版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/qq_40543575/article/details/81023098
近期,项目又一个需求,就是类似于QQ个人中心的下拉回弹的效果.
后来才知道是scrollview实现的功能.分享一下
/**
* Author:AND
* Time: 2018/7/8.
* Email:[email protected]
* Description:能够伸缩头部position为1的View并且带有回弹效果
* Detail:
*/
public class BounceZoomScrollView extends ScrollView {
private static final String TAG = "BounceScrollView";
//----头部收缩属性--------
// 记录首次按下位置
private float mFirstPosition = 0;
// 头部图片是否正在放大
private Boolean mScaling = false;
private View dropZoomView;//需要被放大的view
private int dropZoomViewWidth;
private int dropZoomViewHeight;
//----头部收缩属性end--------
//------尾部收缩属性--------
private View inner;// 子View
private float y;// 点击时y坐标
private Rect normal = new Rect();// 矩形(这里只是个形式，只是用于判断是否需要动画.)
private boolean isCount = false;// 是否开始计算
//最后的坐标
private float lastX = 0;
private float lastY = 0;
//当前坐标
private float currentX = 0;
private float currentY = 0;
//移动的坐标量
private float distanceX = 0;
private float distanceY = 0;
private boolean upDownSlide = false; //判断上下滑动的flag
//------尾部收缩属性end--------
public BounceZoomScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
//初始化
private void init() {
setOverScrollMode(OVER_SCROLL_NEVER);
if (getChildAt(0) != null) {
inner = getChildAt(0);//这个是底部收缩的view
//头部收缩的
ViewGroup vg = (ViewGroup) getChildAt(0);
if (vg.getChildAt(0) != null) {
dropZoomView = vg.getChildAt(0);
}
}
}
/***
* 生成视图工作完成.该函数在生成视图的最后调用，在所有子视图添加完之后. 即使子类覆盖了 onFinishInflate
* 方法，也应该调用父类的方法，使该方法得以执行.
*/
@Override
protected void onFinishInflate() {
//初始化
init();
super.onFinishInflate();
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
//这里只是计算尾部坐标
currentX = ev.getX();
currentY = ev.getY();
switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
distanceX = currentX - lastX;
distanceY = currentY - lastY;
if (Math.abs(distanceX) < Math.abs(distanceY) && Math.abs(distanceY) > 12) {
upDownSlide = true;
}
break;
}
lastX = currentX;
lastY = currentY;
if (upDownSlide && inner != null) commOnTouchEvent(ev);
return super.dispatchTouchEvent(ev);
}
/***
* 触摸事件
*
* @param ev
*/
public void commOnTouchEvent(MotionEvent ev) {
//头部缩放计算
if (dropZoomViewWidth <= 0 || dropZoomViewHeight <= 0) {
dropZoomViewWidth = dropZoomView.getMeasuredWidth();
dropZoomViewHeight = dropZoomView.getMeasuredHeight();
}
switch (ev.getAction()) {
case MotionEvent.ACTION_UP:
//手指离开后头部恢复图片
mScaling = false;
replyImage();
// 手指松开尾部恢复
if (isNeedAnimation()) {
animation();
isCount = false;
}
clear0();
break;
//这里头尾分开处理，互不干扰
case MotionEvent.ACTION_MOVE:
//尾部处理
final float preY = y;// 按下时的y坐标
float nowY = ev.getY();// 时时y坐标
int deltaY = (int) (preY - nowY);// 滑动距离
if (!isCount) {
deltaY = 0; // 在这里要归0.
}
y = nowY;
// 当滚动到最上或者最下时就不会再滚动，这时移动布局
if (isNeedMove()) {
// 初始化头部矩形
if (normal.isEmpty()) {
// 保存正常的布局位置
normal.set(inner.getLeft(), inner.getTop(),
inner.getRight(), inner.getBottom());
}
// 移动布局
inner.layout(inner.getLeft(), inner.getTop() - deltaY / 2,
inner.getRight(), inner.getBottom() - deltaY / 2);
}
isCount = true;
//尾部处理end
//头部处理
if (!mScaling) {
if (getScrollY() == 0) {
mFirstPosition = ev.getY();// 滚动到顶部时记录位置，否则正常返回
} else {
break;
}
}
int distance = (int) ((ev.getY() - mFirstPosition) * 0.6); // 滚动距离乘以一个系数
if (distance < 0) { // 当前位置比记录位置要小，正常返回
break;
}
// 处理放大
mScaling = true;
setZoom(1 + distance);
//头部处理end
break;
}
}
/***
* 回缩动画,尾部往下缩动画
*/
public void animation() {
// 开启移动动画
TranslateAnimation ta = new TranslateAnimation(0, 0, inner.getTop(),
normal.top);
ta.setDuration(600);
inner.startAnimation(ta);
// 设置回到正常的布局位置
inner.layout(normal.left, normal.top, normal.right, normal.bottom);
normal.setEmpty();
}
// 是否需要开启动画
public boolean isNeedAnimation() {
return !normal.isEmpty();
}
// 回弹动画，header往上缩动画 (使用了属性动画)
public void replyImage() {
final float distance = dropZoomView.getMeasuredWidth() - dropZoomViewWidth;
// 设置动画
ValueAnimator anim = ObjectAnimator.ofFloat(0.0F, 1.0F).setDuration((long) (distance * 0.7));
anim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
float cVal = (Float) animation.getAnimatedValue();
setZoom(distance - ((distance) * cVal));
}
});
anim.setDuration(600);
anim.start();
}
//头部缩放
public void setZoom(float s) {
if (dropZoomViewHeight <= 0 || dropZoomViewWidth <= 0) {
return;
}
ViewGroup.LayoutParams lp = dropZoomView.getLayoutParams();
lp.width = (int) (dropZoomViewWidth + s);
lp.height = (int) (dropZoomViewHeight * ((dropZoomViewWidth + s) / dropZoomViewWidth));
dropZoomView.setLayoutParams(lp);
}
/***
* 是否需要移动布局 inner.getMeasuredHeight():获取的是控件的总高度
*
* getHeight()：获取的是屏幕的高度
*
* @return
*/
public boolean isNeedMove() {
int offset = inner.getMeasuredHeight() - getHeight();
int scrollY = getScrollY();
// 0是顶部，后面那个是底部
if (scrollY == 0 || scrollY == offset) {
return true;
}
return false;
}
//清理尾部属性值
private void clear0() {
lastX = 0;
lastY = 0;
distanceX = 0;
distanceY = 0;
upDownSlide = false;
}
}以下代码片段是scrollview上下拉回弹的效果
/**
* Author:AND
* Time: 2018/7/6.
