android组件的下拉回弹,Android界面上拉下拉的回弹效果实例代码

废话不多说,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.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,-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;

}

}

以上所述是小编给大家介绍的Android界面上拉下拉的回弹效果实例代码,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对编程小技巧网站的支持!

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