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.
Related
I would like to know how to go about doing this small problem that I am encountering while making a video player app.
On clicking the first control(the rectangular icon) in the above image the following view must be displayed instead of it which I am quite unsure as to how to do it. Here is what it is replaced by
Also please note, by any chance the activity should not be changed. I have been able to design the views individually but having problem changing them at runtime when user clicks. Could someone go about explaining as to how it can be done or provide some suitable links to achieve my goal. Thanks.
For something as simple as this you can just change the visibility of the views.
view.setVisibility(View.INVISIBLE)
Or the more effective:
view.setVisibility(View.GONE)
Do that on the views you want gone, I suggest a wrapper class. It's either this or changing the contentView as describded below.
this.setContentView(R.layout.newLayoutToUse);
However, I have a feeling there is a better way to do what you want. It's overkill to load a complete new layout if you just want to change the image of some buttons or imageviews.
This might be a stupid solution, 'cause i'm terribly tired right now, but why not use the bringToFront() method on the View that you want to display in the front? Display them both in front of each other, maybe in a RelativeLayout, and then swap between them as you wish.
They are small objects, so don't consume memory. I don't see why this shouldn't work.
OR
Place them above one another, so they overlap and then make the above view visible/invisible depending on which one you need to display.
OR
just remembered I read somewhere that you can scroll through a ScrollView automatically from code. So display both Views in a ScrollView in succession and when pressing the button or whatever, you scroll down to make the next menu visible. When pres back, you scroll up to make the previous thing available. Should work, and might also make a nice animation between changing of the menus.
I cant seem to find the answer to this, mainly because I don't know what it is called.
I am going to expand a few features in my app, currently users can touch and drag to move forward in a list of images. What I want is for the users to "swipe" there finger and then all of these images will move under acceleration and will slowly come to a stop.
Is this a gesture? If so is it the "Fling" gesture?
There are several ways to do so.
Use ListView
Use Gallery
Use ScrollView
Use HorizontalScrollView
Write your custom ViewGroup or View
For the last approach, you have to detect the Fling gesture as you said and handle all the scrolling animations involved.
I am searching for an easy way to implement a view flipping like used in several occasions by google apps.
Behaviour should be like this: OnScroll the view should move to the side and show the content of the next page. If scrolled far enough the view should move smoothly into position (after lifting your finger) and snap into place. If not scrolled far enough and the finger is lifted, the original view should smoothly move to the original view and snap into place.
I search around and didn't figure out a easy way.
So I though about something like this:
Hide the ScrollBars of the horizontal ScrollView.
Set the scrollView position manually according to the position I get from a GestureDetector.
I am pretty sure that this way works. But it seems to complicated to me, because there are to many things that have to be programmed. Like the animation (Smooth acceleration, deceleration, snap), Gesture, calculation of the actual position....
So my Question: Am I on the right way or is there an easier approach? Did I miss something during I searched for a solution? Is this function already implemented by android or does it really have to be done by myself?
Look for this tutorial. Also if you try to search here, on SO, you will find thousands of similar question with lots of different solutions. You can choose one, that will useful for you.
I have a text view where in i have to keep ages between 1-99. I also have two buttons ^ and v(i mean up and down arrows) on clicking them the values of the age should smoothly scroll to next or previous value.
I have been trying different ways but couldnt achieve smooth scrolling. Can anyone please give me any idea of how to achieve the task.
I think the easiest way is to simply put the TextView within a ScrollView, and let the arrows interact with the ScrollView, by using things like the fling method and playing around with the velocity parameter to suit your needs.
Use the animation framework.
When pressing down, start the 'down'-animation.
When pressing up, start the 'up'-animation.
Read more about animation here: http://developerlife.com/tutorials/?p=343
View animation is not much matured and hence i am noy sure if that can be used for moving the views.
Please find the description below:
Another disadvantage of the view
animation system is that it only
modified where the View was drawn, and
not the actual View itself. For
instance, if you animated a button to
move across the screen, the button
draws correctly, but the actual
location where you can click the
button does not change, so you have to
implement your own logic to handle
this.
Source
To scroll smoothly you can try using the scroller component.
Reference
What you would need to do is pass the duration of the scroll in the constructor and then use the property
setFinalY(int newY)
to increment the counter position by 1 unit (equal to the height of the item).
Please let me know if that helps!
I want to give my app a nice touch by allowing users to slide the page left or right instead of just using next/previous buttons (similar to the home screen).
What is the best way to do that? I assume I would have to override one of the Activity.on... methods and that I would also have to put my page's main View in a ViewGroup that allows me to shift pages left and right.
ViewFlipper is your friend!
Here you can see a nice video of the ViewFlipper in action and also a very good tutorial:
http://www.inter-fuser.com/2009/07/android-transistions-slide-in-and-slide.html
The solution is even easier these days with the release of Compatibility Package r3. You can download here: http://developer.android.com/sdk/compatibility-library.html
It includes
ViewPager: A ViewGroup that manages the layout for the child views, which the user can swipe between.
PagerAdapter: An adapter that populates the ViewPager with the views that represent each page.
and Fragment versions of those, if you are that way inclined.
The pager code is compatible back to API version 4 (1.6), and I just implemented a dynamically generated viewPager coming off a dynamically generated ListView in about 2 hours. I'm a novice, so this is definitely the preferred path.
There is an example app here: http://geekyouup.blogspot.com/2011/07/viewpager-example-from-paug.html
If one wants to flip between two activities perhaps one can apply this animated transition:
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
startActivity(intent);
finish();
//transition using XML view animations
overridePendingTransition(R.anim.slideinfromright, R.anim.slideouttoleft);
Use GestureDetector to detect if the touch event is a scroll.
If the first event to the first call to onScroll is ACTION_DOWN then you should see if it was a dominantly horizontal scroll. If so then your scroll is started and you should shift the absolute position of the view that fills the page.
For non deprecated absolute positioning, see my answer here Android: Alternative to AbsoluteLayout (I really do need absolute positioning)
You will want to be cautions of whether you return true to consume the touch events or not.
GestureDetector does not have a callback for scrolling having stopped. You will have to check if there was an ACTION_UP before you call GestureDetector.onTouchEvent and if there was an action up and you did have an unfinished scroll then you should set the absolute position to the destination location and use a TranslateAnimation to make it look nice moving from current to destination.
Edit:
GestureDetector did not work well at all if the child views also wanted to respond to touch events. I ended up creating a subclass of FrameLayout (one of the most basic layouts and the closest thing to a non intrusive parent view) and overriding dispatchTouchEvent. I just took all the events and did the detection myself.
cant we use Gallery view here?? with the adapter the whole page can be inflated inside gallery view adapter getView() and it will manage the left right scrolling perfectly.