我正在做自动水平滚动.所以我有15件物品.现在我想访问12项,所以我的索引是11.但我无法在索引发生时自动滚动它.
horizontalScrollView.scrollTo(12,0);
@Override
public void onPageSelected(int page) {
for(int i = 0; i < holeTitle.length; i++) {
if(i == page) {
title[i].setTextColor(0xffffffff);
horizontalScrollView.scrollTo(12,0);
}
else {
title[i].setTextColor(0xffe0e0e0);
}
}
}
请专家看看.
解决方法
DmRomantsov的答案是滚动到第12个按钮的正确方法.但是,getLeft()和getRight()方法返回0,因为屏幕上尚未显示布局.现在计算布局父级和子级的宽度还为时过早.要实现它,您需要在
onWindowFocusChanged内进行自动滚动.
@Override
public void onWindowFocusChanged(boolean hasFocus){
super.onWindowFocusChanged(hasFocus);
if(hasFocus){
// do smoothScrollTo(...);
}
}
但是,在Fragment中,上面的方法不起作用.我只是写它来提供线索,了解这个概念.要在Fragment中具有相同的行为,您只需要执行一个Runnable,它可以显示您的UI时间.然后,使用面向水平的LinearLayout执行此操作：
// Init variables
HorizontalScrollView mHS;
LinearLayout mLL;
// onCreateView method
@Override
public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.layout_container,container,false);
// Find your views
mHS = (HorizontalScrollView)view.findViewById(R.id.hscrollview);
mLL = (LinearLayout)view.findViewById(R.id.hscrollview_container);
// Do a Runnable on the inflated view
view.post(new Runnable() {
@Override
public void run() {
Log.v("","Left position of 12th child = "+mLL.getChildAt(11).getLeft());
mHS.smoothScrollTo(mLL.getChildAt(11).getLeft(),0);
}
});
return view;
}
Middle HorizontalScrollView：
你的问题是自动滚动到你的第12个孩子.但是,在下面的评论中,您要求我在HorizontalScrollView的中间自动滚动,我假设在每个设备上.您需要计算屏幕的宽度,容器的总宽度以及设备宽度内显示的子项数.这是一个简单的代码：
// Auto scroll to the middle (regardless of the width screen)
view.post(new Runnable() {
@Override
public void run() {
// Width of the screen
DisplayMetrics metrics = getActivity().getResources()
.getDisplayMetrics();
int widthScreen = metrics.widthPixels;
Log.v("","Width screen total = " + widthScreen);
// Width of the container (LinearLayout)
int widthContainer = mLL.getWidth();
Log.v("","Width container total = " + widthContainer );
// Width of one child (Button)
int widthChild = mLL.getChildAt(0).getWidth();
Log.v("","Width child = " + widthChild);
// Nb children in screen
int nbChildInScreen = widthScreen / widthChild;
Log.v("","Width screen total / Width child = " + nbChildInScreen);
// Width total of the space outside the screen / 2 (= left position)
int positionLeftWidth = (widthContainer
- (widthChild * nbChildInScreen))/2;
Log.v("","Position left to the middle = " + positionLeftWidth);
// Auto scroll to the middle
mHS.smoothScrollTo(positionLeftWidth,0);
}
});
/**
* Your value might be resumed by:
*
* int positionLeftWidth =
* ( mLL.getWidth() - ( mLL.getChildAt(0).getWidth() *
* ( metrics.widthPixels / mLL.getChildAt(0).getWidth() ) ) ) / 2;
*
**/
具有所选值的Middle HorizontalScrollView：
我有点误解了真正的要求.实际上,您想要自动滚动直到选定的子视图,并在屏幕中间显示此视图.
然后,我更改了最后一个int positionLeftWidth,它现在引用所选视图相对于其父项的左侧位置,一个屏幕中包含的子项数以及所选视图的半宽.所以,除了positionLeftWidth之外,代码与上面相同：
// For example the chosen value is 7
// 7th Child position left
int positionChildAt = mLL.getChildAt(6).getLeft();
// Width total of the auto-scroll (positionLeftWidth)
int positionLeftWidth = positionChildAt - // position 7th child from left less
( ( nbChildInScreen // ( how many child contained in screen
* widthChild ) / 2 ) // multiplied by their width ) divide by 2
+ ( widthChild / 2 ); // plus ( the child view divide by 2 )
// Auto-scroll to the 7th child
mHS.smoothScrollTo(positionLeftWidth,0);
然后,无论getChildAt()方法中的值如何,无论宽度屏幕如何,您始终都会在屏幕中间选择(在您的情况下)按钮.
