RecyclerView在GridLayoutManager情况下实现四周都有分割线的ItemDecoration

来源：互联网发布：mac锁定触控板快捷键编辑：程序博客网时间：2024/06/05 20:01

感谢:http://www.jianshu.com/p/d58cbd61c40a _SOLID

之前UI有个比较特别的需求,一个gridview形式的列表,但是四周都有白色的分割线:
这里写图片描述

类似这个效果,一开始以为会比较简单,然后写了之后才发现,目前网上找到的大部分方法话分割线都是省略掉屏幕边缘的部分的,
即第一行第一列最后一行最后一列的没有分割线的

http://blog.csdn.net/lmj623565791/article/details/45059587
如hongyang大神的这个文章中就是这种典型的gridview的ItemDecoration

于是在掘金和github找了很久,终于找到一个符合一般要求的—最后一行也与分割线,虽然第一行还是没有,不过既然最后一行都有了,第一韩有也不难了

http://www.jianshu.com/p/d58cbd61c40a
自定义ItemDecoration这个问题你真的注意到了吗—–_SOLID

这个博客贴出的ItemDecoration正好拿来改造一番

关键代码在于:

 private boolean isfirstRow(RecyclerView parent, int pos, int spanCount,                               int childCount) {        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            // childCount = childCount - childCount % spanCount;            int lines = childCount % spanCount == 0 ? childCount / spanCount : childCount / spanCount + 1;             //如是第一行则返回true            if ((pos / spanCount + 1) == 1) {                return true;            } else {                return false;            }        } else if (layoutManager instanceof StaggeredGridLayoutManager) {            int orientation = ((StaggeredGridLayoutManager) layoutManager)                    .getOrientation();            // StaggeredGridLayoutManager 且纵向滚动            if (orientation == StaggeredGridLayoutManager.VERTICAL) {                childCount = childCount - childCount % spanCount;                // 如果是最后一行，则不需要绘制底部                if (pos >= childCount)                    return true;            } else {                // 如果是最后一行，则不需要绘制底部                if ((pos + 1) % spanCount == 0) {                    return true;                }            }        }        return false;    }

在这个方法里判断当前是否是第一行 (pos / spanCount + 1) == 1 这个就是关键代码
然后在getItemOffsets()方法中做一个判断

 if (isfirstRow) {            top = (spanCount - 1) * mDividerWidth / spanCount;        } else {            top = 0;        }outRect.set(left, top, right, bottom);

计算item的偏差值,如果是第一行则set上去.

一下为全部代码:

