import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import 
 
com.tiangui.R;
/**
 * 檔案描述：
 * 作者：Created by BiJingCun on 2018/6/1.
 */
public class CustomDecoration extends RecyclerView.ItemDecoration {

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;
    private 
 
Drawable mDivider;
    private int mOrientation;
/**
     * 分割線縮排值
     */
private int inset;
    private Paint paint;
/**
     * @param context * @param orientation layout的方向  * @param drawable  引入的drawable的ID  * @param inset    分割線縮排值
     */
public CustomDecoration(Context context, int orientation, int 
 
drawable, int inset) {
        mDivider = context.getResources().getDrawable(drawable);
        this.inset = inset;
paint = new Paint();
paint.setColor(context.getResources().getColor(R.color.color_white));
paint.setStyle(Paint.Style.FILL);
paint.setAntiAlias(true);
setOrientation(orientation);
}

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
}
        mOrientation = orientation;
}

    @Override
public void onDraw(Canvas c, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
} else {
            drawHorizontal(c, parent);
}
    }

    private void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();
        final int childCount = parent.getChildCount();
//最後一個item不畫分割線
for (int i = 0; i < childCount - 1; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            if (inset > 0) {
                c.drawRect(left, top, right, bottom, paint);
mDivider.setBounds(left + inset, top, right - inset, bottom);
} else {
                mDivider.setBounds(left, top, right, bottom);
}
            mDivider.draw(c);
}
    }

    private void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount - 1; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
    }

    //由於Divider也有寬高，每一個Item需要向下或者向右偏移
@Override
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
}
    }
}