我有一个很长的带有滚动视图的活动。它是一个包含用户必须填写的各种字段的表单。我在表单的中间有一个复选框,当用户选中它时,我想滚动到视图的特定部分。是否有办法以编程方式滚动到EditText对象(或任何其他视图对象)?
此外,我知道这是可能的使用X和Y坐标,但我想避免这样做,因为形式可能会从用户到用户的变化。
我有一个很长的带有滚动视图的活动。它是一个包含用户必须填写的各种字段的表单。我在表单的中间有一个复选框,当用户选中它时,我想滚动到视图的特定部分。是否有办法以编程方式滚动到EditText对象(或任何其他视图对象)?
此外,我知道这是可能的使用X和Y坐标,但我想避免这样做,因为形式可能会从用户到用户的变化。
当前回答
我的解决方案是:
int[] spinnerLocation = {0,0};
spinner.getLocationOnScreen(spinnerLocation);
int[] scrollLocation = {0, 0};
scrollView.getLocationInWindow(scrollLocation);
int y = scrollView.getScrollY();
scrollView.smoothScrollTo(0, y + spinnerLocation[1] - scrollLocation[1]);
其他回答
以下是我正在使用的:
int amountToScroll = viewToShow.getBottom() - scrollView.getHeight() + ((LinearLayout.LayoutParams) viewToShow.getLayoutParams()).bottomMargin;
// Check to see if scrolling is necessary to show the view
if (amountToScroll > 0){
scrollView.smoothScrollTo(0, amountToScroll);
}
这将获得显示视图底部所需的滚动量,包括视图底部的任何边距。
我基于WarrenFaith的答案做了一个小工具方法,这段代码也考虑了视图是否已经在滚动视图中可见,不需要滚动。
public static void scrollToView(final ScrollView scrollView, final View view) {
// View needs a focus
view.requestFocus();
// Determine if scroll needs to happen
final Rect scrollBounds = new Rect();
scrollView.getHitRect(scrollBounds);
if (!view.getLocalVisibleRect(scrollBounds)) {
new Handler().post(new Runnable() {
@Override
public void run() {
scrollView.smoothScrollTo(0, view.getBottom());
}
});
}
}
我的解决方案是:
int[] spinnerLocation = {0,0};
spinner.getLocationOnScreen(spinnerLocation);
int[] scrollLocation = {0, 0};
scrollView.getLocationInWindow(scrollLocation);
int y = scrollView.getScrollY();
scrollView.smoothScrollTo(0, y + spinnerLocation[1] - scrollLocation[1]);
检查Android源代码,你会发现ScrollView已经有一个成员函数scrollToChild(View),它做的正是所请求的。不幸的是,这个函数由于某种模糊的原因被标记为private。在这个函数的基础上,我写了下面的函数,它可以找到指定为参数的视图上方的第一个ScrollView,并滚动它,使它在ScrollView中可见:
private void make_visible(View view)
{
int vt = view.getTop();
int vb = view.getBottom();
View v = view;
for(;;)
{
ViewParent vp = v.getParent();
if(vp == null || !(vp instanceof ViewGroup))
break;
ViewGroup parent = (ViewGroup)vp;
if(parent instanceof ScrollView)
{
ScrollView sv = (ScrollView)parent;
// Code based on ScrollView.computeScrollDeltaToGetChildRectOnScreen(Rect rect) (Android v5.1.1):
int height = sv.getHeight();
int screenTop = sv.getScrollY();
int screenBottom = screenTop + height;
int fadingEdge = sv.getVerticalFadingEdgeLength();
// leave room for top fading edge as long as rect isn't at very top
if(vt > 0)
screenTop += fadingEdge;
// leave room for bottom fading edge as long as rect isn't at very bottom
if(vb < sv.getChildAt(0).getHeight())
screenBottom -= fadingEdge;
int scrollYDelta = 0;
if(vb > screenBottom && vt > screenTop)
{
// need to move down to get it in view: move down just enough so
// that the entire rectangle is in view (or at least the first
// screen size chunk).
if(vb-vt > height) // just enough to get screen size chunk on
scrollYDelta += (vt - screenTop);
else // get entire rect at bottom of screen
scrollYDelta += (vb - screenBottom);
// make sure we aren't scrolling beyond the end of our content
int bottom = sv.getChildAt(0).getBottom();
int distanceToBottom = bottom - screenBottom;
scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
}
else if(vt < screenTop && vb < screenBottom)
{
// need to move up to get it in view: move up just enough so that
// entire rectangle is in view (or at least the first screen
// size chunk of it).
if(vb-vt > height) // screen size chunk
scrollYDelta -= (screenBottom - vb);
else // entire rect at top
scrollYDelta -= (screenTop - vt);
// make sure we aren't scrolling any further than the top our content
scrollYDelta = Math.max(scrollYDelta, -sv.getScrollY());
}
sv.smoothScrollBy(0, scrollYDelta);
break;
}
// Transform coordinates to parent:
int dy = parent.getTop()-parent.getScrollY();
vt += dy;
vb += dy;
v = parent;
}
}
这对我来说很管用:
targetView.getParent().requestChildFocus(targetView,targetView);
RequestChildFocus(查看子视图,查看焦点)
child -这个ViewParent的想要聚焦的子对象。该视图将包含聚焦视图。它并不一定是真正有焦点的观点。
focused -实际上具有焦点的child的后代视图