Related
I would like to smoothly animate some views Y position based on the user scrolling a bottom sheet.
http://imgur.com/dVBlh83
However the animation is slightly jerky.
This is probably because scrolling a bottomsheet gives me a slideOffset at some interval, which is too infrequent to setTranlationY like I'm currently doing.
Is there a better way to do this.
Bottom sheet callback
BottomSheetBehavior.BottomSheetCallback() {
#Override public void onSlide(#NonNull View bottomSheetView, float slideOffset) {
int offset = (int) (slideOffset * 100);
if (offset > 0) {
scrollingHeaderView.animate(offset);
}
}
});
scrollingHeaderView
public void animate(int offset) {
position = -(offset / 2);
arrow.setTranslationY(offset * ANIMATION_RATIO_ARROW);
detailView.setTranslationY(offset * ANIMATION_RATIO);
}
I have tried using ObjectAnimator to create lots of small animations at each step.
ObjectAnimator.ofFloat(arrow, "translationY", arrow.getTranslationY(), position * ANIMATION_RATIO_ARROW).start();
in case it helps anyone else. I got it looking much better.
First i set the ration by pixel * range of values i'd get. So offset will be 0 -> 100. Mutliplied by the dp i want the view to move
private static int ANIMATION_RANGE = 100;
arrowScale = -(getResources().getDimensionPixelOffset(R.dimen.arrow_distance) / ANIMATION_RANGE);
containerScale = -(getResources().getDimensionPixelOffset(R.dimen.detail_distance) / ANIMATION_RANGE);
then as the value changes i set this using translationY
arrow.setTranslationY(position * arrowScale);
detailView.setTranslationY(position * containerScale);
I also needed a reset method, which animate back to the original position
public void reset() {
arrow.animate().setDuration(100).translationY(0);
detailView.animate().setDuration(100).translationY(0);
}
Actually I don't know how it properly called - overlay, parallax or slideUP, whatever, I have an Activity called "cafe details" which presents a Container(LinearLayout) with header information (name, min price, delivery time min e.t.c) and other container (ViewPager) which contains a ExpandableListView with something information (menus&dishes) and all I want to do is slide up my Viewpager when scrolls listview to scpecific Y position to cover(or overlay) header information.
A similar effect (but with parallax that I don't need to use) looks like this
I can detect when user scrolling listview down or up but how I can move container with ViewPager to overlay other container? Please give me ideas, regards.
UPD
I have tried a huge number of ways how to implement it and all of them unfortunately are not suitable. So now I have come to next variant - add scroll listener to ListView, calculate scrollY position of view and then based on that move the viewpager on y axis by calling setTranslationY();
Here is some code
1) ViewPager's fragment
mListView.setOnScrollListener(new AbsListView.OnScrollListener() {
#Override
public void onScrollStateChanged(AbsListView absListView, int i) {
}
#Override
public void onScroll(AbsListView absListView, int i, int i1, int i2) {
if (getActivity() != null) {
((MainActivity) getActivity()).resizePagerContainer(absListView);
}
}
});
2) MainActivity
//object fields
int previousPos;
private float minTranslation;
private float minHeight;
<--------somewhere in onCreate
minTranslation = - (llVendorDescHeaders.getMeasuredHeight()+llVendorDescNote.getMeasuredHeight());
//llVendorDescHeaders is linearLayout with headers that should be hidden
//lVendorDescNote is a textView on green background;
minHeight = llVendorDescriptionPagerContainer.getMeasuredHeight();
//llVendorDescriptionPagerContainer is a container which contains ViewPager
--------->
public void resizePagerContainer(AbsListView absListView){
final int scrollY = getScrollY(absListView);
if (scrollY != previousPos) {
final float translationY = Math.max(-scrollY, minTranslation);
llVendorDescriptionPagerContainer.setTranslationY(translationY);
previousPos = scrollY;
}
}
private int getScrollY(AbsListView view) {
View child = view.getChildAt(0);
if (child == null) {
return 0;
}
int firstVisiblePosition = view.getFirstVisiblePosition();
int top = child.getTop();
return -top + firstVisiblePosition * child.getHeight() ;
}
This simple solution unfortunately has a problem - it is blinking and twitching (I don't know how to call it right) when scrolls slowly. So instead setTranslationY() I've used an objectAnimator:
public void resizePagerContainer(AbsListView absListView){
.............
