Java Code Examples for androidx.recyclerview.widget.OrientationHelper#getDecoratedStart()

private View findFirstView(RecyclerView.LayoutManager layoutManager, OrientationHelper helper) {
  if (layoutManager == null) return null;

  int childCount = layoutManager.getChildCount();
  if (childCount == 0) return null;

  int absClosest = Integer.MAX_VALUE;
  View closestView = null;
  int start = helper.getStartAfterPadding();

  for (int i=0; i < childCount; i++) {
    View child = layoutManager.getChildAt(i);
    int childStart = helper.getDecoratedStart(child);
    int absDistanceToStart = Math.abs(childStart - start);
    if (absDistanceToStart < absClosest) {
      absClosest = absDistanceToStart;
      closestView = child;
    }
  }

  return closestView;
}
 

/** @return the first View whose start is before the start of this recycler view */
@Nullable
private static View findFirstViewBeforeStart(
    LayoutManager layoutManager, OrientationHelper helper) {
  int childCount = layoutManager.getChildCount();
  if (childCount == 0) {
    return null;
  }

  View closestChild = null;
  final int start = helper.getStartAfterPadding();
  int absClosest = Integer.MAX_VALUE;

  for (int i = 0; i < childCount; i++) {
    final View child = layoutManager.getChildAt(i);
    int childStart = helper.getDecoratedStart(child);
    int absDistance = Math.abs(childStart - start);

    if (childStart < start && absDistance < absClosest) {
      absClosest = absDistance;
      closestChild = child;
    }
  }

  return closestChild;
}
 

private int distanceToStart(View targetView, OrientationHelper helper, boolean fromEnd) {
    if (isRtlHorizontal && !fromEnd) {
        return distanceToEnd(targetView, helper, true);
    }

    return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
}
 

private int distanceToStart(
    @NonNull RecyclerView.LayoutManager layoutManager,
    @NonNull View targetView,
    OrientationHelper helper) {
  final int childStart = helper.getDecoratedStart(targetView);
  final int containerStart = helper.getStartAfterPadding();
  return childStart - containerStart;
}
 

/**
 * Return the child view that is currently closest to the start of this parent.
 *
 * @param layoutManager The {@link LayoutManager} associated with the attached {@link
 *     RecyclerView}.
 * @param helper The relevant {@link OrientationHelper} for the attached {@link RecyclerView}.
 * @return the child view that is currently closest to the start of this parent.
 */
@Nullable
private static View findViewClosestToStart(
    LayoutManager layoutManager, OrientationHelper helper) {
  int childCount = layoutManager.getChildCount();
  if (childCount == 0) {
    return null;
  }

  View closestChild = null;
  final int start = helper.getStartAfterPadding();
  int absClosest = Integer.MAX_VALUE;

  for (int i = 0; i < childCount; i++) {
    final View child = layoutManager.getChildAt(i);
    int childStart = helper.getDecoratedStart(child);
    int absDistance = Math.abs(childStart - start);

    /** if child start is closer than previous closest, set it as closest * */
    if (absDistance < absClosest) {
      absClosest = absDistance;
      closestChild = child;
    }
  }

  return closestChild;
}
 

View findOneVisibleChild(int fromIndex, int toIndex, boolean completelyVisible,
                         boolean acceptPartiallyVisible) {
  OrientationHelper helper;
  if (layoutManager.canScrollVertically()) {
    helper = OrientationHelper.createVerticalHelper(layoutManager);
  } else {
    helper = OrientationHelper.createHorizontalHelper(layoutManager);
  }

  final int start = helper.getStartAfterPadding();
  final int end = helper.getEndAfterPadding();
  final int next = toIndex > fromIndex ? 1 : -1;
  View partiallyVisible = null;
  for (int i = fromIndex; i != toIndex; i += next) {
    final View child = layoutManager.getChildAt(i);
    final int childStart = helper.getDecoratedStart(child);
    final int childEnd = helper.getDecoratedEnd(child);
    if (childStart < end && childEnd > start) {
      if (completelyVisible) {
        if (childStart >= start && childEnd <= end) {
          return child;
        } else if (acceptPartiallyVisible && partiallyVisible == null) {
          partiallyVisible = child;
        }
      } else {
        return child;
      }
    }
  }
  return partiallyVisible;
}
 

private int getDistanceToStart(View targetView, @NonNull OrientationHelper helper) {
    int distance;
    // If we don't care about padding, just snap to the start of the view
    if (!snapToPadding) {
        int childStart = helper.getDecoratedStart(targetView);
        if (childStart >= helper.getStartAfterPadding() / 2) {
            distance = childStart - helper.getStartAfterPadding();
        } else {
            distance = childStart;
        }
    } else {
        distance = helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
    }
    return distance;
}
 

