// 允许从外部传递视差效果的控件进来
public void setParallaxImageView(ImageView parallaxImageView) {
this.parallaxImageView = parallaxImageView;
Drawable drawable = parallaxImageView.getDrawable();
maxHeight = drawable.getIntrinsicHeight();// 获取图片的最大高度
originH = parallaxImageView.getHeight();// 获取图片的起始高度
System.out.println("ParallaxListView.setParallaxImageView,originH="+originH);
}
获取资源高度
@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_UP:
// 将图片从当前高度弹回最初的高度
final int currentH = parallaxImageView.getHeight();
// 动态生成一个值的变化
ValueAnimator animator = ValueAnimator.ofFloat(1);
animator.addUpdateListener(new AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator value) {
System.out.println("ParallaxListView.onAnimationUpdate,time="+value.getCurrentPlayTime()+";Fraction="+value.getAnimatedFraction()+";value="+value.getAnimatedValue());
int newHeight = evaluate(value.getAnimatedFraction(), currentH, originH);
parallaxImageView.getLayoutParams().height = newHeight;
parallaxImageView.requestLayout();
}
});
animator.setDuration(200);
animator.setInterpolator(new OvershootInterpolator(4));
animator.start();
break;
default:
break;
}
return super.onTouchEvent(ev);// 一定要使用super来返回，因为列表的滚动要由ListView处理
}
处理事件，当起来的时候，不断刷新图片的高度，
animator.setInterpolator(new OvershootInterpolator(4));
这个是可以设置回弹的次数
@Override
// 当列表被滑动到两端尽头的时候被调用
// deltaY 两次滑动间的变化大小
protected boolean overScrollBy(int deltaX, int deltaY, int scrollX,
int scrollY, int scrollRangeX, int scrollRangeY,
int maxOverScrollX, int maxOverScrollY, boolean isTouchEvent) {
System.out.println("deltaY="+deltaY+";scrollY="+scrollY+";scrollRangeY="+scrollRangeY+";maxOverScrollY="+maxOverScrollY+";isTouchEvent="+isTouchEvent);
if (deltaY < 0 && isTouchEvent) {
int newHeight = parallaxImageView.getHeight() + Math.abs(deltaY / 2);
if (newHeight < maxHeight) {
parallaxImageView.getLayoutParams().height = newHeight;
parallaxImageView.requestLayout();
}
}
return super.overScrollBy(deltaX, deltaY, scrollX, scrollY, scrollRangeX,
scrollRangeY, maxOverScrollX, maxOverScrollY, isTouchEvent);
}
当超过一定值的时候调用