ObjectAnimator moveAnim = ObjectAnimator.ofFloat(llVendorDescriptionPagerContainer, "translationY", translationY);
moveAnim.start();
..............
}
I don't like this solution because 1) anyway it does resize viewpager with delay, not instantly 2) I don't think that is good idea to create many ObjectAnimator's objects every time when I scroll my listView.
Need your help and fresh ideas. Regards.
I'm assuming that you are scrolling the top header (the ImageView is a child of the header) based on the scrollY of the ListView/ScrollView, as shown below:
float translationY = Math.max(-scrollY, mMinHeaderTranslation);
mHeader.setTranslationY(translationY);
mTopImage.setTranslationY(-translationY / 3); // For parallax effect
If you want to stick the header/image to a certain dimension and continue the scrolling without moving it anymore, then you can change the value of mMinHeaderTranslation to achieve that effect.
//change this value to increase the dimension of header stuck on the top
int tabHeight = getResources().getDimensionPixelSize(R.dimen.tab_height);
mHeaderHeight = getResources().getDimensionPixelSize(R.dimen.header_height);
mMinHeaderTranslation = -mHeaderHeight + tabHeight;
The code snippets above are in reference to my demo but I think it's still general enough for you.
If you're interested you can check out my demo
https://github.com/boxme/ParallaxHeaderViewPager
Have you tried CoordinatorLayout from this new android's design support library? It looks like it's what you need. Check this video from 3:40 or this blog post.
Sorry for the confusing title, I cannot express the problem very concisely...
I have an Android app with a ListView that uses a circular / "infinite" adapter, which basically means I can scroll it up or down as much as I want and the items will wrap around when it reaches the top or bottom, making it seem to the user as if he is spinning an infinitely long list of (~100) repeating items.
The point of this setup is to let the user select a random item, simply by spinning / flinging the listview and waiting to see where it stops. I decreased the friction of the Listview so it flings a bit faster and longer and this seems to work really nice. Finally I placed a partially transparent image on top of the ListView to block out the top and bottom items (with a transition from transparent to black), making it seem as if the user is "selecting" the item in the middle, as if they were on a rotating "wheel" that they control by flinging.
There is one obvious problem: after flinging the ListView does not stop at a particular item, but it can stop hovering between two items (where the first visible item is then only partially shown). I want to avoid this because in that case it is not obvious which item has been "randomly selected".
Long story short: after the ListView has finished scrolling after flinging, I want it to stop on a "whole" row, instead of on a partially visible row.
Right now I implemented this behavior by checking when the scrolling has stopped, and then selecting the first visible item, as such:
lv = this.getListView();
lv.setFriction(0.005f);
lv.setOnScrollListener(new OnScrollListener() {
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {}
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (scrollState == OnScrollListener.SCROLL_STATE_IDLE)
{
if (isAutoScrolling) return;
isAutoScrolling = true;
int pos = lv.getFirstVisiblePosition();
lv.setSelection(pos);
isAutoScrolling = false;
}
}
});
This works reasonably well, apart from one glaringly obvious problem... The first visible item might only be visible for a pixel or two. In that case, I want the ListView to jump "up" for those two pixels so that the second visible item is selected. Instead, of course, the first visible item is selected which means the ListView jumps "down" almost an entire row (minus those two pixels).
In short, instead of jumping to the first visible item, I want it to jump to the item that is visible the most. If the first visible item is less than half visible, I want it to jump to the second visible item.
