com.uphyca.recyclerviewcommons.DividerItemDecoration.java Source code

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Here is the source code for com.uphyca.recyclerviewcommons.DividerItemDecoration.java

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/*
 * Copyright (C) 2016 uPhyca Inc.
 *
 * 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.uphyca.recyclerviewcommons;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * Draw divider for vertical non-reverse LinearLayoutManager.
 * Divider will drawn only between same viewType item.
 */
public class DividerItemDecoration extends RecyclerView.ItemDecoration {

    private final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final int dividerHeight;
    private final int dividerMargin;

    public DividerItemDecoration(int color, int height) {
        this(color, height, 0);
    }

    public DividerItemDecoration(int color, int height, int margin) {
        this.dividerHeight = height;
        this.dividerMargin = margin;
        paint.setColor(color);
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        super.onDraw(c, parent, state);

        final RecyclerView.LayoutManager manager = parent.getLayoutManager();

        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();
        if (childCount < 2) {
            return;
        }

        int lastItemViewType = -1;
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.ViewHolder childViewHolder = parent.getChildViewHolder(child);
            final int itemViewType = childViewHolder.getItemViewType();
            if (itemViewType == lastItemViewType) {
                RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
                // ViewCompat.getTranslationY() needs for add/delete animation
                final int top = manager.getDecoratedTop(child) - params.topMargin
                        + Math.round(ViewCompat.getTranslationY(child));
                final int bottom = top + dividerHeight;
                c.drawRect(left + dividerMargin, top, right - dividerMargin, bottom, paint);
            }
            lastItemViewType = itemViewType;
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        super.getItemOffsets(outRect, view, parent, state);
        final RecyclerView.ViewHolder childViewHolder = parent.getChildViewHolder(view);
        final int position = childViewHolder.getLayoutPosition();
        if (position > 0) {
            final int itemViewType = childViewHolder.getItemViewType();
            if (itemViewType == parent.getAdapter().getItemViewType(position - 1)) {
                // offset for divider
                if (outRect.top < dividerHeight) {
                    outRect.top = dividerHeight;
                }
            }
        }
    }
}