how to change images on a gridview? - android

I'm using a Gridview to display a set of images. What I want to do is that when the user taps on one image, it displays an effect that shows the user that some information is being trasmitted wirelessly and when the phone receives such information the image returns to its original state. Something similar to an animated gif.
This is the code I have until now for the onclick event:
gridview.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
new Thread(new sendingThread()).start();
}
});
At the moment I have a blue shadow over the image as the only onclick event effect, which i'd like to get rid of and substitute for the one I've mentioned.

AniamtionDrawable, you can either embed it into a single item of a gridview and set it to View.VISIBLE then View.GONE or inflate and add it on top of it.
Not sure which one will be the least expensive one.
To preempt the further question. Start the animation upon a view gaining the focus.
I'd also keep track of which buttons are already tapped/selected via SparseBooleanArray within the adapter. You don't want to spawn too many threads, do you?

Related

Android - OnItemClickListener listview

Here's what I want to do:
I have this list of tasks. When I click on one of the items I want this to appear:
Assuming that menubar can be found with
findViewById(R.id.menubar);
Can someone please tell what code I have to put onItemClickListener
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
NOTE: The menubar visibility its set as GONE.
Thanks!
Without looking at the code, a precise answer is not possible. However, when I first wanted to implement a "Quick Action Bar" similar to the one you have shown, I had followed this example here:
http://code.google.com/p/simple-quickactions/
And this with some styling put in: https://github.com/lorensiuswlt/NewQuickAction3D
Hope this helps....
It is a bit difficult without seeing any code, but I can give you some logic ideas.
Based on your description, I'm assuming that those quick bar controls are hidden on EACH listview item so, it goes:
Fotos (visible)
Action Controls (hidden)
[End of Item]
PROJECTOS (visible)
Action Controls (hidden)
...
I think the OnItemClick method gives you the view (item: Fotos, Projectos, etc) that was clicked as the 2nd argument. If you cast that back to whatever layout you used to create the listview items, you should be able to use findViewByID to get access to the hidden controls that are on each listview and make them visible.
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
//Assuming each item is a linear layout
LinearLayout itemAsLL = (LinearLayout)view;
//find the action bar controls
LinearLayout actionControlsLayout = itemAsLL.findViewById(R.name.of.actioncontrols.id);
//Make it visible
actionControlsLayout.setVisibility(VIEW.Visible);
}
You would need to find a way to hide those controls when another item is clicked? Maybe save the view (or position in the adapterView ) as a class variable and when another item is clicked, go to that view/find that view and hide the controls.
I finally found out the answer. Apparently, when you fill a view with lots of tasks, the adapter does not fill everything when you load the layout, so everytime you scroll down, hes putting more items on the listview.
What you have to do is make sure you put a field "loaded" and, in case is false, it does not show the menubar below that item, otherwise, when you click in one of the items of that list, when you scroll down, since they will have the same relative position (if you click on the first item, the position = 0, when you scroll down, there will be another position = 0) the menubar will appear on both items.
Hope it helps ;)

How to animate item in ListView when being clicked?

I want to have one ListView that when I click on the item the view slide out to the left.
So I have:
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
arg1.startAnimation(openAnimation);
}
});
However, animation applied to the different item in the list instead of the one being clicked on. The behavior seems to be random as sometime it happened to more than one item at the same time.
As I suspected this is because of the way Adapter reuse it's view to create item. I went to modify the getView method in my Adapter to inflate new view every time it's being called. Then the animation doesn't happen any more.
Is there a way to resolve this? I tried to move the animation to inside my Adapter but then I can not associate it with other action on the Listview.
Ultimately, I want the item to be clickable but when swipe left/right reveal delete button (iOS delete behavior). Am I on the wrong track here? This should be possible though as Android can implement swipe to remove in the Notification bar.
I recommend that you check this thread also.
I don't think, that this is possible without having to modify your adapter to suit this type of behavior. For what I understand, you don't have any problems with implementing the code recognizing the swipe gestures on different ListView-rows, only with the animation the should follow this gesture on according row(s).
I'd rewrite the adapter to suit at least 2 row types: normal rows, and rows to be deleted. In the "getView()" method of your adapter, you should only reuse the convertView of normal Views. Rows that are to be deleted should not reuse them, so that animating one would not modify the others.
Upon clicking a normal row, you should first tell the adapter that the row on the clicked position is now of type to-be-deleted, call .notifyDatasetChanged(), and then start the animation on that row.

