public class MineListView extends ListView implements Runnable {
private float mLastDownY = 0f;
private int mDistance = 0;
private int mStep = 0;
private boolean mPositive = false;
public MineListView (Context context, AttributeSet attrs) {
super(context, attrs);
}
public MineListView (Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public MineListView (Context context) {
super(context);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: //手指按下时触发
if (mLastDownY == 0f && mDistance == 0) {
mLastDownY = event.getY();
return true;
}
break;
case MotionEvent.ACTION_CANCEL:
break;
case MotionEvent.ACTION_UP: //手指抬起之后触发
if (mDistance != 0) {
mStep = 1;
mPositive = (mDistance >= 0);
this.post(this);
return true;
}
mLastDownY = 0f;
mDistance = 0;
break;
case MotionEvent.ACTION_MOVE: //手指按下之后滑动触发
if (mLastDownY != 0f) {
mDistance = (int) (mLastDownY - event.getY());
if ((mDistance < 0 && getFirstVisiblePosition() == 0 &&
getChildAt(0).getTop() == 0) || (mDistance > 0 &&
getLastVisiblePosition() == getCount() - 1)) {
//第一个位置并且是想下拉，就滑动或者最后一个位置向上拉
//这个判断的作用是在非顶端的部分不会有此滚动
mDistance /= 2; //这里是为了减少滚动的距离
scrollTo(0, mDistance); //滚动
return true;
}
}
mDistance = 0;
break;
}
return super.onTouchEvent(event);
}
public void run() {
mDistance += mDistance > 0 ? -mStep : mStep;
scrollTo(0, mDistance);
if ((mPositive && mDistance <= 0) || (!mPositive && mDistance >= 0)) {
scrollTo(0, 0);
mDistance = 0;
mLastDownY = 0f;
return;
}
mStep += 1;
this.postDelayed(this, 7);
}
} |
