1+ package com.ooftf.vertical.nested
2+
3+ import android.content.Context
4+ import android.os.Build
5+ import android.support.annotation.RequiresApi
6+ import android.support.v4.view.NestedScrollingParent2
7+ import android.support.v4.view.NestedScrollingParentHelper
8+ import android.support.v4.view.PagerAdapter
9+ import android.util.AttributeSet
10+ import android.util.Log
11+ import android.view.MotionEvent
12+ import android.view.View
13+ import android.widget.FrameLayout
14+ import android.widget.Scroller
15+
16+
17+ /* *
18+ * 高仿淘宝商品页上下分页布局
19+ * Created by master on 2016/3/28.
20+ */
21+ class VerticalPagerLayout : FrameLayout , NestedScrollingParent2 {
22+ var helper = NestedScrollingParentHelper (this )
23+ override fun onNestedPreScroll (target : View , dx : Int , dy : Int , consumed : IntArray? , type : Int ) {
24+ moved = true
25+ Log .e(" onNestedPreScroll" " dy::" + dy)
26+ if (scrollY % height != 0 ) {
27+ scrollBy(0 , dy)
28+ consumed?.set(1 , dy)
29+ }
30+ }
31+
32+ override fun onStopNestedScroll (target : View , type : Int ) {
33+ helper.onStopNestedScroll(target, type)
34+ Log .e(" onStopNestedScroll" " onStopNestedScroll"
35+ judgePage(true )
36+ }
37+
38+ override fun onStartNestedScroll (child : View , target : View , axes : Int , type : Int ): Boolean {
39+ mScroller.forceFinished(true )
40+ Log .e(" onStartNestedScroll" " onStartNestedScroll"
41+ moved = false
42+ return true
43+ }
44+
45+ override fun onNestedScrollAccepted (child : View , target : View , axes : Int , type : Int ) {
46+ Log .e(" onNestedScrollAccepted" " onNestedScrollAccepted"
47+ helper.onNestedScrollAccepted(child, target, axes, type)
48+ }
49+
50+ var moved = false
51+ override fun onNestedScroll (target : View , dxConsumed : Int , dyConsumed : Int , dxUnconsumed : Int , dyUnconsumed : Int , type : Int ) {
52+ Log .e(" onNestedScroll" " dyConsumed::" + dyConsumed + " ,dyUnconsumed::" + dyUnconsumed)
53+ scrollBy(0 , dyUnconsumed)
54+ }
55+
56+
57+ /* *
58+ * 松开时布局滑动动画时间
59+ */
60+ private var SCROLL_DURATION = 700
61+
62+ var offscreenPageLimit = 1 ;
63+ private var mScroller: Scroller
64+ private var items = ArrayList <ItemInfo >()
65+ var adapter: PagerAdapter ? = null
66+ set(value) {
67+ field = value
68+ resetLayout()
69+ }
70+
71+ override fun onInterceptHoverEvent (event : MotionEvent ? ): Boolean {
72+ Log .e(" onInterceptHoverEvent" " ..."
73+ return super .onInterceptHoverEvent(event)
74+ }
75+
76+ /* *
77+ * 当更换adapter之后，重置所有信息
78+ */
79+ private fun resetLayout () {
80+ removeAllItem()
81+ scrollTo(0 , 0 )
82+ refreshViews()
83+ }
84+
85+ constructor (context: Context ) : super (context)
86+
87+
88+ constructor (context: Context , attrs: AttributeSet ? ) : super (context, attrs)
89+
90+ constructor (context: Context , attrs: AttributeSet ? , defStyleAttr: Int ) : super (context, attrs, defStyleAttr)
91+
92+ @RequiresApi(api = Build .VERSION_CODES .LOLLIPOP )
93+ constructor (context: Context , attrs: AttributeSet ? , defStyleAttr: Int , defStyleRes: Int ) : super (context, attrs, defStyleAttr, defStyleRes)
94+
95+ init {
96+ mScroller = Scroller (context)
97+ }
98+
99+ /* *
100+ * 获取到点击事件的Page 如要是为了防止一次滑动翻超过一页
101+ */
102+ private var actionDownPage = 0
103+
104+
105+ override fun scrollTo (x : Int , y : Int ) {
106+ refreshViews()
107+ super .scrollTo(x, y)
108+ }
109+
110+ private fun refreshViews () {
111+ // 移除不必要View
112+ adapter ? : return
113+ adapter?.startUpdate(this )
114+ items
115+ .filter { it.position < getCurrentPage() - offscreenPageLimit || it.position > getCurrentPage() + offscreenPageLimit }
116+ .forEach {
117+ removeForItemInfo(it)
