GridSpacingItemDecoration.java

/*
 * Copyright (c) 2016 Karina 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.mirhoseini.marvel.util;

import android.graphics.Rect;
import android.support.v4.text.TextUtilsCompat;
import android.support.v4.view.ViewCompat;
import android.support.v7.widget.RecyclerView;
import android.view.View;

import java.util.Locale;

/**
 * Created by Mohsen on 20/10/2016.
 */

public class GridSpacingItemDecoration extends RecyclerView.ItemDecoration {

    private int spanCount;
    private int spacing;
    private boolean includeEdge;
    private int headerNum;
    private boolean isRtl = TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault()) == ViewCompat.LAYOUT_DIRECTION_RTL;

    public GridSpacingItemDecoration(int spanCount, int spacing, boolean includeEdge, int headerNum) {
        this.spanCount = spanCount;
        this.spacing = spacing;
        this.includeEdge = includeEdge;
        this.headerNum = headerNum;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        int position = parent.getChildAdapterPosition(view) - headerNum; // item position
        if (position >= 0) {
            int column = position % spanCount; // item column
            if (isRtl) {
                column = spanCount - 1 - column;
            }
            if (includeEdge) {
                outRect.left = spacing - column * spacing / spanCount;
                outRect.right = (column + 1) * spacing / spanCount;

                if (position < spanCount) { // top edge
                    outRect.top = spacing;
                }
                outRect.bottom = spacing; // item bottom
            } else {
                outRect.left = column * spacing / spanCount;
                outRect.right = spacing - (column + 1) * spacing / spanCount;
                if (position >= spanCount) {
                    outRect.top = spacing; // item top
                }
            }
        } else {
            outRect.left = spacing;
            outRect.right = spacing;
            if (includeEdge)
                outRect.top = spacing;
            else
                outRect.top = 0;
            outRect.bottom = 0;
        }
    }

}