这篇文章给大家介绍如何在Android界面中实现一个回弹效果,内容非常详细,感兴趣的小伙伴们可以参考借鉴,希望对大家能有所帮助。
具体代码如下所示:
public class MyScrollView extends ScrollView { private View childView; public MyScrollView(Context context) { super(context); } public MyScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } // @Override // protected void onLayout(boolean changed, int l, int t, int r, int b) { // super.onLayout(changed, l, t, r, b); // } //获取子视图 @Override protected void onFinishInflate() { super.onFinishInflate(); if (getChildCount() > 0) { childView = getChildAt(0); } } private int lastY;//上一次y轴方向操作的坐标位置 private Rect normal = new Rect();//用于记录临界状态的左、上、右、下 private boolean isFinishAnimation = true;//是否动画结束 private int lastX, downX, downY; //拦截:实现父视图对子视图的拦截 //是否拦截成功,取决于方法的返回值。返回值true:拦截成功。反之,拦截失败 @Override public boolean onInterceptTouchEvent(MotionEvent ev) { boolean isIntercept = false; int eventX = (int) ev.getX(); int eventY = (int) ev.getY(); switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: lastX = downX = eventX; lastY = downY = eventY; break; case MotionEvent.ACTION_MOVE: //获取水平和垂直方向的移动距离 int absX = Math.abs(eventX - downX); int absY = Math.abs(eventY - downY); if(absY > absX && absY >= UIUtils.dp2px(10)){ isIntercept = true;//执行拦截 } lastX = eventX; lastY = eventY; break; } return isIntercept; } @Override public boolean onTouchEvent(MotionEvent ev) { if (childView == null || !isFinishAnimation) { return super.onTouchEvent(ev); } int eventY = (int) ev.getY();//获取当前的y轴坐标 switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: lastY = eventY; break; case MotionEvent.ACTION_MOVE: int dy = eventY - lastY;//微小的移动量 if (isNeedMove()) { if (normal.isEmpty()) { //记录了childView的临界状态的左、上、右、下 normal.set(childView.getLeft(), childView.getTop(), childView.getRight(), childView.getBottom()); } //重新布局 childView.layout(childView.getLeft(), childView.getTop() + dy / 2, childView.getRight(), childView.getBottom() + dy / 2); } lastY = eventY;//重新赋值 break; case MotionEvent.ACTION_UP: if (isNeedAnimation()) { //使用平移动画 int translateY = childView.getBottom() - normal.bottom; TranslateAnimation translateAnimation = new TranslateAnimation(0, 0, 0, -translateY); translateAnimation.setDuration(200); // translateAnimation.setFillAfter(true);//停留在最终位置上 translateAnimation.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationStart(Animation animation) { isFinishAnimation = false; } @Override public void onAnimationEnd(Animation animation) { isFinishAnimation = true; childView.clearAnimation();//清除动画 //重新布局 childView.layout(normal.left, normal.top, normal.right, normal.bottom); //清除normal的数据 normal.setEmpty(); } @Override public void onAnimationRepeat(Animation animation) { } }); //启动动画 childView.startAnimation(translateAnimation); } break; } return super.onTouchEvent(ev); } //判断是否需要执行平移动画 private boolean isNeedAnimation() { return !normal.isEmpty(); } private boolean isNeedMove() { int childMeasuredHeight = childView.getMeasuredHeight();//获取子视图的高度 int scrollViewMeasuredHeight = this.getMeasuredHeight();//获取布局的高度 Log.e("TAG", "childMeasuredHeight = " + childMeasuredHeight); Log.e("TAG", "scrollViewMeasuredHeight = " + scrollViewMeasuredHeight); int dy = childMeasuredHeight - scrollViewMeasuredHeight;//dy >= 0 int scrollY = this.getScrollY();//获取用户在y轴方向上的偏移量 (上 + 下 -) if (scrollY <= 0 || scrollY >= dy) { return true;//按照我们自定义的MyScrollView的方式处理 } //其他处在临界范围内的,返回false。即表示,仍按照ScrollView的方式处理 return false; } }
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