实现监听NestedScrollView拖拽、惯性滑动、滑动停止、滑动到顶部和底部
运行实时监听日志：
因为在开发中经常会需要在滚动的各种状态下处理一些UI界面功能，但是系统又没有提供实时监听拖拽、惯性滑动、滑动停止、滑动到顶部和底部等功能。那怎么办，只能自己去实现这些功能。
- 滚动的几种状态
/**
* 滚动状态
*/
public enum ScrollState{
DRAG, // 拖拽中
SCROLLING, // 正在滚动
IDLE // 已停止
}
- 回调方法
public interface AddScrollChangeListener{
/**
* 滚动监听
* @param scrollX
* @param scrollY
* @param oldScrollX
* @param oldScrollY
*/
void onScrollChange( int scrollX, int scrollY, int oldScrollX, int oldScrollY);
/**
* 滚动状态
*
* @param state
*/
void onScrollState(ScrollState state);
}
重写 public boolean onTouchEvent(MotionEvent ev)实现 监听拖拽、监听惯性滑动、监听滑动停止
- 监听拖拽
- 监听惯性滑动
- 监听滑动停止
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()){
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_MOVE:
isStart = false ;
LogUtils.LOG_V("[NewNestedScrollView]->DRAG 拖拽中");
if (addScrollChangeListener!=null){
addScrollChangeListener.onScrollState(ScrollState.DRAG);
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_OUTSIDE:
case MotionEvent.ACTION_UP:
isStart = true ;
start();
break;
}
return super.onTouchEvent(ev);
}
/**
*
* 开始计算是否停止还是正在滚性滑动
*
*/
private void start() {
new Thread(new Runnable() {
@Override
public void run() {
while (isStart){
if ((System.currentTimeMillis() - lastTime)>50){
int newScrollY = getScrollY();
lastTime = System.currentTimeMillis();
if (newScrollY - lastScrollY == 0){
isStart = false ;
LogUtils.LOG_V("[NewNestedScrollView]->IDLE 停止滚动");
handler.post(new Runnable() {
@Override
public void run() {
if (addScrollChangeListener!=null){
addScrollChangeListener.onScrollState(ScrollState.IDLE);
}
}
});
}else {
handler.post(new Runnable() {
@Override
public void run() {
LogUtils.LOG_V("[NewNestedScrollView]->SCROLLING 正在滚动中");
if (isStart&&addScrollChangeListener!=null){
addScrollChangeListener.onScrollState(ScrollState.SCROLLING );
}
}
});
}
lastScrollY = newScrollY;
}
}
}
}).start();
}
- 监听滑动到顶部
@Override
public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
if (getScrollY()<=0){
LogUtils.LOG_V("[NewNestedScrollView]->onScrollChange = top");
top = true ;
}else {
top = false ;
}
}
- 监听底部 （首先需要知道整个滚动内容的高度和当前滚动控件view的高度）从写onMeasure（）测量测试高度
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
totalHeight = 0 ;
int count = getChildCount();
for (int i =0 ;i < count ;i++){
View view = getChildAt(i);
totalHeight += view.getMeasuredHeight();
}
viewHeight = getHeight() ;
}
@Override
public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
if (totalHeight>viewHeight && (totalHeight - viewHeight) == scrollY){
LogUtils.LOG_V("[NewNestedScrollView]->onScrollChange = bottom");
bottom = true ;
}else {
bottom = false ;
}
}
完整代码列子
import android.content.Context;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.widget.NestedScrollView;
public class NewNestedScrollView extends NestedScrollView implements NestedScrollView.OnScrollChangeListener {
/**
*
*/
private AddScrollChangeListener addScrollChangeListener;
/**
* 滚动状态
*/
public enum ScrollState{
DRAG, // 拖拽中
SCROLLING, // 正在滚动
IDLE // 已停止
}
/**
*
* 记录上一次滑动
*
*/
private int lastScrollY ;
/**
*/
private boolean isStart = false ;
/**
* 上一次记录的时间
*/
private long lastTime ;
private Handler handler;
/**
* 整個滾動内容高度
*
*/
public int totalHeight = 0 ;
/**
*
* 当前view的高度
*
*/
public int viewHeight = 0 ;
/**
* 是否滚动到底了
*/
private boolean bottom = false;
/**
* 是否滚动在顶部
*
* @param context
*/
private boolean top = false ;
public NewNestedScrollView(@NonNull Context context) {
this(context,null);
}