118+ }
119+ (getCurrentPage() - offscreenPageLimit.. getCurrentPage() + offscreenPageLimit).forEach {
120+ addNewView(it)
121+ }
122+ adapter?.setPrimaryItem(this , getCurrentPage(), itemInfoForPosition(getCurrentPage()).obj)
123+ adapter?.finishUpdate(this )
124+
125+ }
126+
127+ /* *
128+ * 移除所有的View
129+ */
130+ private fun removeAllItem () {
131+ adapter?.startUpdate(this )
132+ items.forEach {
133+ adapter?.destroyItem(this , it.position, it.obj)
134+ }
135+ items.clear()
136+ adapter?.finishUpdate(this )
137+ }
138+
139+ /* *
140+ * 根据ItemInfo 移除View
141+ */
142+ private fun removeForItemInfo (item : ItemInfo ) {
143+ adapter?.destroyItem(this , item.position, item.obj)
144+ items.remove(item)
145+ }
146+
147+ /* *
148+ * 根据位置信息 添加新的view
149+ */
150+ private fun addNewView (position : Int ) {
151+ if (position < 0 && position >= adapter!! .count) return
152+ items.forEach { if (it.position == position) return }
153+ items.add(ItemInfo (position, adapter!! .instantiateItem(this , position)))
154+ }
155+
156+ /* *
157+ * 获取到指定位置的View
158+ */
159+ private fun viewForPosition (position : Int ): View {
160+ val item = itemInfoForPosition(position)
161+ return viewForItemInfo(item)
162+ }
163+
164+ private fun viewForItemInfo (itemInfo : ItemInfo ): View {
165+ (0 until childCount).forEach {
166+ if (adapter!! .isViewFromObject(getChildAt(it), itemInfo.obj)) {
167+ return getChildAt(it)
168+ }
169+ }
170+ throw NullPointerException ()
171+ }
172+
173+ private fun itemInfoForPosition (position : Int ): ItemInfo {
174+ items.forEach {
175+ if (position == it.position) {
176+ return it
177+ }
178+ }
179+ throw NullPointerException ()
180+ }
181+
182+
183+ /* *
184+ * 判断应该停留在哪一页
185+ */
186+ private fun judgePage (smooth : Boolean ) {
187+ setCurrentItem(getCurrentPage(), smooth)
188+ }
189+
190+ /* *
191+ * 滚动到指定页面
192+ */
193+ fun setCurrentItem (page : Int , smooth : Boolean = true) {
194+ if (height == 0 ) {
195+ post { setCurrentItem(page, smooth) }
196+ return
197+ }
198+ if (smooth) {
199+ mScroller.startScroll(0 , scrollY, 0 , height * pageController(page) - scrollY, SCROLL_DURATION )
200+ invalidate()
201+ } else {
202+ scrollTo(0 , height * pageController(page))
203+ }
204+ }
205+
206+ /* *
207+ * 防止position超出边缘
208+ */
209+ private fun pageController (src : Int ): Int {
210+ if (src < 0 ) {
211+ return 0
212+ }
213+ return if (src > adapter!! .count - 1 ) {
214+ adapter!! .count - 1
215+ } else src
216+ }
217+
218+ /* *
219+ * 得到的是当前占有试图最大的页面
220+ */
221+ private fun getCurrentPage (): Int {
222+ if (height == 0 ) return 0
223+ return Math .round(scrollY.toFloat() / height)
224+ }
225+
226+ override fun onLayout (changed : Boolean , l : Int , t : Int , r : Int , b : Int ) {
227+ val height = b - t
228+ (0 until childCount).forEach {
229+ var itemInfo = itemInfoForView(getChildAt(it))
230+ getChildAt(it).layout(0 , itemInfo.position * height, r - l, (itemInfo.position + 1 ) * height)
231+ }
232+ }
233+
234+ private fun itemInfoForView (child : View ): ItemInfo {
235+ items.forEach {
236+ if (adapter!! .isViewFromObject(child, it.obj)) {
237+ return it
238+ }
239+ }
240+ throw NullPointerException ()
241+ }
242+
243+ override fun computeScroll () {
244+ if (mScroller.computeScrollOffset() && ! mScroller.isFinished) {
245+ scrollTo(mScroller.currX, mScroller.currY)
246+ postInvalidate()
247+ }
248+ }
249+
250+ /* fun getCurrentPage(): Int {
251+ if (height == 0) return 0
252+ return Math.round(scrollY.toFloat() / height)
253+ }*/
254+
255+ class ItemInfo (var position : Int , var obj : Any )
256+
257+
258+ }
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