From 6bba64384fe1da6d4c7e5ebe915913659127db29 Mon Sep 17 00:00:00 2001
From: 3440395 <1152433972@qq.com>
Date: Thu, 9 Feb 2017 23:17:10 +0800
Subject: [PATCH] Update FlowLayoutManager.java
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修复当item不足一页时，上滑，item乱跳的bug
---
 .../layoutmanager/flow/FlowLayoutManager.java       | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/layoutmanager/src/main/java/com/mcxtzhang/layoutmanager/flow/FlowLayoutManager.java b/layoutmanager/src/main/java/com/mcxtzhang/layoutmanager/flow/FlowLayoutManager.java
index fbcaa29..6ab66c4 100644
--- a/layoutmanager/src/main/java/com/mcxtzhang/layoutmanager/flow/FlowLayoutManager.java
+++ b/layoutmanager/src/main/java/com/mcxtzhang/layoutmanager/flow/FlowLayoutManager.java
@@ -165,7 +165,10 @@ private int fill(RecyclerView.Recycler recycler, RecyclerView.State state, int d
             }
             //添加完后，判断是否已经没有更多的ItemView，并且此时屏幕仍有空白，则需要修正dy
             View lastChild = getChildAt(getChildCount() - 1);
-            if (getPosition(lastChild) == getItemCount() - 1) {
+            
+            View firstVisibleChild = getChildAt(0);
+            //要做底部修复，还要满足下面第一个条件：第一个显示的View的top在屏幕之外
+            if (firstVisibleChild.getTop() < 0 && getPosition(lastChild) == getItemCount() - 1) {
                 int gap = getHeight() - getPaddingBottom() - getDecoratedBottom(lastChild);
                 if (gap > 0) {
                     dy -= gap;
@@ -227,9 +230,13 @@ public int scrollVerticallyBy(int dy, RecyclerView.Recycler recycler, RecyclerVi
             View lastChild = getChildAt(getChildCount() - 1);
             if (getPosition(lastChild) == getItemCount() - 1) {
                 int gap = getHeight() - getPaddingBottom() - getDecoratedBottom(lastChild);
-                if (gap > 0) {
+                
+                
+                View firstVisibleChild = getChildAt(0);
+                //当前显示的第一个View的top小于零，说明该recyclerview发生了滚动，可以做底部修复
+                if (gap > 0 && firstVisibleChild.getTop() < 0) {
                     realOffset = -gap;
-                } else if (gap == 0) {
+                } else if (gap == 0 || firstVisibleChild.getTop() >= 0) {//当前第一个显示的top大于等于0，并且最后一个显示的就是最后一个，那一定不需要滚动了，即使gap！=0，也不需要修复
                     realOffset = 0;
                 } else {
                     realOffset = Math.min(realOffset, -gap);