Here's an illustration that hopefully conveys my point. The left most ListView (of each pair) shows the state after flinging has stopped (where it comes to a halt), and the right ListView shows how it looks after it made the "jump" by selecting the first visible item. On the left I show the current (wrong) situation: Item B is only barely visible, but it is still the first visible item so the listView jumps to select that item - which is not logical because it has to scroll almost an entire item height to get there. It would be much more logical to scroll to Item C (which is depicted on the right) because that is "closer".
(source: nickthissen.nl)
How can I achieve this behavior? The only way I can think of is to somehow measure how much of the first visible item is visible. If that is more than 50%, then I jump to that position. If it is less than 50%, I jump to that position + 1. However I have no clue how to measure that...
Any idea's?
You can get the visible dimensions of a child using the getChildVisibleRect method. When you have that, and you get the total height of the child, you can scroll to the appropriate child.
In the example below I check whether at least half of the child is visible:
View child = lv.getChildAt (0); // first visible child
Rect r = new Rect (0, 0, child.getWidth(), child.getHeight()); // set this initially, as required by the docs
double height = child.getHeight () * 1.0;
lv.getChildVisibleRect (child, r, null);
if (Math.abs (r.height ()) < height / 2.0) {
// show next child
}
else {
// show this child
}
Here's my final code inspired by Shade's answer.
I forgot to add "if(Math.abs(r.height())!=height)" at first. Then it just scrolls twice after it scroll to correct position because it's always greater than height/2 of childView.
Hope it helps.
listView.setOnScrollListener(new AbsListView.OnScrollListener(){
#Override
public void onScrollStateChanged(AbsListView view,int scrollState) {
if (scrollState == SCROLL_STATE_IDLE){
View child = listView.getChildAt (0); // first visible child
Rect r = new Rect (0, 0, child.getWidth(), child.getHeight()); // set this initially, as required by the docs
double height = child.getHeight () * 1.0;
listView.getChildVisibleRect (child, r, null);
if(Math.abs(r.height())!=height){//only smooth scroll when not scroll to correct position
if (Math.abs (r.height ()) < height / 2.0) {
listView.smoothScrollToPosition(listView.getLastVisiblePosition());
}
else if(Math.abs (r.height ()) > height / 2.0){
listView.smoothScrollToPosition(listView.getFirstVisiblePosition());
}
else{
listView.smoothScrollToPosition(listView.getFirstVisiblePosition());
}
}
}
}
#Override
public void onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) {
}});
Follow these 3 steps, then you can get exactly what you want!!!!
1.Initialize the two variable for scrolling up and down:
int scrollingUp=0,scrollingDown=0;
2.Then increment the value of the variable based on scrolling:
#Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if(mLastFirstVisibleItem<firstVisibleItem)
{
scrollingDown=1;
}
if(mLastFirstVisibleItem>firstVisibleItem)
{
scrollingUp=1;
}
mLastFirstVisibleItem=firstVisibleItem;
}
3.Then do the changes in the onScrollStateChanged():
#Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
switch (scrollState) {
case SCROLL_STATE_IDLE:
if(scrollingUp==1)
{
mainListView.post(new Runnable() {
public void run() {
View child = mainListView.getChildAt (0); // first visible child
Rect r = new Rect (0, 0, child.getWidth(), child.getHeight()); // set this initially, as required by the docs
double height = child.getHeight () * 1.0;
mainListView.getChildVisibleRect (child, r, null);
int dpDistance=Math.abs (r.height());
double minusDistance=dpDistance-height;
if (Math.abs (r.height()) < height/2)
{
mainListView.smoothScrollBy(dpDistance, 1500);
}
else
{
mainListView.smoothScrollBy((int)minusDistance, 1500);
}
scrollingUp=0;
}
});
}
if(scrollingDown==1)
{
mainListView.post(new Runnable() {
public void run() {
