Android 如何设置 ScrollView 的起始位置？
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How to set the starting position of a ScrollView?
提问by RyanCW
I have been trying to set the initial position of a scroll View but have not found a way. Does anyone have any ideas? Also I have a GoogleMaps fragment as a children of the scroll View.
我一直在尝试设置滚动视图的初始位置，但没有找到方法。有没有人有任何想法？此外，我有一个 GoogleMaps 片段作为滚动视图的子项。
Thanks,
谢谢，
Ryan
瑞安
回答by Philipp Jahoda
Yes, that is possible:
是的，这是可能的：
ScrollView.scrollTo(int x, int y);
ScrollView.smoothScrollTo(int x, int y);
ScrollView.smoothScrollBy(int x, int y);
can be used for that. The x and y parameters are the coordinates to scroll to on the horizontal and vertical axis.
可以用于那个。x 和 y 参数是要在水平和垂直轴上滚动到的坐标。
Example in code:
代码示例：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.your_layout);
ScrollView sv = (ScrollView) findViewById(R.id.scrollView);
sv.scrollTo(0, 100);
}
In that example, once the Activityis started, your ScrollViewwill be scrolled down 100 pixels.
在该示例中，一旦Activity启动，您ScrollView将向下滚动 100 像素。
You can also try to delaythe scrolling process:
您还可以尝试延迟滚动过程：
final ScrollView sv = (ScrollView) findViewById(R.id.scrollView);
Handler h = new Handler();
h.postDelayed(new Runnable() {
@Override
public void run() {
sv.scrollTo(0, 100);
}
}, 250); // 250 ms delay
回答by Vijay
The accepted answer is not working for me. There is no direct way to set the initial position of a scroll view.
接受的答案对我不起作用。没有直接的方法来设置滚动视图的初始位置。
However, you can set the initial position before drawing the scroll view, like this:
但是，您可以在绘制滚动视图之前设置初始位置，如下所示：
rootView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
scrollView.getViewTreeObserver().removeOnPreDrawListener(this);
scrollView.setScrollY(100);
return false;
}
});
You can also use scrollView.setScrollY(100)inside Handler, but that will be jerky while scrolling.
您也可以使用scrollView.setScrollY(100)inside Handler，但滚动时会生涩。
回答by Amir194
After several hours internet searching
经过几个小时的互联网搜索
this worked for me :
这对我有用：
ScrollView.post(new Runnable() {
@Override
public void run() {
//setting position here :
ScrollView.scrollTo(X, Y);
}
});
回答by Selti99
The problem is that the ScrollView doesn't know its size before it been laid out. A solution is to save the scroll position unil onLayouthas been called and then set the scroll position.
问题是 ScrollView 在布局之前不知道它的大小。一个解决方案是保存滚动位置直到onLayout被调用，然后设置滚动位置。
Here is an example (kotlin):
这是一个示例（kotlin）：
class MyScrollView constructor(context: Context, attrs: AttributeSet) : ScrollView(context, attrs) {
private var hasStartPositionBeenSet = false
var startPosition = 0
override fun onLayout(changed: Boolean, l: Int, t: Int, r: Int, b: Int) {
super.onLayout(changed, l, t, r, b)
if(!hasStartPositionBeenSet) {
scrollTo(0, startPosition)
hasStartPositionBeenSet = true
}
}
}
class MyActivity: Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
/* ... */
findViewById<MyScrollView>(R.id.scrollView).startPosition = scrollPosition
}
}
回答by Selti99
Scrollview sw = (ScrollView) findViewById(R.id.scrollView);
sw.post(new Runnable() {
public void run() {
sw.smoothScrollTo(0, 5000);
}
});
回答by Josef K.
None of the answers worked for me. My ScrollViewis part of a surrounding LinearLayout. I put the adjustment of the ScrollViewinto the onDraw()method of this LinearLayoutlike this:
没有一个答案对我有用。MyScrollView是周围LinearLayout. 我把这个的调整ScrollView放到这个onDraw()方法里LinearLayout是这样的：
@Override
protected void onDraw(Canvas canvas){
if(scrollAdjustTries > 2){
return;
}
scrollAdjustTries++;
mScrollView.scrollTo(0, mModel.scrollLine());
}
Very ugly, but working.
非常丑陋，但工作。
