在android4.1及之后版本如何恢复ListView/GridView下拉空白回弹的效果

在android4.1及之后版本如何恢复ListView/GridView下拉空白回弹的效果

[DESCRIPTION]

在Android 4.0及以前的版本，MTK有在Google默认模糊边缘的基础上，做了一个下拉回弹的效果：在ListView和GridView等列表控件的界面上，当滑动画面到顶部或底部时，屏幕上方或下方处会有一个很长的空的区域，松手以后列表会自动弹回。但是android4.1及之后版本无此效果，因为这个效果会引起CTS
test fail!

如果不需要通过CTS测试，请问如何恢复ListView/GridView下拉空白回弹的效果？

效果图：



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2016-5-12 16:21 上传

[SOLUTION]

1.请修改alps/frameworks/base/core/JAVA/android/view/ViewConfiguration.java

修改如下两个变量：

/**

* Max distance to overscroll for edge effects

*/

private static final int OVERSCROLL_DISTANCE = 240; //将0改为240

/**

* Max distance to overfling for edge effects

*/

private static final int OVERFLING_DISTANCE = 240; //将6改为240

2.请修改alps/frameworks/base/core/java/android/widget/AbsListView.java，找到

FlingRunnable这个类的run()方法，找到其中的

private class FlingRunnable implements Runnable {

...

@Override

public void run() {

...

case TOUCH_MODE_OVERFLING: {

final OverScroller scroller = mScroller;

if (scroller.computeScrollOffset()) {

final int scrollY = mScrollY;

final int currY = scroller.getCurrY();

final int deltaY = currY - scrollY; /// 刪掉這行

/// 新增下面的代碼

/**

* M: If user flings on the list in an opposite direction during an over fling quickly,

* the scrollY will change from positive(negative) to negative(positive), so list

* run into abnormal state, view will be not displayed(only mScrollY changes).

*

* To fix this, we only let the list scroll by mScrollY distance to make the list

* restore the normal touch state, then fling the list using the current velocity. @{

*/

final int deltaY;

final boolean needChangeMode = ((mScrollY >= 0 && currY <= 0) || (mScrollY <= 0 &&

currY >= 0));

if (needChangeMode) {

deltaY = -mScrollY;

} else {

deltaY = currY - scrollY;

}

/** @} */

if (overScrollBy(0, deltaY, 0, scrollY, 0, 0,

0, mOverflingDistance, false))

......

......

} else {

Xlog.d(TAG, "FlingRunnable overfling intend to endfling: mScrollY = "+

mScrollY);

if(mScrollY !=0){ //mtk add

if(sDbgMotion) Log.d(TAG,"FlingRunnable TOUCH_MODE_OVERFLING,mScroller

animation fininshed,mScrollY !=0,will startSpringBack");

startSpringback(); //mtk add

}else{ //mtk add

endFling();

} //mtk add

}

break;

标注//mtk add的代码为新增代码

再次提醒，这个改动会导致CTS 测试AbsListViewTest.java中testSetOnScrollListener()这个test

case 测试失败，如果要过CTS，那务必不要做此FAQ的修改