View child = mainListView.getChildAt (0); // first visible child
Rect r = new Rect (0, 0, child.getWidth(), child.getHeight()); // set this initially, as required by the docs
double height = child.getHeight () * 1.0;
mainListView.getChildVisibleRect (child, r, null);
int dpDistance=Math.abs (r.height());
double minusDistance=dpDistance-height;
if (Math.abs (r.height()) < height/2)
{
mainListView.smoothScrollBy(dpDistance, 1500);
}
else
{
mainListView.smoothScrollBy((int)minusDistance, 1500);
}
scrollingDown=0;
}
});
}
break;
case SCROLL_STATE_TOUCH_SCROLL:
break;
}
}
You probably solved this problem but I think that this solution should work
if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
View firstChild = lv.getChildAt(0);
int pos = lv.getFirstVisiblePosition();
//if first visible item is higher than the half of its height
if (-firstChild.getTop() > firstChild.getHeight()/2) {
pos++;
}
lv.setSelection(pos);
}
getTop() for first item view always return nonpositive value so I don't use Math.abs(firstChild.getTop()) but just -firstChild.getTop(). Even if this value will be >0 then this condition is still working.
If you want to make this smoother then you can try to use lv.smoothScrollToPosition(pos) and enclose all above piece of code in
if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
post(new Runnable() {
#Override
public void run() {
//put above code here
//and change lv.setSelection(pos) to lv.smoothScrollToPosition(pos)
}
});
}
Once you know the first visible position, you should be able to use View.getLocationinWindow() or View.getLocationOnScreen() on the next position's view to get the visible height of the first. Compare that to the View's height, and scroll to the next position if appropriate.
You may need to tweak it to account for padding, depending on what your rows look like.
I haven't tried the above, but it seems like it should work. If it doesn't, here's another, probably less robust idea:
getLastVisiblePosition(). If you take the difference between last and first, you can see how many positions are visible on the screen. Compare that to how many positions were visible when the list was first populated(scroll position 0).
If the same number of positions are visible, simply scroll to the first visible position as you are doing. If there is one more visible, scroll to "first + 1" position.
If you can get the position of the row that needs to be scrolled to, you can use the method:
smoothScrollToPosition
So something like:
int pos = lv.getFirstVisiblePosition();
lv.smoothScrollToPosition(pos);
Edit
Try this, sorry I don't have time to test, I'm out and about.
ImageView iv = //Code to find the image view
Rect rect = new Rect(iv.getLeft(), iv.getTop(), iv.getRight(), iv.getBottom());
lv.requestChildRectangleOnScreen(lv, rect, false);
My Solution:
#Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
{
if (swipeLayout.isRefreshing()) {
swipeLayout.setRefreshing(false);
} else {
int pos = firstVisibleItem;
if (pos == 0 && lv_post_list.getAdapter().getCount()>0) {
int topOfNext = lv_post_list.getChildAt(pos + 1).getTop();
int heightOfFirst = lv_post_list.getChildAt(pos).getHeight();
if (topOfNext > heightOfFirst) {
swipeLayout.setEnabled(true);
} else {
swipeLayout.setEnabled(false);
}
}
else
swipeLayout.setEnabled(false);
}
}
Goal
Build a Circular ViewPager.
The first element lets you peak to the last element and swipe to it, and vice versa. You should be able to swipe in either direction forever.
Now this has been accomplished before, but these questions do not work for my implementation. Here are a few for reference:
how to create circular viewpager?
ViewPager as a circular queue / wrapping
https://github.com/antonyt/InfiniteViewPager
How I Tried to Solve the Problem
We will use an array of size 7 as an example. The elements are as follows:
[0][1][2][3][4][5][6]
When you are at element 0, ViewPagers do not let you swipe left! How terrible :(. To get around this, I added 1 element to the front and end.
