Android Open Source - Android-PullToRefresh-master Overscroll Helper






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Java Source Code

/*******************************************************************************
 * Copyright 2011, 2012 Chris Banes.//from w w w .j  a v  a 2  s  . c o m
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.handmark.pulltorefresh.library;

import android.annotation.TargetApi;
import android.util.Log;
import android.view.View;

import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
import com.handmark.pulltorefresh.library.PullToRefreshBase.State;

@TargetApi(9)
public final class OverscrollHelper {

  static final String LOG_TAG = "OverscrollHelper";
  static final float DEFAULT_OVERSCROLL_SCALE = 1f;

  /**
   * Helper method for Overscrolling that encapsulates all of the necessary
   * function.
   * <p/>
   * This should only be used on AdapterView's such as ListView as it just
   * calls through to overScrollBy() with the scrollRange = 0. AdapterView's
   * do not have a scroll range (i.e. getScrollY() doesn't work).
   * 
   * @param view - PullToRefreshView that is calling this.
   * @param deltaX - Change in X in pixels, passed through from from
   *            overScrollBy call
   * @param scrollX - Current X scroll value in pixels before applying deltaY,
   *            passed through from from overScrollBy call
   * @param deltaY - Change in Y in pixels, passed through from from
   *            overScrollBy call
   * @param scrollY - Current Y scroll value in pixels before applying deltaY,
   *            passed through from from overScrollBy call
   * @param isTouchEvent - true if this scroll operation is the result of a
   *            touch event, passed through from from overScrollBy call
   */
  public static void overScrollBy(final PullToRefreshBase<?> view, final int deltaX, final int scrollX,
      final int deltaY, final int scrollY, final boolean isTouchEvent) {
    overScrollBy(view, deltaX, scrollX, deltaY, scrollY, 0, isTouchEvent);
  }

  /**
   * Helper method for Overscrolling that encapsulates all of the necessary
   * function. This version of the call is used for Views that need to specify
   * a Scroll Range but scroll back to it's edge correctly.
   * 
   * @param view - PullToRefreshView that is calling this.
   * @param deltaX - Change in X in pixels, passed through from from
   *            overScrollBy call
   * @param scrollX - Current X scroll value in pixels before applying deltaY,
   *            passed through from from overScrollBy call
   * @param deltaY - Change in Y in pixels, passed through from from
   *            overScrollBy call
   * @param scrollY - Current Y scroll value in pixels before applying deltaY,
   *            passed through from from overScrollBy call
   * @param scrollRange - Scroll Range of the View, specifically needed for
   *            ScrollView
   * @param isTouchEvent - true if this scroll operation is the result of a
   *            touch event, passed through from from overScrollBy call
   */
  public static void overScrollBy(final PullToRefreshBase<?> view, final int deltaX, final int scrollX,
      final int deltaY, final int scrollY, final int scrollRange, final boolean isTouchEvent) {
    overScrollBy(view, deltaX, scrollX, deltaY, scrollY, scrollRange, 0, DEFAULT_OVERSCROLL_SCALE, isTouchEvent);
  }

  /**
   * Helper method for Overscrolling that encapsulates all of the necessary
   * function. This is the advanced version of the call.
   * 
   * @param view - PullToRefreshView that is calling this.
   * @param deltaX - Change in X in pixels, passed through from from
   *            overScrollBy call
   * @param scrollX - Current X scroll value in pixels before applying deltaY,
   *            passed through from from overScrollBy call
   * @param deltaY - Change in Y in pixels, passed through from from
   *            overScrollBy call
   * @param scrollY - Current Y scroll value in pixels before applying deltaY,
   *            passed through from from overScrollBy call
   * @param scrollRange - Scroll Range of the View, specifically needed for
   *            ScrollView
   * @param fuzzyThreshold - Threshold for which the values how fuzzy we
   *            should treat the other values. Needed for WebView as it
   *            doesn't always scroll back to it's edge. 0 = no fuzziness.
   * @param scaleFactor - Scale Factor for overscroll amount
   * @param isTouchEvent - true if this scroll operation is the result of a
   *            touch event, passed through from from overScrollBy call
   */
  public static void overScrollBy(final PullToRefreshBase<?> view, final int deltaX, final int scrollX,
      final int deltaY, final int scrollY, final int scrollRange, final int fuzzyThreshold,
      final float scaleFactor, final boolean isTouchEvent) {

    final int deltaValue, currentScrollValue, scrollValue;
    switch (view.getPullToRefreshScrollDirection()) {
      case HORIZONTAL:
        deltaValue = deltaX;
        scrollValue = scrollX;
        currentScrollValue = view.getScrollX();
        break;
      case VERTICAL:
      default:
        deltaValue = deltaY;
        scrollValue = scrollY;
        currentScrollValue = view.getScrollY();
        break;
    }

