diff --git a/app/src/main/java/com/chad/baserecyclerviewadapterhelper/SectionUseActivity.java b/app/src/main/java/com/chad/baserecyclerviewadapterhelper/SectionUseActivity.java
index ae2987524..15b9f6372 100644
--- a/app/src/main/java/com/chad/baserecyclerviewadapterhelper/SectionUseActivity.java
+++ b/app/src/main/java/com/chad/baserecyclerviewadapterhelper/SectionUseActivity.java
@@ -9,6 +9,7 @@
import com.chad.baserecyclerviewadapterhelper.adapter.SectionAdapter;
import com.chad.baserecyclerviewadapterhelper.base.BaseActivity;
import com.chad.baserecyclerviewadapterhelper.data.DataServer;
+import com.chad.baserecyclerviewadapterhelper.decoration.GridSectionAverageGapItemDecoration;
import com.chad.baserecyclerviewadapterhelper.entity.MySection;
import com.chad.library.adapter.base.BaseQuickAdapter;
@@ -29,6 +30,7 @@ protected void onCreate(Bundle savedInstanceState) {
setTitle("Section Use");
mRecyclerView = (RecyclerView) findViewById(R.id.rv_list);
mRecyclerView.setLayoutManager(new GridLayoutManager(this,2));
+ mRecyclerView.addItemDecoration(new GridSectionAverageGapItemDecoration(50,20,20,20));
mData = DataServer.getSampleData();
SectionAdapter sectionAdapter = new SectionAdapter(R.layout.item_section_content, R.layout.def_section_head, mData);
diff --git a/app/src/main/java/com/chad/baserecyclerviewadapterhelper/decoration/GridSectionAverageGapItemDecoration.java b/app/src/main/java/com/chad/baserecyclerviewadapterhelper/decoration/GridSectionAverageGapItemDecoration.java
new file mode 100644
index 000000000..92de88809
--- /dev/null
+++ b/app/src/main/java/com/chad/baserecyclerviewadapterhelper/decoration/GridSectionAverageGapItemDecoration.java
@@ -0,0 +1,146 @@
+package com.chad.baserecyclerviewadapterhelper.decoration;
+
+import android.graphics.Rect;
+import android.support.v7.widget.GridLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.util.DisplayMetrics;
+import android.util.TypedValue;
+import android.view.View;
+
+import com.chad.library.adapter.base.BaseQuickAdapter;
+import com.chad.library.adapter.base.BaseSectionQuickAdapter;
+import com.chad.library.adapter.base.BaseViewHolder;
+import com.chad.library.adapter.base.entity.SectionEntity;
+
+/**
+ * 应用于RecyclerView的GridLayoutManager，水平方向上固定间距大小，从而使条目宽度自适应。
+ * 配合Brvah的Section使用，不对Head生效，仅对每个Head的子Grid列表生效
+ *Section Grid中Item的宽度应设为MATCH_PARAENT
+ *
+ * @author : renpeng
+ * @org :Aurora Team
+ * @since : 2018/9/29
+ */
+public class GridSectionAverageGapItemDecoration extends RecyclerView.ItemDecoration {
+
+ private float gapHorizontalDp;
+ private float gapVerticalDp;
+ private float sectionEdgeHPaddingDp;
+ private float sectionEdgeVPaddingDp;
+ private int gapHSizePx = -1;
+ private int gapVSizePx = -1;
+ private int sectionEdgeHPaddingPx;
+ private int eachItemHPaddingPx; //每个条目应该在水平方向上加的padding 总大小，即=paddingLeft+paddingRight
+ private int sectionEdgeVPaddingPx;
+ private Rect preRect = new Rect();
+ private boolean isPreItemHeader = false;
+ private int sectionStartItemPos = 0;
+ private int sectionEndItemPos = 0;
+ private int sectionItemCount = 0;
+
+ /**
+ * @param gapHorizontalDp 水平间距
+ * @param gapVerticalDp 垂直间距
+ * @param sectionEdgeHPaddingDp 左右两端的padding大小
+ * @param sectionEdgeVPaddingDp 上下两端的padding大小
+ */
+ public GridSectionAverageGapItemDecoration(float gapHorizontalDp, float gapVerticalDp, float sectionEdgeHPaddingDp, float sectionEdgeVPaddingDp) {
+ this.gapHorizontalDp = gapHorizontalDp;
+ this.gapVerticalDp = gapVerticalDp;
+ this.sectionEdgeHPaddingDp = sectionEdgeHPaddingDp;
+ this.sectionEdgeVPaddingDp = sectionEdgeVPaddingDp;
+ }
+
+ @Override
+ public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
+ if (parent.getLayoutManager() instanceof GridLayoutManager && parent.getAdapter() instanceof BaseSectionQuickAdapter) {
+ GridLayoutManager layoutManager = (GridLayoutManager) parent.getLayoutManager();
