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A framework for building native apps with React
/**
* 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.viewpager;
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 {@link ReactViewPager} when user scrolls between pages (or when animating
* between pages).
*
* Additional data provided by this event:
* - position - index of first page from the left that is currently visible
* - offset - value from range [0,1) describing stage between page transitions. Value x means that
* (1 - x) fraction of the page at "position" index is visible, and x fraction of the next page
* is visible.
*/
/* package */ class PageScrollEvent extends Event {
public static final String EVENT_NAME = "topPageScroll";
private final int mPosition;
private final float mOffset;
protected PageScrollEvent(int viewTag, int position, float offset) {
super(viewTag);
mPosition = position;
// folly::toJson default options don't support serialize NaN or Infinite value
mOffset = (Float.isInfinite(offset) || Float.isNaN(offset))
? 0.0f : offset;
}
@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();
eventData.putInt("position", mPosition);
eventData.putDouble("offset", mOffset);
return eventData;
}
}