    // Check that OverScroll is enabled and that we're not currently
    // refreshing.
    if (view.isPullToRefreshOverScrollEnabled() && !view.isRefreshing()) {
      final Mode mode = view.getMode();

      // Check that Pull-to-Refresh is enabled, and the event isn't from
      // touch
      if (mode.permitsPullToRefresh() && !isTouchEvent && deltaValue != 0) {
        final int newScrollValue = (deltaValue + scrollValue);

        if (PullToRefreshBase.DEBUG) {
          Log.d(LOG_TAG, "OverScroll. DeltaX: " + deltaX + ", ScrollX: " + scrollX + ", DeltaY: " + deltaY
              + ", ScrollY: " + scrollY + ", NewY: " + newScrollValue + ", ScrollRange: " + scrollRange
              + ", CurrentScroll: " + currentScrollValue);
        }

        if (newScrollValue < (0 - fuzzyThreshold)) {
          // Check the mode supports the overscroll direction, and
          // then move scroll
          if (mode.showHeaderLoadingLayout()) {
            // If we're currently at zero, we're about to start
            // overscrolling, so change the state
            if (currentScrollValue == 0) {
              view.setState(State.OVERSCROLLING);
            }

            view.setHeaderScroll((int) (scaleFactor * (currentScrollValue + newScrollValue)));
          }
        } else if (newScrollValue > (scrollRange + fuzzyThreshold)) {
          // Check the mode supports the overscroll direction, and
          // then move scroll
          if (mode.showFooterLoadingLayout()) {
            // If we're currently at zero, we're about to start
            // overscrolling, so change the state
            if (currentScrollValue == 0) {
              view.setState(State.OVERSCROLLING);
            }

            view.setHeaderScroll((int) (scaleFactor * (currentScrollValue + newScrollValue - scrollRange)));
          }
        } else if (Math.abs(newScrollValue) <= fuzzyThreshold
            || Math.abs(newScrollValue - scrollRange) <= fuzzyThreshold) {
          // Means we've stopped overscrolling, so scroll back to 0
          view.setState(State.RESET);
        }
      } else if (isTouchEvent && State.OVERSCROLLING == view.getState()) {
        // This condition means that we were overscrolling from a fling,
        // but the user has touched the View and is now overscrolling
        // from touch instead. We need to just reset.
        view.setState(State.RESET);
      }
    }
  }

  static boolean isAndroidOverScrollEnabled(View view) {
    return view.getOverScrollMode() != View.OVER_SCROLL_NEVER;
  }
}




Java Source Code List

com.handmark.pulltorefresh.library.ILoadingLayout.java
com.handmark.pulltorefresh.library.IPullToRefresh.java
com.handmark.pulltorefresh.library.LoadingLayoutProxy.java
com.handmark.pulltorefresh.library.OverscrollHelper.java
com.handmark.pulltorefresh.library.PullToRefreshAdapterViewBase.java
com.handmark.pulltorefresh.library.PullToRefreshBase.java
com.handmark.pulltorefresh.library.PullToRefreshExpandableListView.java
com.handmark.pulltorefresh.library.PullToRefreshGridView.java
com.handmark.pulltorefresh.library.PullToRefreshHorizontalScrollView.java
com.handmark.pulltorefresh.library.PullToRefreshListView.java
com.handmark.pulltorefresh.library.PullToRefreshScrollView.java
com.handmark.pulltorefresh.library.PullToRefreshWebView.java
com.handmark.pulltorefresh.library.extras.PullToRefreshWebView2.java
com.handmark.pulltorefresh.library.extras.SoundPullEventListener.java
com.handmark.pulltorefresh.library.internal.EmptyViewMethodAccessor.java
com.handmark.pulltorefresh.library.internal.FlipLoadingLayout.java
com.handmark.pulltorefresh.library.internal.IndicatorLayout.java
com.handmark.pulltorefresh.library.internal.LoadingLayout.java
com.handmark.pulltorefresh.library.internal.RotateLoadingLayout.java
com.handmark.pulltorefresh.library.internal.Utils.java
com.handmark.pulltorefresh.library.internal.ViewCompat.java