+ BaseSectionQuickAdapter adapter = (BaseSectionQuickAdapter) parent.getAdapter();
+ int spanCount = layoutManager.getSpanCount();
+ int position = parent.getChildAdapterPosition(view);
+ SectionEntity entity = adapter.getItem(position);
+
+ if (entity != null && entity.isHeader) {
+ //不处理header
+ isPreItemHeader = true;
+ outRect.set(0,0,0,0);
+// Log.w("GridAverageGapItem", "pos=" + position + "," + outRect.toShortString());
+ return;
+ }
+
+ if (isPreItemHeader) {
+ sectionStartItemPos = position;
+ sectionEndItemPos = findSectionLastItemPos(position, adapter);
+ sectionItemCount = sectionEndItemPos - sectionStartItemPos + 1;
+// Log.w("GridAverageGapItem", "new section=" + sectionStartItemPos + "-" + sectionEndItemPos);
+ }
+
+ if (gapHSizePx < 0 || gapVSizePx < 0) {
+ transformGapDefinition(parent, spanCount);
+ }
+ outRect.top = gapVSizePx;
+ outRect.bottom = 0;
+
+ //下面的visualPos为单个Section内的视觉Pos
+ int visualPos = position + 1 - sectionStartItemPos;
+ if (visualPos % spanCount == 1) {
+ //第一列
+ outRect.left = sectionEdgeHPaddingPx;
+ outRect.right = eachItemHPaddingPx - sectionEdgeHPaddingPx;
+ } else if (visualPos % spanCount == 0) {
+ //最后一列
+ outRect.left = eachItemHPaddingPx - sectionEdgeHPaddingPx;
+ outRect.right = sectionEdgeHPaddingPx;
+ } else {
+ outRect.left = gapHSizePx - preRect.right;
+ outRect.right = eachItemHPaddingPx - outRect.left;
+ }
+
+ if (visualPos - spanCount <= 0) {
+ //每个section的第一行
+ outRect.top = sectionEdgeVPaddingPx;
+ }
+ //存在即是第一行，又是最后一行的情况，故不用elseif
+ if (isLastRow(visualPos, spanCount, sectionItemCount)) {
+ //每个section的最后一行
+ outRect.bottom = sectionEdgeVPaddingPx;
+ }
+ preRect = new Rect(outRect);
+ isPreItemHeader = false;
+// Log.w("GridAverageGapItem", "pos=" + position + "," + outRect.toShortString());
+ } else {
+ super.getItemOffsets(outRect, view, parent, state);
+ }
+ }
+
+ private void transformGapDefinition(RecyclerView parent, int spanCount) {
+ DisplayMetrics displayMetrics = new DisplayMetrics();
+ parent.getDisplay().getMetrics(displayMetrics);
+ gapHSizePx = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, gapHorizontalDp, displayMetrics);
+ gapVSizePx = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, gapVerticalDp, displayMetrics);
+ sectionEdgeHPaddingPx = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, sectionEdgeHPaddingDp, displayMetrics);
+ sectionEdgeVPaddingPx = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, sectionEdgeVPaddingDp, displayMetrics);
+ eachItemHPaddingPx = (sectionEdgeHPaddingPx * 2 + gapHSizePx * (spanCount - 1)) / spanCount;
+ }
+
+ private int findSectionLastItemPos(int curPos, BaseQuickAdapter adapter) {
+ int count = adapter.getItemCount();
+ if (count == curPos + 1) {
+ return curPos;
+ }
+ SectionEntity sectionEntity = null;
+ for (int i = curPos + 1; i < count; i++) {
+ sectionEntity = adapter.getItem(i);
+ if (sectionEntity != null && sectionEntity.isHeader) {
+ return i - 1;
+ }
+ }
+ return count - 1;
+ }
+
+ private boolean isLastRow(int visualPos, int spanCount, int sectionItemCount) {
+ int lastRowCount = sectionItemCount % spanCount;
+ lastRowCount = lastRowCount == 0 ? spanCount : lastRowCount;
+ return visualPos > sectionItemCount - lastRowCount;
+ }
+}
diff --git a/app/src/main/res/layout/item_section_content.xml b/app/src/main/res/layout/item_section_content.xml
index c6d9ba0c1..4d072f82d 100644
--- a/app/src/main/res/layout/item_section_content.xml
+++ b/app/src/main/res/layout/item_section_content.xml
@@ -6,8 +6,6 @@
android:layout_width="match_parent"
android:layout_height="150dp"
android:layout_gravity="center"
- android:layout_marginLeft="5dp"
- android:layout_marginRight="5dp"
android:foreground="?android:attr/selectableItemBackground"
card_view:cardBackgroundColor="@android:color/white"
card_view:cardCornerRadius="4dp"