I have a ViewPager Fragment with 3 fragments. Each of it has an image as background and a TextView. The TextView is always absolute on the left side of the screen (not the Fragment itself). When I move the fragments with my finger, it stays at the correct position. Also when I move it fast. But when I let it slide into the other Fragment, the TextView doesn't stays at the correct position. It looks like it lags around.
It should stay like in these 2 pictures:
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
SingleTabFragment singleTabFragment = (SingleTabFragment) mSectionsPagerAdapter.getRegisteredFragment(position);
TextView textView = singleTabFragment.getNonResizingTextView();
ViewGroup.MarginLayoutParams marginLayoutParams = (ViewGroup.MarginLayoutParams)textView.getLayoutParams();
marginLayoutParams.leftMargin = positionOffsetPixels;
textView.setLayoutParams(marginLayoutParams);
}
I really don't know what the problem is. I tried it multiple ways, i added Thread.sleep(50); to see if it also happens there. And yes, also there it doesn't work correct. How can I fix this?
EDIT:
Now I have put in the middle. But the problem is the same.
Here is how it should look like (I know, not that much frames. But I think you will get the point):
And if I let it slide it looks like this:
TextView textView = singleTabFragment.getNonResizingTextView();
textView.translationX = positionOffsetPixels;
You should not do marginLayoutParams.leftMargin = positionOffsetPixels; because changing the margin may change the position of the View, which will cause the View to be re-layout on every frame. That is why it is lagging.
Changing the translationX will only change how the view is drawn instead of it's position.
You can use following method to do the same instead of doing it in onPageScrolled:
mPager.setPageTransformer(false, new FadePageTransformer());
public class FadePageTransformer implements ViewPager.PageTransformer {
public void transformPage(View view, float position) {
view.setAlpha(1 - Math.abs(position));
if (position < 0) {
view.setScrollX(-(int) ((float) (view.getWidth()) * -position));
} else if (position > 0) {
view.setScrollX((int) ((float) (view.getWidth()) * position));
} else {
view.setScrollX(0);
}
}
}
use textView.setTranslationX(positionOffsetPixels); instead of margins
Have a look at Slowing speed of Viewpager controller in android
You can set custom duration for Viewpager scrolling.
Related
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.
As I've a master in MS Paint, I will just upload a picture selfdescripting what I'm trying to achieve.
I've searched, but I'm not really sure what do I've to search. I've found something called Animations. I managed to rotate, fade, etc an element from a View (with this great tutorial http://www.vogella.com/articles/AndroidAnimation/article.html)
But this is a bit limited for what I'm trying to achieve, and now, I'm stuck, because I don't know how is this really called in android development. Tried words like "scrollup layouts" but I didn't get any better results.
Can you give me some tips?
Thank you.
You can see a live example, with this app: https://play.google.com/store/apps/details?id=alexcrusher.just6weeks
Sincerely,
Sergi
Use something like this as your layout (Use Linear, Relative or other layout if you wish):
<LinearLayout
android:id="#+id/lty_parent">
<LinearLayout
android:id="#+id/lyt_first" />
<LinearLayout
android:id="#+id/lyt_second"/>
</LinearLayout>
And then in an onClick method on whatever you want to use to control it, set the Visibility between Visible and Gone.
public void buttonClickListener(){
((Button) findViewById(R.id.your_button))
.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if (lyt_second.getVisibility() == View.GONE) {
lyt_second.setVisibility(View.VISIBILE);
}
else {
lyt_second.setVisibility(View.GONE);
}
});
Which is fine if you just want a simple appear/disappear with nothing fancy. Things get a little bit more complicated if you want to animate it, as you need to play around with negative margins in order to make it appear to grow and shrink, like so:
We use the same onClick method that we did before, but this time when we click it starts up a custom SlideAnimation for the hidden/visible view.