* Email:[email protected]
* Description:
* Detail:
*/
public class SpringBackScrollView extends ScrollView {
private float mDownY;
private float mFirstY;
// 子View
private View childView;
// 初始的位置
private Rect normal = new Rect();
private Handler mHandler = new Handler();
private int speed = 30;
private boolean isPull;
public SpringBackScrollView(Context context) {
super(context);
init();
}
private void init() {
// 禁用下拉到两端发荧光的效果
setOverScrollMode(OVER_SCROLL_NEVER);
}
public SpringBackScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
/**
* 设置回弹的速度。值越大,速度越快。默认为30。
*/
public void setSpringBackSpeed(int speed) {
if (speed <= 0) {
throw new RuntimeException("speed 不能小于或者等于0");
}
this.speed = speed;
}
@Override
protected void onFinishInflate() {
super.onFinishInflate();
if (getChildCount() > 0) {
childView = getChildAt(0);
}
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (childView != null) {
handleScrollTouchEvent(ev);
}
return super.onTouchEvent(ev);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (childView == null) {
return;
}
// ScrollView中的唯一子控件的位置信息, 这个位置信息在整个控件的生命周期中保持不变
normal.set(childView.getLeft(), childView.getTop(), childView.getRight(), childView.getBottom());
}
public void handleScrollTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
mDownY = ev.getY();
mFirstY = ev.getY();
break;
case MotionEvent.ACTION_UP:
springBackLocation();
break;
case MotionEvent.ACTION_MOVE:
// 移除滑动的消息队列
mHandler.removeCallbacksAndMessages(null);
final float preY = mDownY;
final float nowY = ev.getY();
isPull = nowY - mFirstY > 0;
int deltaY = (int) ((preY - nowY) / 2.5);
mDownY = nowY;
// 当滚动到最上或者最下时就不会再滚动，这时移动布局
if (isNeedMove()) {
// 保存正常的布局位置
if (normal.isEmpty()) {
normal.set(childView.getLeft(), childView.getTop(), childView.getRight(), childView.getBottom());
return;
}
// 移动布局
childView.layout(childView.getLeft(), childView.getTop() - deltaY,
childView.getRight(), childView.getBottom() - deltaY);
}
break;
default:
break;
}
}
/**
* 回弹到原始位置
*/
public void springBackLocation() {
final int nowTop = childView.getTop();
final int nowBottom = childView.getBottom();
final int originTop = normal.top;
final int originBottom = normal.bottom;
// 下拉回弹
if (isPull) {
int moveTop = nowTop;
int moveBottom = nowBottom;
int duration = 0;
while (moveTop >= originTop) {
moveTop -= speed;
moveBottom -= speed;
duration += 10;
final int offTop = moveTop;
final int offBottom = moveBottom;
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
if (offTop <= originTop || offBottom <= originBottom) {
childView.layout(normal.left, normal.top, normal.right, normal.bottom);
} else {
childView.layout(normal.left, offTop, normal.right, offBottom);
}
}
}, duration);
}
}
// 上拉回弹
else {
int moveTop = nowTop;
int moveBottom = nowBottom;
int duration = 0;
while (moveTop <= originTop) {
moveTop += speed;
moveBottom += speed;
duration += 10;
final int offTop = moveTop;
final int offBottom = moveBottom;
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
if (offTop >= originTop || offBottom >= originBottom) {
childView.layout(normal.left, normal.top, normal.right, normal.bottom);
} else {
childView.layout(normal.left, offTop, normal.right, offBottom);
}
}
}, duration);
}
}
}
/**
* 是否需要移动布局
*/
public boolean isNeedMove() {
// 注意：慎重选择
// 子View的margin和自己的padding对移动有影响,所以子View最好不要设置marginTop和marginBottom。
// 如果设置了，对判断滑动到底部有些不准确，需要加上下面注释掉margin值，但是不同的机器，测试出有点不一样。
// 获取到子View的margin值
// LayoutParams params = (LayoutParams) childView.getLayoutParams();
// int topMargin = params.topMargin;
// int bottomMargin = params.bottomMargin;
// int offset = childView.getHeight() - getHeight() + getPaddingBottom() + getPaddingTop() + topMargin + bottomMargin;
int offset = childView.getHeight() - getHeight() + getPaddingBottom() + getPaddingTop();
int scrollY = getScrollY();
if (scrollY == 0) {
return true;
} else if (scrollY == offset) {
return true;
}
return false;
}
}