RecyclerView網格分割線

網格的分割線實現起來和線性差不了多少，主要注意的是，當達到最后一行時，不繪制橫線，當達到最后一列時，不繪制豎線，

public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { super.getItemOffsets(outRect, view, parent, state); int spanCount = getSpanCount(parent); int childCount = parent.getAdapter().getItemCount(); if (isLastRaw(parent, spanCount, childCount))// 如果是最后一行，則不需要繪制底部
 { outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } else if (isLastColum(parent, spanCount, view))// 如果是最后一列，則不需要繪制右邊
 { outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else { outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight()); } }

接下來解釋最后一行和最后一列的2個方法。

我們設置GridLayoutManager的時候，參數里設置了這個網格的spanCount。

當recyclerview的子view總數%spanCount的值為0，或者值小於spanCount時，即表示當前繪制的網格處於recyclerview的最后一行。

private boolean isLastRaw(RecyclerView parent, int spanCount, int childCount) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { if (childCount % spanCount == 0 || childCount % spanCount < spanCount) return true; } return false; }

這個方法中值得注意的是view，主要用來獲取當前的位置。由於位置坐標從0算起，所以，當pos+1的值%spanCount為0時，即可表示當前是處於最后一列上。

private boolean isLastColum(RecyclerView parent, int spanCount, View view) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); int pos = layoutManager.getPosition(view); if (layoutManager instanceof GridLayoutManager) { if ((pos + 1) % spanCount == 0) {// 如果是最后一列，則不需要繪制右邊
                return true; } } return false; }

之后，參照繪制線性分割線時繪制橫豎2條線即可。

MyItemDecoration整體代碼：

class MyItemDecoration extends RecyclerView.ItemDecoration { private static final int[] ATTRS = new int[]{android.R.attr.listDivider}; private Drawable mDivider; public MyItemDecoration(Context context) { final TypedArray a = context.obtainStyledAttributes(ATTRS); mDivider = a.getDrawable(0); a.recycle(); } @Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) { drawHorizontal(c, parent); drawVertical(c, parent); } private int getSpanCount(RecyclerView parent) { // 列數
        int spanCount = -1; RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { spanCount = ((GridLayoutManager) layoutManager).getSpanCount(); } return spanCount; } public void drawHorizontal(Canvas c, RecyclerView parent) { int childCount = parent.getChildCount(); 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 = child.getRight() + params.rightMargin + mDivider.getIntrinsicWidth(); final int top = child.getBottom() + params.bottomMargin; final int bottom = top + mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } public void drawVertical(Canvas c, RecyclerView parent) { final int childCount = parent.getChildCount(); 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 + mDivider.getIntrinsicWidth(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(c); } } private boolean isLastColum(RecyclerView parent, int spanCount, View view) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); int pos = layoutManager.getPosition(view); if (layoutManager instanceof GridLayoutManager) { if ((pos + 1) % spanCount == 0) {// 如果是最后一列，則不需要繪制右邊
                return true; } } return false; } private boolean isLastRaw(RecyclerView parent, int spanCount, int childCount) { RecyclerView.LayoutManager layoutManager = parent.getLayoutManager(); if (layoutManager instanceof GridLayoutManager) { if (childCount % spanCount == 0 || childCount % spanCount < spanCount) return true; } return false; } @Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) { super.getItemOffsets(outRect, view, parent, state); int spanCount = getSpanCount(parent); int childCount = parent.getAdapter().getItemCount(); if (isLastRaw(parent, spanCount, childCount))// 如果是最后一行，則不需要繪制底部
 { outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } else if (isLastColum(parent, spanCount, view))// 如果是最后一列，則不需要繪制右邊
 { outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else { outRect.set(0, 0, mDivider.getIntrinsicWidth(), mDivider.getIntrinsicHeight()); } } }