[0][1][2][3][4][5][6] // Original
[0][1][2][3][4][5][6][7][8] // New mapping
When the ViewPageAdapter asks for (instantiateItem()) element 0, we return element 7. When the ViewPageAdapter asks for element 8 we return element 1.
Likewise in the OnPageChangeListener in the ViewPager, when the onPageSelected is called with 0, we setCurrentItem(7), and when it's called with 8 we setCurrentItem(1).
This works.
The Problem
When you swipe to the left from 1 to 0, and we setCurrentItem(7), it will animate all the way to right by 6 full screens. This doesn't give the appearance of a circular ViewPager, it gives the appearence rushing to the last element in the opposite direction the user requested with their swipe motion!
This is very very jarring.
How I Tried to Solve This
My first inclination was to turn off smooth (ie, all) animations. It's a bit better, but it's now choppy when you move from the last element to the first and vice versa.
I then made my own Scroller.
http://developer.android.com/reference/android/widget/Scroller.html
What I found was that there is always 1 call to startScroll() when moving between elements, except when I move from 1 to 7 and 7 to 1.
The first call is the correct animation in direction and amount.
The second call is the animation that moves everything to the right by multiple pages.
This is where things got really tricky.
I thought the solution was to just skip the second animation. So I did. What happens is a smooth animation from 1 to 7 with 0 hiccups. Perfect! However, if you swipe, or even tap the screen, you are suddenly (with no animation) at element 6! If you had swiped from 7 to 1, you'll actually be at element 2. There is no call to setCurrentItem(2) or even a call to the OnPageChangeListener indicating that you arrived at 2 at any point in time.
But you're not actually at element 2, which is kind of good. You are still at element 1, but the view for element 2 will be shown. And then when you swipe to the left, you go to element 1. Even though you were really at element 1 already.. How about some code to help clear things up:
Animation is broken, but no weird side effects
#Override
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
super.startScroll(startX, startY, dx, dy, duration);
}
Animation works! But everything is strange and scary...
#Override
public void startScroll(int startX, int startY, int dx, int dy, int duration) {
if (dx > 480 || dx < -480) {
} else {
super.startScroll(startX, startY, dx, dy, duration);
}
}
The ONLY difference is that when the second animation (bigger than the width of the 480 pixel screen) is called, we ignore it.
After reading through the Android Source code for Scroller, I found that startScroll does not start scrolling anything. It sets up all the data to be scrolled, but doesn't initiate anything.
My Hunch
When you do the circular action (1 to 7 or 7 to 1), there are two calls to startScroll(). I think something in between the two calls is causing an issue.
User scrolls from element 1 to element 7 causing a jump from 0 to 7. This should animate to the left.
startScroll() is called indicating a short animation to the left.
STUFF HAPPENS THAT MAKES ME CRY PROBABLY I THINK
startScroll() is called indicating a long animation to the right.
Long animation to the right occurs.
If I comment out 4, then 5 becomes "Short correct animation to the left, things go crazy"
Summary
My implementation of a Circular ViewPager works, but the animation is broken. Upon trying to fix the animation, it breaks the functionality of the ViewPager. I am currently spinning my wheels trying to figure out how to make it work. Help me! :)
If anything is unclear please comment below and I will clarify. I realize I was not very precise with how things are broken. It's difficult to describe because it's not even clear what I'm seeing on the screen. If my explanation is an issue I can work on it, let me know!
Cheers,
Coltin
Code
This code is slightly modified to make it more readable on its own, though the functionality is identical to my current iteration of the code.
OnPageChangeListener.onPageSelected
#Override
public void onPageSelected(int _position) {
boolean animate = true;
if (_position < 1) {
// Swiping left past the first element, go to element (9 - 2)=7
setCurrentItem(getAdapter().getCount() - 2, animate);
} else if (_position >= getAdapter().getCount() - 1) {
// Swiping right past the last element
setCurrentItem(1, animate);
}
}
CircularScroller.startScroll
#Override
public void startScroll(int _startX, int _startY, int _dx, int _dy, int _duration) {
// 480 is the width of the screen
if (dx > 480 || dx < -480) {
// Doing nothing in this block shows the correct animation,
// but it causes the issues mentioned above
// Uncomment to do the big scroll!
