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技術社區[雲棲]
android listview仿iphone彈簧特效
IOS常見視圖有一個彈性回退的動畫效果，Android 從2.3開始實現了下衝到底部和上衝到底部時顏色漸變動畫效果。View類有兩個很重要的方法scrollTo和scrollBy，允許移動視圖的可見區域。這就是我們今天實現動畫效果的理論基礎，我們可以在android數據列表頂部往下拖動列表或底部拖動相應的移動數據列表，當停止拖動時再讓它彈回去。下麵是代碼部分：
package com.linghu;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ListView;
public class Pull_ListView extends ListView implements Runnable {
private float mLastDownY = 0f;
private int mDistance = 0;
private int mStep = 10;
private boolean mPositive = false;
public Pull_ListView (Context context, AttributeSet attrs) {
super(context, attrs);
}
public Pull_ListView (Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public Pull_ListView (Context context) {
super(context);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (mLastDownY == 0f && mDistance == 0) {
mLastDownY = event.getY();
return true;
}
break;
case MotionEvent.ACTION_CANCEL:
break;
case MotionEvent.ACTION_UP:
if (mDistance != 0) {
mStep = 1;
mPositive = (mDistance >= 0);
this.post(this);
return true;
}
mLastDownY = 0f;
mDistance = 0;
break;
case MotionEvent.ACTION_MOVE:
if (mLastDownY != 0f) {
mDistance = (int) (mLastDownY - event.getY());
if ((mDistance < 0 && getFirstVisiblePosition() == 0 && getChildAt(0).getTop() == 0) || (mDistance > 0 && getLastVisiblePosition() == getCount() - 1)) {
mDistance /= 2;
scrollTo(0, mDistance);
return true;
}
}
mDistance = 0;
break;
}
return super.onTouchEvent(event);
}
@Override
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, 10);
}
} // end class
最後更新：2017-04-02 00:06:52