#Override
public void onClick(View v) {
SlideAnimation slideAnim = new SlideAnimation(lyt_second, time);
lyt_second.startAnimation(slideAnim);
}
The implementation of the SlideAnimation is based on a general Animation class, which we extend and then Override the transformation.
public SlideAnimation(View view, int duration) {
//Set the duration of the animation to the int we passed in
setDuration(duration);
//Set the view to be animated to the view we passed in
viewToBeAnimated = view;
//Get the Margin Parameters for the view so we can edit them
viewMarginParams = (MarginLayoutParams) view.getLayoutParams();
//If the view is VISIBLE, hide it after. If it's GONE, show it before we start.
hideAfter = (view.getVisibility() == View.VISIBLE);
//First off, start the margin at the bottom margin we've already set.
//You need your layout to have a negative margin for this to work correctly.
marginStart = viewMarginParams.bottomMargin;
//Decide if we're expanding or collapsing
if (marginStart == 0){
marginEnd = 0 - view.getHeight();
}
else {
marginEnd = 0;
}
//Make sure the view is visible for our animation
view.setVisibility(View.VISIBLE);
}
#Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
super.applyTransformation(interpolatedTime, t);
if (interpolatedTime < 1.0f) {
// Setting the new bottom margin to the start of the margin
// plus the inbetween bits
viewMarginParams.bottomMargin = marginStart
+ (int) ((marginEnd - marginStart) * interpolatedTime);
// Request the layout as it happens so we can see it redrawing
viewToBeAnimated.requestLayout();
// Make sure we have finished before we mess about with the rest of it
} else if (!alreadyFinished) {
viewMarginParams.bottomMargin = marginEnd;
viewToBeAnimated.requestLayout();
if (hideAfter) {
viewToBeAnimated.setVisibility(View.GONE);
}
alreadyFinished = true;
}
hideAfter = false;
}
}
EDIT: If anyone had used this code before and found that if you click on the button that starts the animation more than once before the animation was finished, it would mess up the animation from then on, causing it to always hide the view after the animation finished. I missed the reset of the hideAfter boolean near the bottom of the code, added it now.
you can do this manually by using setvisibility feature on the event onClick()
or
use this
dynamically adding two views one below other
I want to move a view when the ViewPager scrolls. I found scroll listener in view pager, with the parameter positionOffset, which I use to adjust the left margin of the view I want to move.
It works, but the scrolling isn't smooth anymore. If I comment the scroll listener out, it's smooth again. The view I'm animating is super simple - only a small square with a plain color. The requestLayout() call is done only on this view. The code:
pager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
}
#Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
if (positionOffset != 0 || (positionOffset == 0 && position == 0)) {
pars.leftMargin = (int)(scrollablePart * positionOffset);
tabBG.requestLayout();
}
}
#Override
public void onPageScrollStateChanged(int state) {
}
});
I don't know what's the problem, I have other place with a view which I animate in a similar way (adjusting margins, according to a -not pager-slider) and it's smooth. I also have seen an app where the positions of some views are adjusted dynamically according to the scrolling of a pager, and it's very smooth.
Any idea? Thanks in advance!
Any animation that involves requestLayout() will be slow. If all you are trying to do is move a View around, use a TranslateAnimation, or View.offsetLeftAndRight() or View.setTranslationX(), etc. Do not use requestLayout() or anything layout related.
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 am trying to achieve this in a ViewPager
The first fragment (blue) is displayed and the beginning of the next fragment must be displayed as well, so the user understands he can swipe to switch views.
The idea is scroll 20% of the screen programmatically to the left.
Any thoughts are welcome
EDIT: This is exactly what I need to to: the central view needs to overlap both side views
You can try adding this to your PageAdapter:
public float getPageWidth(int position) {
if (position == 0 || position == 2) {
return 0.8f;
}
return 1f;
}
Try using a negative value for ViewPager.setPageMargin.
This function worked better than the answer marked as correct (for me anyway).
#Override
public float getPageWidth(int position) {
return 0.9f;
}
Just place it in your custom PagerAdapter class.
viewpager.setClipToPadding(false);
viewpager.setPageMargin(-50);
#Override
public float getPageWidth(int position) {
return 0.9f;
}
Use this, this will work perfectly and make sure that your class extended to PagerAdapter