// super.startScroll(_startX, _startY, _dx, _dy, _duration);
// lastDX was to attempt to reset the scroll to be the previous
// correct scroll distance; it had no effect
// super.startScroll(_startX, _startY, lastDx, _dy, _duration);
} else {
lastDx = _dx;
super.startScroll(_startX, _startY, _dx, _dy, _duration);
}
}
CircularViewPageAdapter.CircularViewPageAdapter
private static final int m_Length = 7; // For our example only
private static Context m_Context;
private boolean[] created = null; // Not the best practice..
public CircularViewPageAdapter(Context _context) {
m_Context = _context;
created = new boolean[m_Length];
for (int i = 0; i < m_Length; i++) {
// So that we do not create things multiple times
// I thought this was causing my issues, but it was not
created[i] = false;
}
}
CircularViewPageAdapter.getCount
#Override
public int getCount() {
return m_Length + 2;
}
CircularViewPageAdapter.instantiateItem
#Override
public Object instantiateItem(View _collection, int _position) {
int virtualPosition = getVirtualPosition(_position);
if (created[virtualPosition - 1]) {
return null;
}
TextView tv = new TextView(m_Context);
// The first view is element 1 with label 0! :)
tv.setText("Bonjour, merci! " + (virtualPosition - 1));
tv.setTextColor(Color.WHITE);
tv.setTextSize(30);
((ViewPager) _collection).addView(tv, 0);
return tv;
}
CircularViewPageAdapter.destroyItem
#Override
public void destroyItem(ViewGroup container, int position, Object view) {
ViewPager viewPager = (ViewPager) container;
// If the virtual distance is distance 2 away, it should be destroyed.
// If it's not intuitive why this is the case, please comment below
// and I will clarify
int virtualDistance = getVirtualDistance(viewPager.getCurrentItem(), getVirtualPosition(position));
if ((virtualDistance == 2) || ((m_Length - virtualDistance) == 2)) {
((ViewPager) container).removeView((View) view);
created[getVirtualPosition(position) - 1] = false;
}
}
I think the best doable approach would be instead of using a normal list to have a wrapper to the List that when the get(pos) method is executed to obtain the object to create the view, you make something like this get(pos % numberOfViews) and when it ask for the size of the List you put that the List is Integer.MAX_VALUE and you start your List in the middle of it so you can say that is mostly impossible to have an error, unless they actually swipe to the same side until the reach the end of the List. I will try to post a proof of concept later this weak if the time allows me to do so.
EDIT:
I have tried this piece of code, i know is a simple textbox shown on each view, but the fact is that it works perfectly, it might be slower depending on the total amount of views but the proof of concept is here. What i have done is that the MAX_NUMBER_VIEWS represents what is the maximum numbers of times a user can completely give before he is stopped. and as you can see i started the viewpager at the length of my array so that would be the second time it appears so you have one turn extra to the left and right but you can change it as you need it. I hope i do not get more negative points for a solution that in fact does work.
