| /* |
| * Copyright 2018 The Android Open Source Project |
| * |
| * 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 androidx.recyclerview.widget; |
| |
| import android.view.View; |
| |
| /** |
| * Helper class that keeps temporary state while {LayoutManager} is filling out the empty |
| * space. |
| */ |
| class LayoutState { |
| |
| static final int LAYOUT_START = -1; |
| |
| static final int LAYOUT_END = 1; |
| |
| static final int INVALID_LAYOUT = Integer.MIN_VALUE; |
| |
| static final int ITEM_DIRECTION_HEAD = -1; |
| |
| static final int ITEM_DIRECTION_TAIL = 1; |
| |
| /** |
| * We may not want to recycle children in some cases (e.g. layout) |
| */ |
| boolean mRecycle = true; |
| |
| /** |
| * Number of pixels that we should fill, in the layout direction. |
| */ |
| int mAvailable; |
| |
| /** |
| * Current position on the adapter to get the next item. |
| */ |
| int mCurrentPosition; |
| |
| /** |
| * Defines the direction in which the data adapter is traversed. |
| * Should be {@link #ITEM_DIRECTION_HEAD} or {@link #ITEM_DIRECTION_TAIL} |
| */ |
| int mItemDirection; |
| |
| /** |
| * Defines the direction in which the layout is filled. |
| * Should be {@link #LAYOUT_START} or {@link #LAYOUT_END} |
| */ |
| int mLayoutDirection; |
| |
| /** |
| * This is the target pixel closest to the start of the layout that we are trying to fill |
| */ |
| int mStartLine = 0; |
| |
| /** |
| * This is the target pixel closest to the end of the layout that we are trying to fill |
| */ |
| int mEndLine = 0; |
| |
| /** |
| * If true, layout should stop if a focusable view is added |
| */ |
| boolean mStopInFocusable; |
| |
| /** |
| * If the content is not wrapped with any value |
| */ |
| boolean mInfinite; |
| |
| /** |
| * @return true if there are more items in the data adapter |
| */ |
| boolean hasMore(RecyclerView.State state) { |
| return mCurrentPosition >= 0 && mCurrentPosition < state.getItemCount(); |
| } |
| |
| /** |
| * Gets the view for the next element that we should render. |
| * Also updates current item index to the next item, based on {@link #mItemDirection} |
| * |
| * @return The next element that we should render. |
| */ |
| View next(RecyclerView.Recycler recycler) { |
| final View view = recycler.getViewForPosition(mCurrentPosition); |
| mCurrentPosition += mItemDirection; |
| return view; |
| } |
| |
| @Override |
| public String toString() { |
| return "LayoutState{" |
| + "mAvailable=" + mAvailable |
| + ", mCurrentPosition=" + mCurrentPosition |
| + ", mItemDirection=" + mItemDirection |
| + ", mLayoutDirection=" + mLayoutDirection |
| + ", mStartLine=" + mStartLine |
| + ", mEndLine=" + mEndLine |
| + '}'; |
| } |
| } |