package Tools;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.Rect;import android.support.annotation.ColorInt;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.StaggeredGridLayoutManager;import android.view.View;/** * Gridview * 四周都是分割线的ItemDecoration,因为网上都是RecyclerView的边框部分没有分割线,主要代码在于用isfirstRow去判断 * Created by _SOLID * Date:2016/10/8 * Time:16:50 * Desc: */public class GridDividerItemDecoration extends RecyclerView.ItemDecoration {    private Paint mPaint;    private int mDividerWidth;    public GridDividerItemDecoration(int height, @ColorInt int color) {        mDividerWidth = height;        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);        mPaint.setColor(color);        mPaint.setStyle(Paint.Style.FILL);    }    @Override    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {        super.getItemOffsets(outRect, view, parent, state);        int itemPosition = ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewLayoutPosition();        int spanCount = getSpanCount(parent);        int childCount = parent.getAdapter().getItemCount();        boolean isLastRow = isLastRow(parent, itemPosition, spanCount, childCount);        boolean isfirstRow = isfirstRow(parent, itemPosition, spanCount, childCount);        int top;        int left;        int right;        int bottom;        int eachWidth = (spanCount - 1) * mDividerWidth / spanCount;        int dl = mDividerWidth - eachWidth;        left = itemPosition % spanCount * dl;        right = eachWidth - left;        bottom = mDividerWidth;        //Log.e("zzz", "itemPosition:" + itemPosition + " |left:" + left + " right:" + right + " bottom:" + bottom);//        if (isLastRow) {//            bottom = 0;//        }        if (isfirstRow) {            top = (spanCount - 1) * mDividerWidth / spanCount;        } else {            top = 0;        }        outRect.set(left, top, right, bottom);    }    @Override    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {        super.onDraw(c, parent, state);        draw(c, parent);    }    //绘制横向 item 分割线    private void draw(Canvas canvas, RecyclerView parent) {        int childSize = parent.getChildCount();        for (int i = 0; i < childSize; i++) {            View child = parent.getChildAt(i);            RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();            //画水平分隔线            int left = child.getLeft();            int right = child.getRight();            int top = child.getBottom() + layoutParams.bottomMargin;            int bottom = top + mDividerWidth;            if (mPaint != null) {                canvas.drawRect(left, top, right, bottom, mPaint);            }            //画垂直分割线            top = child.getTop();            bottom = child.getBottom() + mDividerWidth;            left = child.getRight() + layoutParams.rightMargin;            right = left + mDividerWidth;            if (mPaint != null) {                canvas.drawRect(left, top, right, bottom, mPaint);            }        }    }    private boolean isLastColumn(RecyclerView parent, int pos, int spanCount,                                 int childCount) {        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            if ((pos + 1) % spanCount == 0) {// 如果是最后一列，则不需要绘制右边                return true;            }        } else if (layoutManager instanceof StaggeredGridLayoutManager) {            int orientation = ((StaggeredGridLayoutManager) layoutManager)                    .getOrientation();            if (orientation == StaggeredGridLayoutManager.VERTICAL) {                if ((pos + 1) % spanCount == 0)// 如果是最后一列，则不需要绘制右边                {                    return true;                }            } else {                childCount = childCount - childCount % spanCount;                if (pos >= childCount)// 如果是最后一列，则不需要绘制右边                    return true;            }        }        return false;    }    private boolean isLastRow(RecyclerView parent, int pos, int spanCount,                              int childCount) {        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            // childCount = childCount - childCount % spanCount;            int lines = childCount % spanCount == 0 ? childCount / spanCount : childCount / spanCount + 1;            return lines == pos / spanCount + 1;        } else if (layoutManager instanceof StaggeredGridLayoutManager) {            int orientation = ((StaggeredGridLayoutManager) layoutManager)                    .getOrientation();            // StaggeredGridLayoutManager 且纵向滚动            if (orientation == StaggeredGridLayoutManager.VERTICAL) {                childCount = childCount - childCount % spanCount;                // 如果是最后一行，则不需要绘制底部                if (pos >= childCount)                    return true;            } else {                // 如果是最后一行，则不需要绘制底部                if ((pos + 1) % spanCount == 0) {                    return true;                }            }        }        return false;    }    private boolean isfirstRow(RecyclerView parent, int pos, int spanCount,                               int childCount) {        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            // childCount = childCount - childCount % spanCount;            int lines = childCount % spanCount == 0 ? childCount / spanCount : childCount / spanCount + 1;            //如是第一行则返回true            if ((pos / spanCount + 1) == 1) {                return true;            } else {                return false;            }        } else if (layoutManager instanceof StaggeredGridLayoutManager) {            int orientation = ((StaggeredGridLayoutManager) layoutManager)                    .getOrientation();            // StaggeredGridLayoutManager 且纵向滚动            if (orientation == StaggeredGridLayoutManager.VERTICAL) {                childCount = childCount - childCount % spanCount;                // 如果是最后一行，则不需要绘制底部                if (pos >= childCount)                    return true;            } else {                // 如果是最后一行，则不需要绘制底部                if ((pos + 1) % spanCount == 0) {                    return true;                }            }        }        return false;    }    private int getSpanCount(RecyclerView parent) {        // 列数        int spanCount = -1;        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            spanCount = ((GridLayoutManager) layoutManager).getSpanCount();        } else if (layoutManager instanceof StaggeredGridLayoutManager) {            spanCount = ((StaggeredGridLayoutManager) layoutManager)                    .getSpanCount();        }        return spanCount;    }}

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