View findOneVisibleChild(int fromIndex, int toIndex, boolean completelyVisible,
    boolean acceptPartiallyVisible) {
  OrientationHelper helper;
  if (layoutManager.canScrollVertically()) {
    helper = OrientationHelper.createVerticalHelper(layoutManager);
  } else {
    helper = OrientationHelper.createHorizontalHelper(layoutManager);
  }

  final int start = helper.getStartAfterPadding();
  final int end = helper.getEndAfterPadding();
  final int next = toIndex > fromIndex ? 1 : -1;
  View partiallyVisible = null;
  for (int i = fromIndex; i != toIndex; i += next) {
    final View child = layoutManager.getChildAt(i);
    final int childStart = helper.getDecoratedStart(child);
    final int childEnd = helper.getDecoratedEnd(child);
    if (childStart < end && childEnd > start) {
      if (completelyVisible) {
        if (childStart >= start && childEnd <= end) {
          return child;
        } else if (acceptPartiallyVisible && partiallyVisible == null) {
          partiallyVisible = child;
        }
      } else {
        return child;
      }
    }
  }
  return partiallyVisible;
}
 

private View findOneVisibleChild(int fromIndex, int toIndex, boolean completelyVisible,
                                 boolean acceptPartiallyVisible) {
    OrientationHelper helper;
    if (layoutManager.canScrollVertically()) {
        helper = OrientationHelper.createVerticalHelper(layoutManager);
    } else {
        helper = OrientationHelper.createHorizontalHelper(layoutManager);
    }

    final int start = helper.getStartAfterPadding();
    final int end = helper.getEndAfterPadding();
    final int next = toIndex > fromIndex ? 1 : -1;
    View partiallyVisible = null;
    for (int i = fromIndex; i != toIndex; i += next) {
        final View child = layoutManager.getChildAt(i);
        final int childStart = helper.getDecoratedStart(child);
        final int childEnd = helper.getDecoratedEnd(child);
        if (childStart < end && childEnd > start) {
            if (completelyVisible) {
                if (childStart >= start && childEnd <= end) {
                    return child;
                } else if (acceptPartiallyVisible && partiallyVisible == null) {
                    partiallyVisible = child;
                }
            } else {
                return child;
            }
        }
    }
    return partiallyVisible;
}
 

View findOneVisibleChild(int fromIndex, int toIndex, boolean completelyVisible,
                         boolean acceptPartiallyVisible) {
    OrientationHelper helper;
    if (linearLayoutManager.canScrollVertically()) {
        helper = OrientationHelper.createVerticalHelper(linearLayoutManager);
    } else {
        helper = OrientationHelper.createHorizontalHelper(linearLayoutManager);
    }

    final int start = helper.getStartAfterPadding();
    final int end = helper.getEndAfterPadding();
    final int next = toIndex > fromIndex ? 1 : -1;
    View partiallyVisible = null;
    for (int i = fromIndex; i != toIndex; i += next) {
        final View child = linearLayoutManager.getChildAt(i);
        final int childStart = helper.getDecoratedStart(child);
        final int childEnd = helper.getDecoratedEnd(child);
        if (childStart < end && childEnd > start) {
            if (completelyVisible) {
                if (childStart >= start && childEnd <= end) {
                    return child;
                } else if (acceptPartiallyVisible && partiallyVisible == null) {
                    partiallyVisible = child;
                }
            } else {
                return child;
            }
        }
    }
    return partiallyVisible;
}
 

private int distanceToStart(View targetView, OrientationHelper helper, boolean fromEnd) {
    if (isRtlHorizontal && !fromEnd) {
        return distanceToEnd(targetView, helper, true);
    }

    return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
}
 

private View findEndView(RecyclerView.LayoutManager layoutManager,
                         OrientationHelper helper) {

    if (layoutManager instanceof LinearLayoutManager) {
        int lastChild = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();

        if (lastChild == RecyclerView.NO_POSITION) {
            return null;
        }

        View child = layoutManager.findViewByPosition(lastChild);

        float visibleWidth;

        if (isRtlHorizontal) {
            visibleWidth = (float) helper.getDecoratedEnd(child)
                    / helper.getDecoratedMeasurement(child);
        } else {
            visibleWidth = (float) (helper.getTotalSpace() - helper.getDecoratedStart(child))
                    / helper.getDecoratedMeasurement(child);
        }

        // If we're at the start of the list, we shouldn't snap
        // to avoid having the first item not completely visible.
        boolean startOfList = ((LinearLayoutManager) layoutManager)
                .findFirstCompletelyVisibleItemPosition() == 0;

        if (visibleWidth > 0.5f && !startOfList) {
            return child;
        } else if (startOfList) {
            return null;
        } else {
            // If the child wasn't returned, we need to return the previous view
            return layoutManager.findViewByPosition(lastChild - 1);
        }
    }
    return null;
}
 

private int distanceStart(View targetView, OrientationHelper helper) {
  int childStart = helper.getDecoratedStart(targetView);
  int containerStart = helper.getStartAfterPadding();
  return childStart - containerStart;
}
 

