package com.marshalchen.ultimaterecyclerview; 
 
import android.content.Context; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.view.View; 
import android.view.ViewGroup; 
 
/** 
 * Created by cym on 15/5/27. 
 */ 
public class CustomLinearLayoutManager extends LinearLayoutManager { 
 
    public CustomLinearLayoutManager(Context context, int orientation, boolean reverseLayout)    { 
        super(context, orientation, reverseLayout); 
    } 
 
    private int[] mMeasuredDimension = new int[2]; 
 
    @Override 
    public void onMeasure(RecyclerView.Recycler recycler, RecyclerView.State state, 
                          int widthSpec, int heightSpec) { 
        final int widthMode = View.MeasureSpec.getMode(widthSpec); 
        final int heightMode = View.MeasureSpec.getMode(heightSpec); 
        final int widthSize = View.MeasureSpec.getSize(widthSpec); 
        final int heightSize = View.MeasureSpec.getSize(heightSpec); 
        int width = 0; 
        int height = 0; 
        for (int i = 0; i < getItemCount(); i++) { 
            measureScrapChild(recycler, i, 
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), 
                    View.MeasureSpec.makeMeasureSpec(i, View.MeasureSpec.UNSPECIFIED), 
                    mMeasuredDimension); 
 
            if (getOrientation() == HORIZONTAL) { 
                width = width + mMeasuredDimension[0]; 
                if (i == 0) { 
                    height = mMeasuredDimension[1]; 
                } 
            } else { 
                height = height + mMeasuredDimension[1]; 
                if (i == 0) { 
                    width = mMeasuredDimension[0]; 
                } 
            } 
        } 
        switch (widthMode) { 
            case View.MeasureSpec.EXACTLY: 
                width = widthSize; 
            case View.MeasureSpec.AT_MOST: 
            case View.MeasureSpec.UNSPECIFIED: 
        } 
 
        switch (heightMode) { 
            case View.MeasureSpec.EXACTLY: 
                height = heightSize; 
            case View.MeasureSpec.AT_MOST: 
            case View.MeasureSpec.UNSPECIFIED: 
        } 
 
        setMeasuredDimension(width, height); 
    } 
 
    private void measureScrapChild(RecyclerView.Recycler recycler, int position, int widthSpec, 
                                   int heightSpec, int[] measuredDimension) { 
        View view = recycler.getViewForPosition(position); 
        if (view != null) { 
            RecyclerView.LayoutParams p = (RecyclerView.LayoutParams) view.getLayoutParams(); 
            int childWidthSpec = ViewGroup.getChildMeasureSpec(widthSpec, 
                    getPaddingLeft() + getPaddingRight(), p.width); 
            int childHeightSpec = ViewGroup.getChildMeasureSpec(heightSpec, 
                    getPaddingTop() + getPaddingBottom(), p.height); 
            view.measure(childWidthSpec, childHeightSpec); 
            measuredDimension[0] = view.getMeasuredWidth() + p.leftMargin + p.rightMargin; 
            measuredDimension[1] = view.getMeasuredHeight() + p.bottomMargin + p.topMargin; 
            recycler.recycleView(view); 
        } 
    } 
}