ACTIVITY:
pager = (ViewPager)findViewById(R.id.viewpager);
String[] articles = {"ARTICLE 1","ARTICLE 2","ARTICLE 3","ARTICLE 4"};
pager.setAdapter(new ViewPagerAdapter(this, articles));
pager.setCurrentItem(articles.length);
ADAPTER:
public class ViewPagerAdapter extends PagerAdapter {
private Context ctx;
private String[] articles;
private final int MAX_NUMBER_VIEWS = 3;
public ViewPagerAdapter(Context ctx, String[] articles) {
this.ctx = ctx;
this.articles = articles.clone();
}
#Override
public int getCount() {
return articles.length * this.MAX_NUMBER_VIEWS;
}
#Override
public Object instantiateItem(ViewGroup container, int position) {
TextView view = new TextView(ctx);
view.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT));
int realPosition = position % articles.length;
view.setText(this.articles[realPosition]);
((ViewPager) container).addView(view);
return view;
}
#Override
public void destroyItem(ViewGroup container, int position, Object object) {
((ViewPager) container).removeView((View) object);
}
#Override
public boolean isViewFromObject(View view, Object object) {
return view == ((View) object);
}
#Override
public Parcelable saveState() {
return null;
}
}
I have a situation in that I am using a horizontal scroll view with images and using buttons to smooth scroll to the different image locations. Now it works okay I was just wondering if anyone knew of anyway to slow down the smooth scroll method, i.e. having a longer annimation time? As currently the snapping happens pretty quickly.
Perhaps through an override of the smoothscroll, I have tried to search for this/examples but to no luck.
So any ideas?
Thanks,
Si
How About:
ObjectAnimator animator=ObjectAnimator.ofInt(yourHorizontalScrollView, "scrollX",targetXScroll );
animator.setDuration(800);
animator.start();
THis is one way, which works well for me:
new CountDownTimer(2000, 20) {
public void onTick(long millisUntilFinished) {
hv.scrollTo((int) (2000 - millisUntilFinished), 0);
}
public void onFinish() {
}
}.start();
So here the horizontal scroll view (hv) moves in two seconds from position 0 to 2000 or to the end of the view if smaller than 2000px. Easy to adjust...
Subclass HorizontalScrollView, use reflection to get access to the private field mScroller in HorizontalScrollView. Of course, this will break if the underlying class changes the field name, it defaults back to original scroll implemenation.
The call myScroller.startScroll(scrollX, getScrollY(), dx, 0, 500); changes the scroll speed.
private OverScroller myScroller;
private void init()
{
try
{
Class parent = this.getClass();
do
{
parent = parent.getSuperclass();
} while (!parent.getName().equals("android.widget.HorizontalScrollView"));
Log.i("Scroller", "class: " + parent.getName());
Field field = parent.getDeclaredField("mScroller");
field.setAccessible(true);
myScroller = (OverScroller) field.get(this);
} catch (NoSuchFieldException e)
{
e.printStackTrace();
} catch (IllegalArgumentException e)
{
e.printStackTrace();
} catch (IllegalAccessException e)
{
e.printStackTrace();
}
}
public void customSmoothScrollBy(int dx, int dy)
{
if (myScroller == null)
{
smoothScrollBy(dx, dy);
return;
}
if (getChildCount() == 0)
return;
final int width = getWidth() - getPaddingRight() - getPaddingLeft();
final int right = getChildAt(0).getWidth();
final int maxX = Math.max(0, right - width);
final int scrollX = getScrollX();
dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX;
myScroller.startScroll(scrollX, getScrollY(), dx, 0, 500);
invalidate();
}
public void customSmoothScrollTo(int x, int y)
{
customSmoothScrollBy(x - getScrollX(), y - getScrollY());
}
Its a scroller the scroll automatically and continously. It was made to show a credits screen by continously scrolling through a list of images. This might help you or give you some idea.
https://github.com/blessenm/SlideshowDemo
Use .smoothScrollToPositionFromTop instead. Example
listView.smoothScrollToPositionFromTop(scroll.pos(),0,scroll.delay());
wherescroll is a simple variable from a class that takes current screen position .get() returns new position .pos() and time of smooth scrolling .delay ... etc
Or even easier, .smoothScrollTo(). Example:
hsv.smoothScrollTo(x, y);
Docs: Android Developer ScrollView docs
Have a look at http://developer.android.com/reference/android/widget/Scroller.html:
The duration of the scroll can be passed in the constructor and specifies the maximum time that the scrolling animation should take