本文主要是介绍实现监听NestedScrollView拖拽、惯性滑动、滑动停止、滑动到顶部和底部,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
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
@Overridepublic 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() {@Overridepublic 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() {@Overridepublic void run() {if (addScrollChangeListener!=null){addScrollChangeListener.onScrollState(ScrollState.IDLE);}}});}else {handler.post(new Runnable() {@Overridepublic 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
@Overridepublic 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
@Overrideprotected 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() ;}@Overridepublic 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());}@Overridepublic 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 ;}}@Overrideprotected 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;}@Overridepublic 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() {@Overridepublic 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() {@Overridepublic void run() {if (addScrollChangeListener!=null){addScrollChangeListener.onScrollState(ScrollState.IDLE);}}});}else {handler.post(new Runnable() {@Overridepublic 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 {@Overridepublic void onScrollChange(int scrollX, int scrollY, int oldScrollX, int oldScrollY) {}@Overridepublic 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;}}}
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