127 lines
4.0 KiB
Java
127 lines
4.0 KiB
Java
/*
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* Copyright 2016 Hippo Seven
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.hippo.widget.recyclerview;
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import android.content.Context;
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import android.support.v7.widget.GridLayoutManager;
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import android.support.v7.widget.RecyclerView;
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import java.util.ArrayList;
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import java.util.List;
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public class AutoGridLayoutManager extends GridLayoutManager {
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public static final int STRATEGY_MIN_SIZE = 0;
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public static final int STRATEGY_SUITABLE_SIZE = 1;
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private int mColumnSize = -1;
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private boolean mColumnSizeChanged = true;
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private int mStrategy;
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private List<OnUpdateSpanCountListener> mListeners;
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public AutoGridLayoutManager(Context context, int columnSize) {
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super(context, 1);
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setColumnSize(columnSize);
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}
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public AutoGridLayoutManager(Context context, int columnSize, int orientation, boolean reverseLayout) {
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super(context, 1, orientation, reverseLayout);
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setColumnSize(columnSize);
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}
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public void setColumnSize(int columnSize) {
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if (columnSize == mColumnSize) {
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return;
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}
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mColumnSize = columnSize;
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mColumnSizeChanged = true;
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}
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public void setStrategy(int strategy) {
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if (strategy == mStrategy) {
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return;
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}
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mStrategy = strategy;
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mColumnSizeChanged = true;
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}
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public static int getSpanCountForSuitableSize(int total, int single) {
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int span = total / single;
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if (span <= 0) {
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return 1;
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}
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int span2 = span + 1;
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float deviation = Math.abs(1 - (total / span / (float) single));
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float deviation2 = Math.abs(1 - (total / span2 / (float) single));
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return deviation < deviation2 ? span : span2;
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}
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public static int getSpanCountForMinSize(int total, int single) {
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return Math.max(1, total / single);
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}
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@Override
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public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
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if (mColumnSizeChanged && mColumnSize > 0) {
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int totalSpace;
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if (getOrientation() == VERTICAL) {
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totalSpace = getWidth() - getPaddingRight() - getPaddingLeft();
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} else {
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totalSpace = getHeight() - getPaddingTop() - getPaddingBottom();
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}
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int spanCount;
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switch (mStrategy) {
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default:
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case STRATEGY_MIN_SIZE:
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spanCount = getSpanCountForMinSize(totalSpace, mColumnSize);
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break;
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case STRATEGY_SUITABLE_SIZE:
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spanCount = getSpanCountForSuitableSize(totalSpace, mColumnSize);
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break;
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}
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setSpanCount(spanCount);
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mColumnSizeChanged = false;
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if (null != mListeners) {
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for (int i = 0, n = mListeners.size(); i < n; i++) {
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mListeners.get(i).onUpdateSpanCount(spanCount);
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}
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}
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}
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super.onLayoutChildren(recycler, state);
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}
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public void addOnUpdateSpanCountListener(OnUpdateSpanCountListener listener) {
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if (null == mListeners) {
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mListeners = new ArrayList<>();
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}
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mListeners.add(listener);
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}
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public void removeOnUpdateSpanCountListener(OnUpdateSpanCountListener listener) {
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if (null != mListeners) {
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mListeners.remove(listener);
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}
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}
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public interface OnUpdateSpanCountListener {
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void onUpdateSpanCount(int spanCount);
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}
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}
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