安卓Activity上滑关闭效果实现

最近在做一个屏保功能，需要支持如图的上滑关闭功能。

因为屏保是可以左右滑动切换的，内部是一个viewpager

做这个效果的时候，关键就是要注意外层拦截触摸事件时，需要有条件的拦截，不能影响到内部viewpager的滑动处理。

以下是封装好的自定义view，继承自FrameLayout：

import android.animation.Animator;
import android.animation.ObjectAnimator;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.widget.FrameLayout;import androidx.annotation.NonNull;public class SlideCloseFrameLayout extends FrameLayout {/*** 滑动监听器*/public interface OnSlideCloseListener {/*** 滑动开始时调用*/void onStartSlide();/*** 滑动结束&动画结束时调用，isClose为true表示滑动关闭，为false表示滑动恢复原位* @param isClose*/void onStopSlide(boolean isClose);}private OnSlideCloseListener onSlideCloseListener;private static final String TAG = "SlideCloseFrameLayout";private float downY = 0; // 记录手指按下时的Y坐标private boolean isSlideAction = false; // 标记是否为滑动关闭动作private VelocityTracker velocityTracker = null; // 速度跟踪器private float lastTranslationY = 0; // 记录上一次的TranslationY值，用于滑动时的位置更新public SlideCloseFrameLayout(Context context) {super(context);}public SlideCloseFrameLayout(Context context, AttributeSet attrs) {super(context, attrs);}public SlideCloseFrameLayout(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);}@Overridepublic boolean onInterceptTouchEvent(MotionEvent event) {try {int action = event.getAction();switch (action) {case MotionEvent.ACTION_DOWN:downY = event.getRawY();if (downY > getHeight() - getHeight() / 5f) {initVelocityTracker();velocityTracker.addMovement(event);return false; // 拦截事件}break;case MotionEvent.ACTION_MOVE:velocityTracker.addMovement(event);velocityTracker.computeCurrentVelocity(1000);float xVelocity = velocityTracker.getXVelocity();float yVelocity = velocityTracker.getYVelocity();if (Math.abs(yVelocity) > ViewConfiguration.get(getContext()).getScaledMinimumFlingVelocity()&& Math.abs(yVelocity) > Math.abs(xVelocity)) {// 如果超过最小判定距离，并且Y轴速度大于X轴速度，才视为纵向滑动if (yVelocity < 0) {// 向下滑动if (onSlideCloseListener != null) {onSlideCloseListener.onStartSlide();}isSlideAction = true;return true;}}break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_CANCEL:isSlideAction = false;break;}} catch (Exception e) {e.printStackTrace();}return super.onInterceptTouchEvent(event);}@Overridepublic boolean onTouchEvent(MotionEvent event) {try {if (isSlideAction) {velocityTracker.addMovement(event);int action = event.getAction();switch (action) {case MotionEvent.ACTION_MOVE:float moveDistance = event.getRawY() - downY;if (moveDistance < 0) { // 仅当向上滑动时处理lastTranslationY = moveDistance;this.setTranslationY(moveDistance);}break;case MotionEvent.ACTION_UP:case MotionEvent.ACTION_CANCEL:velocityTracker.computeCurrentVelocity(1000);float velocityY = velocityTracker.getYVelocity();if (Math.abs(velocityY) > 1000 || Math.abs(lastTranslationY) > getHeight() / 5f) {slideUpAndExit();} else {slideBack();}releaseVelocityTracker();isSlideAction = false;break;}return true;}} catch (Exception e) {e.printStackTrace();}return super.onTouchEvent(event);}public boolean isSlideAction() {return isSlideAction;}public OnSlideCloseListener getOnSlideCloseListener() {return onSlideCloseListener;}public void setOnSlideCloseListener(OnSlideCloseListener onSlideCloseListener) {this.onSlideCloseListener = onSlideCloseListener;}private void initVelocityTracker() {if (velocityTracker == null) {velocityTracker = VelocityTracker.obtain();} else {velocityTracker.clear();}}private void releaseVelocityTracker() {if (velocityTracker != null) {velocityTracker.recycle();velocityTracker = null;}}private void slideUpAndExit() {// 执行上移退出动画TranslateAnimation exitAnimation = new TranslateAnimation(0, 0, getTranslationY(), -getHeight());exitAnimation.setDuration(300);exitAnimation.setFillAfter(false);exitAnimation.setAnimationListener(new Animation.AnimationListener() {@Overridepublic void onAnimationStart(Animation animation) {}@Overridepublic void onAnimationEnd(Animation animation) {// 动画结束后的操作setVisibility(View.GONE); // 隐藏或其他逻辑if (onSlideCloseListener != null) {onSlideCloseListener.onStopSlide(true);}}@Overridepublic void onAnimationRepeat(Animation animation) {}});startAnimation(exitAnimation);this.setTranslationY(0); // 重置TranslationY值}private void slideBack() {// 使用属性动画使视图回到原位ObjectAnimator animator = ObjectAnimator.ofFloat(this, "translationY", getTranslationY(), 0);animator.setDuration(300);animator.start();animator.addListener(new Animator.AnimatorListener(){@Overridepublic void onAnimationStart(@NonNull Animator animation) {}@Overridepublic void onAnimationEnd(@NonNull Animator animation) {if (onSlideCloseListener != null) {onSlideCloseListener.onStopSlide(false);}}@Overridepublic void onAnimationCancel(@NonNull Animator animation) {if (onSlideCloseListener != null) {onSlideCloseListener.onStopSlide(false);}}@Overridepublic void onAnimationRepeat(@NonNull Animator animation) {}});}
}

Activity使用时，只需要把根View设置为这个自定义view，然后透明主题，透明背景，同时关闭Activity的进入退出动画，便可以实现如图效果了。

嵌套使用时，不会影响到内部的Viewpager或其他可滑动view