/**
 * Returns the first view that we should snap to.
 *
 * @param layoutManager the recyclerview's layout manager
 * @param helper        orientation helper to calculate view sizes
 * @return the first view in the LayoutManager to snap to
 */
private View findStartView(RecyclerView.LayoutManager layoutManager,
                           OrientationHelper helper) {

    if (layoutManager instanceof LinearLayoutManager) {
        int firstChild = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
        int offset = 1;

        if (layoutManager instanceof GridLayoutManager) {
            offset += ((GridLayoutManager) layoutManager).getSpanCount() - 1;
        }

        if (firstChild == RecyclerView.NO_POSITION) {
            return null;
        }

        View child = layoutManager.findViewByPosition(firstChild);

        float visibleWidth;

        // We should return the child if it's visible width
        // is greater than 0.5 of it's total width.
        // In a RTL configuration, we need to check the start point and in LTR the end point
        if (isRtlHorizontal) {
            visibleWidth = (float) (helper.getTotalSpace() - helper.getDecoratedStart(child))
                    / helper.getDecoratedMeasurement(child);
        } else {
            visibleWidth = (float) helper.getDecoratedEnd(child)
                    / helper.getDecoratedMeasurement(child);
        }

        // If we're at the end of the list, we shouldn't snap
        // to avoid having the last item not completely visible.
        boolean endOfList = ((LinearLayoutManager) layoutManager)
                .findLastCompletelyVisibleItemPosition()
                == layoutManager.getItemCount() - 1;

        if (visibleWidth > 0.5f && !endOfList) {
            return child;
        } else if (snapLastItem && endOfList) {
            return child;
        } else if (endOfList) {
            return null;
        } else {
            // If the child wasn't returned, we need to return
            // the next view close to the start.
            return layoutManager.findViewByPosition(firstChild + offset);
        }
    }

    return null;
}
 

private View findEndView(RecyclerView.LayoutManager layoutManager,
                         OrientationHelper helper) {

    if (layoutManager instanceof LinearLayoutManager) {
        int lastChild = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
        int offset = 1;

        if (layoutManager instanceof GridLayoutManager) {
            offset += ((GridLayoutManager) layoutManager).getSpanCount() - 1;
        }

        if (lastChild == RecyclerView.NO_POSITION) {
            return null;
        }

        View child = layoutManager.findViewByPosition(lastChild);

        float visibleWidth;

        if (isRtlHorizontal) {
            visibleWidth = (float) helper.getDecoratedEnd(child)
                    / helper.getDecoratedMeasurement(child);
        } else {
            visibleWidth = (float) (helper.getTotalSpace() - helper.getDecoratedStart(child))
                    / helper.getDecoratedMeasurement(child);
        }

        // If we're at the start of the list, we shouldn't snap
        // to avoid having the first item not completely visible.
        boolean startOfList = ((LinearLayoutManager) layoutManager)
                .findFirstCompletelyVisibleItemPosition() == 0;

        if (visibleWidth > 0.5f && !startOfList) {
            return child;
        } else if (snapLastItem && startOfList) {
            return child;
        } else if (startOfList) {
            return null;
        } else {
            // If the child wasn't returned, we need to return the previous view
            return layoutManager.findViewByPosition(lastChild - offset);
        }
    }
    return null;
}
 

private int distanceToStart(View targetView, OrientationHelper helper) {
  return helper.getDecoratedStart(targetView) - helper.getStartAfterPadding();
}
 

/**
 * Returns the first view that we should snap to.
 *
 * @param layoutManager the recyclerview's layout manager
 * @param helper        orientation helper to calculate view sizes
 * @return the first view in the LayoutManager to snap to
 */
private View findStartView(RecyclerView.LayoutManager layoutManager,
                           OrientationHelper helper) {

    if (layoutManager instanceof LinearLayoutManager) {
        int firstChild = ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();

        if (firstChild == RecyclerView.NO_POSITION) {
            return null;
        }

        View child = layoutManager.findViewByPosition(firstChild);

        float visibleWidth;

        // We should return the child if it's visible width
        // is greater than 0.5 of it's total width.
        // In a RTL configuration, we need to check the start point and in LTR the end point
        if (isRtlHorizontal) {
            visibleWidth = (float) (helper.getTotalSpace() - helper.getDecoratedStart(child))
                    / helper.getDecoratedMeasurement(child);
        } else {
            visibleWidth = (float) helper.getDecoratedEnd(child)
                    / helper.getDecoratedMeasurement(child);
        }

        // If we're at the end of the list, we shouldn't snap
        // to avoid having the last item not completely visible.
        boolean endOfList = ((LinearLayoutManager) layoutManager)
                .findLastCompletelyVisibleItemPosition()
                == layoutManager.getItemCount() - 1;

        if (visibleWidth > 0.5f && !endOfList) {
            return child;
        } else if (endOfList) {
            return null;
        } else {
            // If the child wasn't returned, we need to return
            // the next view close to the start.
            return layoutManager.findViewByPosition(firstChild + 1);
        }
    }

    return null;
}