Android linearLayoutmaneger.findLastCompletelyVisibleItemPosition在coordinatorLayout中返回错误的值
我在coordinatorLayout中有一个recyclerView,我想从中获取最后一个可见项:Android linearLayoutmaneger.findLastCompletelyVisibleItemPosition在coordinatorLayout中返回错误的值,android,android-coordinatorlayout,android-appbarlayout,Android,Android Coordinatorlayout,Android Appbarlayout,我在coordinatorLayout中有一个recyclerView,我想从中获取最后一个可见项: <?xml version="1.0" encoding="utf-8"?><android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/re
<?xml version="1.0" encoding="utf-8"?><android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbarLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/colorPrimary"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
>
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/main.collapsing"
android:layout_width="match_parent"
android:layout_height="100dp"
android:background="#f00"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v7.widget.RecyclerView
android:scrollbars="none"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/lastVisibleItem"
android:text="last position"
/>
</android.support.design.widget.CoordinatorLayout>
问题出在start findLastCompletelyVisibleItemPosition()方法返回中,例如,14是错误的,12是正确的,在我向下滚动到项目14之后,findLastCompletelyVisibleItemPosition()再次返回14。我知道这是由于AppBarLayout和CoordinatorLayout造成的,但我无法找到正确的方法来确定最后一个完整可见的项目位置。我已设法找到解决此问题的方法 您应该为RecyclerView使用自定义LayoutManager,并覆盖查找第一个和最后一个位置的方法
public final class FixedForAppBarLayoutManager extends LinearLayoutManager {
public FixedForAppBarLayoutManager(final Context context, final AttributeSet attrs, final int defStyleAttr, final int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
public FixedForAppBarLayoutManager(final Context context, final int spanCount) {
super(context, spanCount);
}
public FixedForAppBarLayoutManager(final Context context, final int spanCount, final int orientation, final boolean reverseLayout) {
super(context, spanCount, orientation, reverseLayout);
}
@Override
public int findFirstVisibleItemPosition() {
final View item = findVisibleItem(0, getChildCount(), false);
return item == null ? -1 : getPosition(item);
}
@Override
public int findFirstCompletelyVisibleItemPosition() {
final View item = findVisibleItem(0, getChildCount(), true);
return item == null ? -1 : getPosition(item);
}
@Override
public int findLastVisibleItemPosition() {
final View item = findVisibleItem(getChildCount() - 1, -1, false);
return item == null ? -1 : getPosition(item);
}
@Override
public int findLastCompletelyVisibleItemPosition() {
final View item = findVisibleItem(getChildCount() - 1, -1, true);
return item == null ? -1 : getPosition(item);
}
private View findVisibleItem(final int fromIndex, final int toIndex, final boolean isCompletely) {
final int next = toIndex > fromIndex ? 1 : -1;
for (int i = fromIndex; i != toIndex; i += next) {
final View child = getChildAt(i);
if (checkIsVisible(child, isCompletely)) {
return child;
}
}
return null;
}
private boolean checkIsVisible(final View child, final boolean isCompletely) {
final int[] location = new int[2];
child.getLocationOnScreen(location);
final View parent = (View) child.getParent();
final Rect parentRect = new Rect();
parent.getGlobalVisibleRect(parentRect);
if (getOrientation() == HORIZONTAL) {
final int childLeft = location[0];
final int childRight = location[0] + child.getWidth();
return isCompletely
? childLeft >= parentRect.left && childRight <= parentRect.right
: childLeft <= parentRect.right && childRight >= parentRect.left;
