Develop Reference

How to approach this fade transition

I am building an app using Android Studio, and I cannot figure out how to approach this issue I am facing.
I have a recyclerview that takes up about two-thirds of the lower half of the screen. Above it are three other elements. I need those elements to disappear when the recyclerview gets scrolled, and I need the recyclerview to scale up to fill the entire screen. I have found ways to do this, but they all cause the items inside of the recyclerview to scale up as well, distorting them.

Use this implementation:-
recyclerview.addOnScrollListener(new HidingScrollListener()
{
#Override
public void onHide()
{
tabss.animate().translationY(tabss.getHeight())
.setInterpolator(new AccelerateInterpolator(2)).start();
filtershow.animate().translationY(-filtershow.getHeight())
.setInterpolator(new AccelerateInterpolator(1));
}
#Override
public void onShow()
{
tabss.animate().translationY(0).setInterpolator(new
DecelerateInterpolator(2)).start();
filtershow.animate().translationY(0).setInterpolator
(new DecelerateInterpolator(1)).start();
}
});

How do I make an infinitely looping RecyclerView while also being able to scroll to an item programmatically?

I want to make a RecyclerView that scrolls infinitely while also being able to scroll to an item programmatically.
At the moment I've made the RecyclerView loop infinitely using this hacky method: https://stackoverflow.com/a/31254146/7443375
i.e. Overriding my adapter
#Override
public int getCount() {
return Integer.MAX_VALUE;
}
Getting position of item in my adapter like so:
int positionInList = position % fragmentList.size();
And then initializing my RecyclerView's scroll position like so:
recyclerView.getLayoutManager().scrollToPosition(Integer.MAX_VALUE / 2);
However, in my Fragment that has the RecyclerView, I want to be able to scroll to a specific item in my list (i.e. item 3 out of a list of 10 items). When I call
recyclerView.getLayoutManager().scrollToPosition(2);
The list goes into an infinite scroll. I can't figure out how to go to the specific item itself.
Furthermore, how can I make sure that the specific item is centered in the screen? I am using LinearSnapHelper to snap the items in the center of the screen as I scroll, but LinearSnapHelper does not seem to work when setting positions programmatically.

Try this way..
recyclerView.post(new Runnable() {
#Override
public void run() {
new CountDownTimer(Integer.MAX_VALUE, 20 ) {
public void onTick(long millis) {
recyclerView.scrollBy(0, 20);
}
public void onFinish() {
}
}.start();
}
});

scrollView.scrollTo() speed control?

I would like to programmatically scroll to a specific point in a
scrollView...which I can do just fine...
Except I land there instantly.
Is there a way to control the speed of the scroll so it looks smoother?
Could somebody point me to an animation with a scrollview?

You can use object animator to scroll:
ObjectAnimator.ofInt(scrollView, "scrollY", scrollTo).setDuration(duration).start();
or you can use ContDownTimer:
new CountDownTimer(2000, 20) {
public void onTick(long millisUntilFinished) {
scrollView.scrollTo((int) (2000 - millisUntilFinished), 0);
}
public void onFinish() {
}
}.start();

There is method for that if you want to scroll it smoothly smoothScrollTo()
use it Like
scrollView.smoothScrollTo(xPos, yPos);

How Scroll android Scrollview automatically and lock it when comes to bottom

I am creating app that needs to scroll slowlly the scrollview automatically to bottom and lock at the bottom. I have tried several ways but it does not functuation correctly? any library or source code?

Android: ScrollView force to bottom
Check this link. May be you get the desired result.
Edit:
new CountDownTimer(2000, 20) {
public void onTick(long millisUntilFinished) {
scrolView.scrollTo((x,y));
}
public void onFinish() {
}
}.start();
or instead of scrollTo() try using scrollBy()

Android: Hiding a view off the top edge of the screen

Would it be possible to hide a view off the top edge of the screen, and only have it appear if the user scrolls upwards?
My first attempt used a scrollview, but it seems that scrollTo() doesn't work unless I used postDelayed (it doesn't even work with Post()). I tried adding it to the scrollview's view tree observer onPreDraw() event and it still doesn't work unless I delay it, so there is an ugly glitch when the activity is first launched.
The second issue is that if the onscreen keyboard is minimized, the view no longer needs to scroll so hiding things by using a scroll offset no longer works. I thought about manipulating the height in code, but this seems pretty hackish.
Is there a better way to do this than by using a scrollview? Alternatively, Does anyone have any tips on the best place to place the scrollTo (the end of onCreate does not work nor the other places I have tried) so I don't need to use postDelayed? That would at least eliminate one glitch.
Thanks!
This is the code I'm using right now, which is the least glitchy but I don't understand why it doesn't work until the third time onPreDraw() is called.
mScrollView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener()
{
#Override
public boolean onPreDraw()
{
final int fieldYStart = mFieldIWantAtTheTop.getTop();
if (mFieldIWantAtTheTopYStart != fieldYStart
|| mScrollView.getScrollY() < 10)
{
mFieldIWantAtTheTopYStart = fieldYStart;
mScrollView.post(new Runnable()
{
#Override
public void run()
{
Log.v("Testing", "scrolling!");
mScrollView.scrollTo(0, mFieldIWantAtTheTopYStart);
Log.v("Testing", "scroll is now=" + mScrollView.getScrollY());
}
});
}
return true;
}
});
I also tried using a custom scrollview as mentioned below, but this does not solve the issue of the graphical glitch:
#Override
public void onMeasure(int measureWidthSpec, int measureHeightSpec) {
super.onMeasure(measureWidthSpec, measureHeightSpec);
Log.v("Testing", "Scrolling");
post(
new Runnable()
{
public void run()
{
scrollTo(0, 100);
Log.v("Testing", "ScrollY = " + getScrollY());
}
});
}
This code works as does the onPreDraw() code above but there is still a glitch when the activity is launched because the activity is first drawn with the scroll at 0.

I haven't tried this, but you may want to create a custom ScrollView and override onMeasure:
ScrollView scroll = new ScrollView(this) {
#Override
public void onMeasure(int measureWidthSpec, int measureHeightSpec) {
super.onMeasure(measureWidthSpec, measureHeightSpec);
scrollTo(...);
}
};
It seems like this would be the earliest point that scrollTo would be valid.
Edit - I found this answer, which apparently worked for the asker. Is this the method you tried?