一款灵活的RecyclerView的网格布局分割线

      前文有讲RecyclerView的分割线问题，并给出了一款实用的线性布局分割线：http://blog.csdn.net/qq_34995257/article/details/70212797

      但我知道广大基友肯定不会满足的，毕竟没有讲使用GridLayoutManager时的情况。所以兄弟我决定再使把力，参照各路资料，把这一种情况的divider封装类也整理出来，只求大家能够喜欢。

import android.graphics.Canvas;import android.graphics.Rect;import android.graphics.drawable.ColorDrawable;import android.graphics.drawable.Drawable;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.RecyclerView;import android.view.View;public class GridDivider extends RecyclerView.ItemDecoration {    private int spacing;    private boolean isIncludeEdge;    private int vertivalSpacing;    private Drawable mDivider;    public GridDivider(int spacing) {        this.spacing = spacing;        this.isIncludeEdge = false;        this.vertivalSpacing = spacing;    }    public GridDivider(int spacing, int color) {        this.spacing = spacing;        this.isIncludeEdge = false;        this.vertivalSpacing = spacing;        this.mDivider = new ColorDrawable(color);    }    public GridDivider(int spacing, boolean isIncludeEdge) {        this.spacing = spacing;        this.isIncludeEdge = isIncludeEdge;        this.vertivalSpacing = spacing;    }    public GridDivider(int spacing, int vertivalSpacing, boolean isIncludeEdge) {        this.spacing = spacing;        this.isIncludeEdge = isIncludeEdge;        this.vertivalSpacing = vertivalSpacing;    }    public GridDivider(int spacing, int vertivalSpacing, int color, boolean isIncludeEdge) {        this.spacing = spacing;        this.isIncludeEdge = isIncludeEdge;        this.vertivalSpacing = vertivalSpacing;        this.mDivider = new ColorDrawable(color);    }    public void setDivider(Drawable divider) {        this.mDivider = divider;    }    public void setColorDivider(int color) {        this.mDivider = new ColorDrawable(color);    }    public void setSpacing(int spacing) {        this.spacing = spacing;    }    public void setVertivalSpacing(int vertivalSpacing) {        this.vertivalSpacing = vertivalSpacing;    }    public void setIncludeEdge(boolean isIncludeEdge) {        this.isIncludeEdge = isIncludeEdge;    }    @Override    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {        if (mDivider != null) {            drawHorizontal(c, parent);            drawVertical(c, parent);        }    }    private int getSpanCount(RecyclerView parent) {        int spanCount = -1;        RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();        if (layoutManager instanceof GridLayoutManager) {            spanCount = ((GridLayoutManager) layoutManager).getSpanCount();        }        return spanCount;    }    private void drawHorizontal(Canvas c, RecyclerView parent) {        final int childCount = parent.getChildCount();        final int spanCount = getSpanCount(parent);        for (int i = 0; i < childCount; i++) {            final View child = parent.getChildAt(i);            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();            final int left = child.getLeft() - params.leftMargin;            final int right;            if (!isIncludeEdge && i != 0 && (i + 1) % spanCount == 0) {                right = child.getRight() + params.rightMargin;            } else {                right = child.getRight() + params.rightMargin + spacing;            }            final int top = child.getBottom() + params.bottomMargin;            final int bottom = top + vertivalSpacing;            final int lastRaw = childCount % spanCount == 0 ? childCount - spanCount : childCount - childCount % spanCount;            if (isIncludeEdge || i < lastRaw) {                mDivider.setBounds(left, top, right, bottom);                mDivider.draw(c);            }            if (isIncludeEdge && i < spanCount) {                final int edgeTop = child.getTop() - params.topMargin - vertivalSpacing;                final int edgeBottom = child.getTop() - params.topMargin;                final int edgeLeft = i == 0 ? left - spacing : left;                mDivider.setBounds(edgeLeft, edgeTop, right, edgeBottom);                mDivider.draw(c);            }        }    }    private void drawVertical(Canvas c, RecyclerView parent) {        final int childCount = parent.getChildCount();        final int spanCount = getSpanCount(parent);        for (int i = 0; i < childCount; i++) {            final View child = parent.getChildAt(i);            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();            final int top = child.getTop() - params.topMargin;            final int bottom = child.getBottom() + params.bottomMargin;            final int left = child.getRight() + params.rightMargin;            final int right = left + spacing;            if (isIncludeEdge || i == 0 || (i + 1) % spanCount != 0) {                mDivider.setBounds(left, top, right, bottom);                mDivider.draw(c);            }            if (isIncludeEdge && i % spanCount == 0) {                final int edgeBottom = child.getBottom() + params.bottomMargin + vertivalSpacing;                final int edgeLeft = child.getLeft() - params.leftMargin - spacing;                final int edgeRight = child.getLeft() - params.leftMargin;                mDivider.setBounds(edgeLeft, top, edgeRight, edgeBottom);                mDivider.draw(c);            }        }    }    @Override    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {        int position = parent.getChildAdapterPosition(view); // item position        int spanCount = getSpanCount(parent);        int column = position % spanCount; // item column        if (isIncludeEdge) {            outRect.left = spacing - column * spacing / spanCount; // spacing - column * ((1f / spanCount) * spacing)            outRect.right = (column + 1) * spacing / spanCount; // (column + 1) * ((1f / spanCount) * spacing)            if (position < spanCount) { // top edge                outRect.top = spacing;            }            outRect.bottom = vertivalSpacing; // item bottom        } else {            outRect.left = column * spacing / spanCount; // column * ((1f / spanCount) * spacing)            outRect.right = spacing - (column + 1) * spacing / spanCount; // spacing - (column + 1) * ((1f / spanCount) * spacing)            if (position >= spanCount) {                outRect.top = vertivalSpacing; // item top            }        }    }}

      这次的divider可是很灵活的，同样是通过几种不同的构造方法来创建，然后通过addItemDecoration的方式使用。为了应付产品经理各种各样的需求，这次可以通过传入不同的spacing和vertivalSpacing来定制网格布局中横向和纵向宽度不同的分割线。当然，还有喜闻乐见的是否包含边界isIncludeEdge，都没问题。如果没有传入color或者drawable，那么就是透明分割线，最简单的就在构造方法中只传一个spacing，即可创建横纵向宽度为spacing的透明分割线了，非常灵活。

      至于其他需求的分割线，可以参照http://blog.csdn.net/lmj623565791/article/details/45059587这篇文章，定制的关键就在于getItemOffsets和ondraw方法，兄弟只能帮到这里了，剩下的靠你们自己了。