} else {
final int childTop = location[1];
final int childBottom = location[1] + child.getHeight();
return isCompletely
? childTop >= parentRect.top && childBottom <= parentRect.bottom
: childTop <= parentRect.bottom && childBottom >= parentRect.top;
}
}
AppBarLayoutManager修复的公共最终类扩展了LinearLayoutManager{
public FixedForAppBarLayoutManager(最终上下文上下文、最终属性集属性、最终int defStyleAttr、最终int defStyleRes){
super(context、attrs、defStyleAttr、defStyleRes);
}
public FixedForAppBarLayoutManager(最终上下文,最终整数span计数){
super(上下文、spanCount);
}
public Fixed for AppBarLayoutManager(最终上下文上下文、最终整数跨距计数、最终整数方向、最终布尔反转){
超级(上下文、跨距计数、方向、反转);
}
@凌驾
public int findFirstVisibleItemPosition(){
最终视图项=findVisibleItem(0,getChildCount(),false);
返回项==null?-1:getPosition(项);
}
@凌驾
public int findFirstCompletelyVisibleItemPosition(){
最终视图项=findVisibleItem(0,getChildCount(),true);
返回项==null?-1:getPosition(项);
}
@凌驾
public int findLastVisibleItemPosition(){
最终视图项=findVisibleItem(getChildCount()-1,-1,false);
返回项==null?-1:getPosition(项);
}
@凌驾
public int findLastCompletelyVisibleItemPosition(){
最终视图项=findVisibleItem(getChildCount()-1,-1,true);
返回项==null?-1:getPosition(项);
}
私有视图findVisibleItem(final int from index,final int to index,final boolean是完全的){
最终整数next=toIndex>fromIndex?1:-1;
for(int i=fromIndex;i!=toIndex;i+=next){
最终视图子对象=getChildAt(i);
如果(检查是否可见(子项,是否完全)){
返回儿童;
}
}
返回null;
}
私有布尔值检查可见(最终视图子项,最终布尔值完整){
最终整数[]位置=新整数[2];
child.getLocationOnScreen(位置);
最终视图parent=(视图)child.getParent();
final Rect parentRect=new Rect();
getGlobalVisibleRect(parentRect);
如果(getOrientation()==水平){
final int childLeft=位置[0];
final int childRight=位置[0]+child.getWidth();
完全返回
?childLeft>=parentRect.left&&childRight=parentRect.top&&childBottom下面的答案很有魅力!也许对某些人来说,kotlin变体可能有用:
import android.content.Context
import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.LinearLayoutManager
class FixedForAppBarLayoutManager(context: Context?) : LinearLayoutManager(context) {
override fun findFirstVisibleItemPosition(): Int {
val item: View? = findVisibleItem(0, childCount, false)
return if (item == null) -1 else getPosition(item)
}
override fun findFirstCompletelyVisibleItemPosition(): Int {
val item: View? = findVisibleItem(0, childCount, true)
return if (item == null) -1 else getPosition(item)
}
override fun findLastVisibleItemPosition(): Int {
val item: View? = findVisibleItem(childCount - 1, -1, false)
return if (item == null) -1 else getPosition(item)
}
override fun findLastCompletelyVisibleItemPosition(): Int {
val item: View? = findVisibleItem(childCount - 1, -1, true)
return if (item == null) -1 else getPosition(item)
}
private fun findVisibleItem(
fromIndex: Int,
toIndex: Int,
isCompletely: Boolean
): View? {
val next = if (toIndex > fromIndex) 1 else -1
var i = fromIndex
while (i != toIndex) {
val child: View? = getChildAt(i)
child?.let {
if (checkIsVisible(child, isCompletely)) {
return child
}
i += next
}
}
return null
}
private fun checkIsVisible(child: View, isCompletely: Boolean): Boolean {
val location = IntArray(2)
child.getLocationOnScreen(location)
val parent: View = child.parent as View
val parentRect = Rect()
parent.getGlobalVisibleRect(parentRect)
return if (orientation == HORIZONTAL) {
val childLeft = location[0]
val childRight: Int = location[0] + child.width
if (isCompletely) {
childLeft >= parentRect.left && childRight <= parentRect.right
} else {
childLeft <= parentRect.right && childRight >= parentRect.left
}
} else {