public NewNestedScrollView(@NonNull Context context, @Nullable AttributeSet attrs) {
this(context, attrs,0);
}
public NewNestedScrollView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
setOnScrollChangeListener(this);
handler = new Handler(context.getMainLooper());
}
@Override
public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
/*实时滚动回调*/
if (addScrollChangeListener!=null){
addScrollChangeListener.onScrollChange( scrollX, scrollY, oldScrollX, oldScrollY);
}
if (totalHeight>viewHeight && (totalHeight - viewHeight) == scrollY){
LogUtils.LOG_V("[NewNestedScrollView]->onScrollChange = bottom");
bottom = true ;
}else {
bottom = false ;
}
if (getScrollY()<=0){
LogUtils.LOG_V("[NewNestedScrollView]->onScrollChange = top");
top = true ;
}else {
top = false ;
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
totalHeight = 0 ;
int count = getChildCount();
for (int i =0 ;i < count ;i++){
View view = getChildAt(i);
totalHeight += view.getMeasuredHeight();
}
viewHeight = getHeight() ;
}
/**
* 是否动到底
* @return
*/
public boolean isBottom(){
return bottom;
}
/**
* 是否滚动到了 顶部
*
* @return
*/
public boolean isTop(){
return top;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()){
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_MOVE:
isStart = false ;
LogUtils.LOG_V("[NewNestedScrollView]->DRAG 拖拽中");
if (addScrollChangeListener!=null){
addScrollChangeListener.onScrollState(ScrollState.DRAG);
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_OUTSIDE:
case MotionEvent.ACTION_UP:
isStart = true ;
start();
break;
}
return super.onTouchEvent(ev);
}
/**
*
* 开始计算是否停止还是正在滚性滑动
*
*/
private void start() {
new Thread(new Runnable() {
@Override
public void run() {
/**
* 表示已停止
*/
while (isStart){
if ((System.currentTimeMillis() - lastTime)>50){
int newScrollY = getScrollY();
lastTime = System.currentTimeMillis();
if (newScrollY - lastScrollY == 0){
isStart = false ;
LogUtils.LOG_V("[NewNestedScrollView]->IDLE 停止滚动");
handler.post(new Runnable() {
@Override
public void run() {
if (addScrollChangeListener!=null){
addScrollChangeListener.onScrollState(ScrollState.IDLE);
}
}
});
}else {
handler.post(new Runnable() {
@Override
public void run() {
LogUtils.LOG_V("[NewNestedScrollView]->SCROLLING 正在滚动中");
if (isStart&&addScrollChangeListener!=null){
addScrollChangeListener.onScrollState(ScrollState.SCROLLING );
}
}
});
}
lastScrollY = newScrollY;
}
}
}
}).start();
}
/**
* 设置监听
*
* @param addScrollChangeListener
* @return
*/
public NewNestedScrollView addScrollChangeListener(AddScrollChangeListener addScrollChangeListener) {
this.addScrollChangeListener = addScrollChangeListener;
return this ;
}
public interface AddScrollChangeListener{
/**
* 滚动监听
* @param scrollX
* @param scrollY
* @param oldScrollX
* @param oldScrollY
*/
void onScrollChange( int scrollX, int scrollY, int oldScrollX, int oldScrollY);
/**
* 滚动状态
*
* @param state
*/
void onScrollState(ScrollState state);
}
}
如何使用
private class NewOnScroll implements NewNestedScrollView.AddScrollChangeListener {
@Override
public void onScrollChange(int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
}
@Override
public void onScrollState(NewNestedScrollView.ScrollState state) {
MainActivity activity = (MainActivity) getActivity();
switch (state){
case DRAG:
case SCROLLING:
activity.anim(Util.screenWidth()-Util.dp2Px(30));
activity.alpha(0.4f);
break;
case IDLE:
activity.anim(Util.screenWidth()-Util.dp2Px(70));
activity.alpha(1f);
break;
}
}
}