ReactSwipeRefreshLayout.java

/**
 * 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.swiperefresh;

import android.support.v4.widget.SwipeRefreshLayout;
import android.view.MotionEvent;
import android.view.ViewConfiguration;

import com.facebook.react.bridge.ReactContext;
import com.facebook.react.uimanager.PixelUtil;
import com.facebook.react.uimanager.events.NativeGestureUtil;

/**
 * Basic extension of {@link SwipeRefreshLayout} with ReactNative-specific functionality.
 */
public class ReactSwipeRefreshLayout extends SwipeRefreshLayout {

  private static final float DEFAULT_CIRCLE_TARGET = 64;

  private boolean mDidLayout = false;
  private boolean mRefreshing = false;
  private float mProgressViewOffset = 0;
  private int mTouchSlop;
  private float mPrevTouchX;
  private boolean mIntercepted;

  public ReactSwipeRefreshLayout(ReactContext reactContext) {
    super(reactContext);
    mTouchSlop = ViewConfiguration.get(reactContext).getScaledTouchSlop();
  }

  @Override
  public void setRefreshing(boolean refreshing) {
    mRefreshing = refreshing;

    // `setRefreshing` must be called after the initial layout otherwise it
    // doesn't work when mounting the component with `refreshing = true`.
    // Known Android issue: https://code.google.com/p/android/issues/detail?id=77712
    if (mDidLayout) {
      super.setRefreshing(refreshing);
    }
  }

  public void setProgressViewOffset(float offset) {
    mProgressViewOffset = offset;

    // The view must be measured before calling `getProgressCircleDiameter` so
    // don't do it before the initial layout.
    if (mDidLayout) {
      int diameter = getProgressCircleDiameter();
      int start = Math.round(PixelUtil.toPixelFromDIP(offset)) - diameter;
      int end = Math.round(PixelUtil.toPixelFromDIP(offset + DEFAULT_CIRCLE_TARGET) - diameter);
      setProgressViewOffset(false, start, end);
    }
  }

  @Override
  public void onLayout(boolean changed, int left, int top, int right, int bottom) {
    super.onLayout(changed, left, top, right, bottom);

    if (!mDidLayout) {
      mDidLayout = true;

      // Update values that must be set after initial layout.
      setProgressViewOffset(mProgressViewOffset);
      setRefreshing(mRefreshing);
    }
  }

  /**
   * {@link SwipeRefreshLayout} overrides {@link ViewGroup#requestDisallowInterceptTouchEvent} and
   * swallows it. This means that any component underneath SwipeRefreshLayout will now interact
   * incorrectly with Views that are above SwipeRefreshLayout. We fix that by transmitting the call
   * to this View's parents.
   */
  @Override
  public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
    if (getParent() != null) {
      getParent().requestDisallowInterceptTouchEvent(disallowIntercept);
    }
  }

  @Override
  public boolean onInterceptTouchEvent(MotionEvent ev) {
    if (shouldInterceptTouchEvent(ev) && super.onInterceptTouchEvent(ev)) {
      NativeGestureUtil.notifyNativeGestureStarted(this, ev);
      return true;
    }
    return false;
  }

  /**
   * {@link SwipeRefreshLayout} completely bypasses ViewGroup's "disallowIntercept" by overriding
   * {@link ViewGroup#onInterceptTouchEvent} and never calling super.onInterceptTouchEvent().
   * This means that horizontal scrolls will always be intercepted, even though they shouldn't, so
   * we have to check for that manually here.
   */
  private boolean shouldInterceptTouchEvent(MotionEvent ev) {
    switch (ev.getAction()) {
      case MotionEvent.ACTION_DOWN:
        mPrevTouchX = ev.getX();
        mIntercepted = false;
        break;

      case MotionEvent.ACTION_MOVE:
        final float eventX = ev.getX();
        final float xDiff = Math.abs(eventX - mPrevTouchX);

        if (mIntercepted || xDiff > mTouchSlop) {
          mIntercepted = true;
          return false;
        }
    }
    return true;
  }
}