Scrolling in viewflipper - android

This is one of the intermediate screens in the app.
I'm using a viewflipper.
I'm setting this view using vf.setDisplayedChild(9); where vf is ViewFlipper object.
Referring to above screen-shot, if I reach upto country field (which I'm checking through isFocused()), the whole view should scroll by some pixels (equal to keyboard height).
If I hadn't used viewflipper, then I would have tried something like scrollTo(x, y).
But how do I scroll in viewflipper.
Any help appreciated.

You could place a ScrollView as the view inside of the ViewFlipper.
The only problem I think you may still run into is that the keyboard should automatically shift things up (in my experience it doesn't function properly while in fullscreen though). I'd try displaying that screen without the fullscreen enabled and you may find that your behavior is handled automatically.

Related

Android - keeping a single element contained on screen

I'm experimenting to see if the layout scheme I want to use is possible. I want to have an XML layout that's scrollable. Within that scrollable layout, I want to have a single line going horizontally across the screen (I used just a View with a fixed height and different color). When that horizontal line reaches the top of the screen, and as I scroll down through the layout, I want it to stop and remain at the top of the screen while being able to scroll through everything below it.
I've been messing around in XML trying to get it to work, basically putting a bunch of junk before it and after it.
Any ideas as to how that might work? Would I have to do something fancy with the java code to fix the red line at the top when the scroll position reaches a certain point? Your help would be greatly appreciated.
I am assuming you want something like Gmail app where when you scroll a mail the header sticks on top... To do this, you need 2 views. You have your regular scroller below and overlay a fixed view on top (you can use a relative layout to do this). When your cell goes past a certain spot, you want to populate and set the visibility of the fixed view to VISIBLE. This would give the impression that the view you want to 'stick' to the top really just got stuck rather than scrolled out of view. You'll have to work out the opposite scrolling scenario too based on the location and height of the scrolled cell/view.
HTH

Android - How to determinate ViewFlipper children size when not displayed?

I'm actually making an application using a ViewFlipper to display 3 differents custom views. These views are, for each one, in a ScrollView (putting the ViewFlipper in a single ScrollView isn't making my onFling gestures really efficient). And i'm actually trying to synchronize the three Scrollbars position. At this point using a single ScrollView would have been easier but i trying to not use this solution.
I'm using a ScrollListener for each ScrollView to set the others ScrollView scroll position like in this thread : Synchronise ScrollView scroll positions - android.
The problem is that this method will works but the first time. When i'm on a ScrollView, the two others are not drawn already and their height is null. So setting their scroll position isn't working.
/*Instanciate ScollViews*/
scrollViewLeft = (ScrollableScrollView) findViewById(R.id.scroll_prev);
scrollViewCenter =(ScrollableScrollView) findViewById(R.id.scroll_current);
scrollViewRight = (ScrollableScrollView) findViewById(R.id.scroll_next);
/*Fill views with events*/
setDayEvents(calIns.getPrevCal(),leftDayView);
setDayEvents(calIns.getActualCal(),centerDayView);
setDayEvents(calIns.getNextCal(),rightDayView);
scrollViewLeft.setScrollViewListener(this);
scrollViewCenter.setScrollViewListener(this);
scrollViewRight.setScrollViewListener(this);
So finally my question is, should i use another method to find the scroll position of the two others views ? Or can i force the view to be drawn in a ViewFlipper ?
Thanks :)
Clement.
Try saving the positions in global variables before you change the views and then just apply it to your current view.
Thanks Egor for having answered. I think it is a good idea. I already have a Singleton to handle variables. So i add the variable position with getters and setters.
The probleme here is than even if I override the method "onSizeChanged" in my custom ScrollView, this will apply only for the first view shown.
PS: I'm still starting on Android development and I don't really know how to handle with
interactions on views when they aren't ready (for example getting width when they are not drawn yet).
Edit 1 day later :
Ok i found what was the problem, it is because the size of my views inside the scrollviews wasn't defined (the scrollview was drawn before the view inside it). So by setting the scroll inside the "onSizeChanged" method of the views works well.

What does android:isScrollContainer do?

