStart != start || mPreviousSelectionEnd != end) {
+        mEventDispatcher.dispatchEvent(
+            new ReactTextInputSelectionEvent(
+                mReactEditText.getId(),
+                SystemClock.uptimeMillis(),
+                start,
+                end
+            )
+        );
+
+        mPreviousSelectionStart = start;
+        mPreviousSelectionEnd = end;
+      }
+    }
+  }
+
   @Override
   public @Nullable Map getExportedViewConstants() {
     return MapBuilder.of(

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputSelectionEvent.java

@@ -0,0 +1,58 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.views.textinput;
+
+import com.facebook.react.bridge.Arguments;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.uimanager.events.Event;
+import com.facebook.react.uimanager.events.RCTEventEmitter;
+
+/**
+ * Event emitted by EditText native view when the text selection changes.
+ */
+/* package */ class ReactTextInputSelectionEvent
+    extends Event<ReactTextInputSelectionEvent> {
+
+  private static final String EVENT_NAME = "topSelectionChange";
+
+  private int mSelectionStart;
+  private int mSelectionEnd;
+
+  public ReactTextInputSelectionEvent(
+      int viewId,
+      long timestampMs,
+      int selectionStart,
+      int selectionEnd) {
+    super(viewId, timestampMs);
+    mSelectionStart = selectionStart;
+    mSelectionEnd = selectionEnd;
+  }
+
+  @Override
+  public String getEventName() {
+    return EVENT_NAME;
+  }
+
+  @Override
+  public void dispatch(RCTEventEmitter rctEventEmitter) {
+    rctEventEmitter.receiveEvent(getViewTag(), getEventName(), serializeEventData());
+  }
+
+  private WritableMap serializeEventData() {
+    WritableMap eventData = Arguments.createMap();
+
+    WritableMap selectionData = Arguments.createMap();
+    selectionData.putInt("start", mSelectionStart);
+    selectionData.putInt("end", mSelectionEnd);
+
+    eventData.putMap("selection", selectionData);
+    return eventData;
+  }
+}

ReactAndroid/src/main/java/com/facebook/react/views/textinput/SelectionWatcher.java

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.views.textinput;
+
+/**
+ * Implement this interface to be informed of selection changes in the ReactTextEdit
+ * This is used by the ReactTextInputManager to forward events from the EditText to JS
+ */
+interface SelectionWatcher {
+  public void onSelectionChanged(int start, int end);
+}