val childTop = location[1]
val childBottom: Int = location[1] + child.height
if (isCompletely) {
childTop >= parentRect.top && childBottom <= parentRect.bottom
} else {
childTop <= parentRect.bottom && childBottom >= parentRect.top
}
}
}
}
导入android.content.Context
导入android.graphics.Rect
导入android.view.view
导入androidx.recyclerview.widget.LinearLayoutManager
类FixedForAppBarLayoutManager(上下文:上下文?):LinearLayoutManager(上下文){
重写findFirstVisibleItemPosition():Int{
val项目:视图?=findVisibleItem(0,childCount,false)
返回if(item==null)-1 else getPosition(item)
}
重写fun findFirstCompletelyVisibleItemPosition():Int{
val项:视图?=findVisibleItem(0,childCount,true)
返回if(item==null)-1 else getPosition(item)
}
重写fun findLastVisibleItemPosition():Int{
val项:视图?=findVisibleItem(childCount-1,-1,false)
返回if(item==null)-1 else getPosition(item)
}
重写fun findLastCompletelyVisibleItemPosition():Int{
val项:视图?=findVisibleItem(childCount-1,-1,真)
返回if(item==null)-1 else getPosition(item)
}
私人娱乐查找可视项目(
fromIndex:Int,
toIndex:Int,
完全:布尔型
):查看{
val next=if(toIndex>fromIndex)1 else-1
var i=原始指数
而(i!=toIndex){
val child:View?=getChildAt(i)
孩子?让我来{
如果(检查是否可见(子项,是否完全)){
返回儿童
}
i+=下一个
}
}
返回空
}
private-fun-checkIsVisible(子:视图,iscompletly:Boolean):布尔{
val位置=阵列(2)
child.getLocationOnScreen(位置)
val parent:View=child.parent作为视图
val parentRect=Rect()
parent.getGlobalVisibleRect(parentRect)
如果返回(方向==水平){
val childLeft=位置[0]
val childRight:Int=位置[0]+child.width
如果(完全){
childLeft>=parentRect.left&&childRight=parentRect.top&&childBottom
import android.content.Context
import android.graphics.Rect
import android.view.View
import androidx.recyclerview.widget.LinearLayoutManager
class FixedForAppBarLayoutManager(context: Context?) : LinearLayoutManager(context) {
override fun findFirstVisibleItemPosition(): Int {
val item: View? = findVisibleItem(0, childCount, false)
return if (item == null) -1 else getPosition(item)
}
override fun findFirstCompletelyVisibleItemPosition(): Int {
val item: View? = findVisibleItem(0, childCount, true)
return if (item == null) -1 else getPosition(item)
}
override fun findLastVisibleItemPosition(): Int {
val item: View? = findVisibleItem(childCount - 1, -1, false)
return if (item == null) -1 else getPosition(item)
}
override fun findLastCompletelyVisibleItemPosition(): Int {
val item: View? = findVisibleItem(childCount - 1, -1, true)
return if (item == null) -1 else getPosition(item)
}
private fun findVisibleItem(
fromIndex: Int,
toIndex: Int,
isCompletely: Boolean
): View? {
val next = if (toIndex > fromIndex) 1 else -1
var i = fromIndex
while (i != toIndex) {
val child: View? = getChildAt(i)
child?.let {
if (checkIsVisible(child, isCompletely)) {
return child
}
i += next
}
}
return null
}
private fun checkIsVisible(child: View, isCompletely: Boolean): Boolean {
val location = IntArray(2)
child.getLocationOnScreen(location)
val parent: View = child.parent as View
val parentRect = Rect()
parent.getGlobalVisibleRect(parentRect)
return if (orientation == HORIZONTAL) {
val childLeft = location[0]
val childRight: Int = location[0] + child.width
if (isCompletely) {
childLeft >= parentRect.left && childRight <= parentRect.right
} else {
childLeft <= parentRect.right && childRight >= parentRect.left
}
} else {
val childTop = location[1]
val childBottom: Int = location[1] + child.height
if (isCompletely) {
childTop >= parentRect.top && childBottom <= parentRect.bottom
} else {
childTop <= parentRect.bottom && childBottom >= parentRect.top
}
}
}
}