Does anyone know what android:isScrollCOntainer = (boolean) or $(View).setScrollContainer(boolean) do?
At first I thought this would be the answer to set a View inside a ScrollView NOT to scroll with ScrollView, but it doesn't seem to be the case.
On Android Developers it says,
"Set this if the view will serve as a scrolling container, meaning that it can be resized to shrink its overall window so that there will be space for an input method. "
Can anyone kindly explain what this description means?
What is a scrolling container in this case?
What kind of input method is available?
A scrolling container is one where the size of the container is independent of it's content.
For instance you can make a ScrollView or ListView of height 100 pixels, but you can fit as much content in as you want. Similarly regardless of the size of the content in the view, you can set the size the of the View to whatever you'd like.
If a container is scrollable, then Android knows it can shrink the size of the container without rendering parts of the content of the container inaccessible (since the user can just scroll down to see things not on screen). It uses this for when the SoftKeyboard is opened - if a container is scrollable it will shrink it as much as possible in an attempt to keep all of the elements on screen.
So ScrollView, ListView, GridView etc are all examples of scrolling containers.
I am looking in to the same thing and I am not sure exactly what it means either. The input method is however the soft keyboard. Changing it affects how the views resize when an edittext is clicked and the keyboard pops up. Look in to android:windowSoftInputMode for more information.
I hope this was at least a little bit helpful!

Android: Detect when ScrollView has finished scrolling and bouncing back?

I have a ScrollView which has two hidden images, one at the top and one at the bottom. In between there is a bunch of visible content.
What I need to do is make these images hidden by default but when you scroll all the way up or all the way down you could see them as you're scrolling. But then as soon as you stop scrolling it should bounce back to the visible area so that the hidden images aren't showing.
Basically I'm trying to imitate the bounce scrolling feature of the iphone UIScrollView.
I have my ScrollView all setup and I do a scroll at the beginning so as to hide the top hidden image. Now all I need to do is detect when a scrolling has ended, figure out the Y position, and check whether a hidden image is shown. If it is, I would just programmatically scroll the view back so that the hidden image is hidden.
I hope all that made sense.
So anyways, I know how to programmatically scroll a ScrollView. Now what I need is some sort of callback to tell me when a ScrollView ended scrolling and also a way to get the ScrollView's current 'Y' position. Are there any such methods I could use?
I looked through the ScrollView docs but nothing jumped out at me. I'm still not very familiar with the Android naming schemes so maybe I missed something obvious somewhere.
Anyways, any help would be appreciated here. Cheers.
You can use an OnTouchListener to detect when the user presses/releases the list.
You can also use the onScrollStateChanged method of the OnScrollListener class (most likely in conjunction with a touch listener) to detect changes in the SCROLL_STATE - when the list has stopped scrolling the state will change from a state that is not SCROLL_STATE_IDLE to SCROLL_STATE_IDLE.
Alternatively if you are using 2.3 or above you can use an OverScroller to get the desired effect (see Modifying Android OverScroll for how to change the over scroll effect to an iPhone like one).

ViewFlipper caching issue

The views are not cached in a ViewFlipper. Is there a way wherein we can get an image of the view and show it to user so that he sees the Ui as we see on Home scrren(when we swipe the previous view also moves along and when we lift our finger, only then the next view is shown completely.)
What I want to do is that when the user starts moving his finegr on screen, the view should also move along(create an image of view).
I am not getting to do this, as when we swipe the present view goes and next view comes, we do not get both visible when we r moving our finger on screen.
Please if anyone gets what I am trying to do, do help me.
Thanks,
Farha
It's tricky to get scroll and swipe tracking working on Android, while using ViewAnimator or its subclasses.
They allow you to set in and out animations and start them at a given moment, but they work with discrete, either-this-or-the-other-view animations. They are actually using FrameLayout and after in or out animation is executed, other views' visibility is set to View.GONE to hide them from showing up under/over your current View.
The Launcher and the Gallery application are actually doing the functionality you want, by using a different approach.
They track the user touch input (onTouchEvent()), on MotionEvent.ACTION_MOVE they perform animations manually and on MotionEvent.ACTION_UP snap to the appropriate view, just like in the iPhone.
Unfortunately, this approach is actually more complicated than it looks like.
With the manual handling, you have to ensure that you are taking care of everything related to the touch input. This includes a lot of flag-raising, value-checking, event-delegating, etc.
If you want to get better acquainted with this, take a look at these classes from Gallery3D or Launcher's source code.
One other way to get nice horizontal scrolling is to use HorizontalScrollView.
You have to figure out a way to recycle your views, like you would with a ListView and you have to add the snap-to-view logic, but if you have to take care of a small number of views it could be the easiest approach.
Hope that helps.

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