Listview changes image on number of lines when i'm trying to update one line

I have a list of items, which i'd like to "check" with filled star when user clicks on one item in the list.
I have a ListView with text & image, represented in XML layout, and using simple StringAdapter.
I've implemented the above by doing this:
this.listViewSub.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(final AdapterView parent, final View view, final int position,
final long id) {
ImageView img = (ImageView) view.findViewById(R.id.unchkImg);
img.setImageResource(R.drawable.starchk);
I guess its not the right way to do it, but i don't have any idea how else to code it.
This code for some reason changes few random items in the list, and after one click i have about 4-5 items with icon changed.
Any idea how to solve it correctly?
Thanks
It's hard to tell without code, but my first guess is that as the views get recycled, if you don't reset the ImageView to use the default "unchecked" image in the getView method, each time you star an item the view will remain starred, even it is used for a different item. So your adapter should just reset the ImageView's image resource ; though in that case, you'll have to remember which items you starred in order to reset the ImageView correctly : set it to do the default drawable or to the starred one.
At last, after long search - i've found the answer in an article:
http://www.codegod.biz/WebAppCodeGod/Android-ListView-with-dynamic-Images-AID588.aspx
That was a tough one.

Unknown ListView Behavior

I'm currently making a SMS Application in Android, the following is a code snippet from Inbox Listactivity, I have requested a cursor from the contentresolver and used a custom adapter to add custom views into the list.
Now, in the custom view i've got 2 TextViews (tvFullBody,tvBody)...
tvFullBody contains the Full SMS Text while tvBody contains a short preview (35 characters)
The tvFullBody Visibility is by default set to GONE.
My idea is, when the user clicks on a list item, the tvBody should dissappear(GONE) and the tvFullBody should become visible (VISIBLE). On Clicking again, it should revert back to its original state.
//isExpanded is a BitSet of the size = no of list items...keeps track of which items are expanded and which are not
#Override
protected void onListItemClick(ListView l, View v, int position, long id) {
if(isExpanded.get(position))
{
v.findViewById(R.id.tvFullBody).setVisibility(View.GONE);
v.findViewById(R.id.tvBody).setVisibility(View.VISIBLE);
}else
{
v.findViewById(R.id.tvFullBody).setVisibility(View.VISIBLE);
v.findViewById(R.id.tvBody).setVisibility(View.GONE);
}
isExpanded.flip(position);
super.onListItemClick(l, v, position, id);
}
The Code works as it is supposed to :) except for an undesired sideeffect....
Every 10th (or so) List Item also gets "toggled".
eg. If i Expand the 1st, then the 11th, 21th list items are also expanded...Although they remain off screen, but on scrolling you get to see the undesired "expansion".
By my novice analysis, i'm guessing Listview keeps track of 10 list items that are currently visible, upon scrolling, it "reuses" those same variables, which is causing this problem...(i didn't check the android source code yet.)
I'd be gratefull for any suggestion, on how i should tackle this! :)
I'm open to alternative methods aswell....Thanks in advance! :)
Your diagnosis of the problem almost correct. What's happening is that Android is reusing the Views it creates to display the list to save memory. Instead of creating a new View for every item in your list, Android creates just enough to fill the screen, updating them to show the relevant data for the items which are currently visible.
So when you show tvFullBody when the user clicks on an item, when that View is re-used later tvFullBody is still visible.
You may have to write you own ListAdapter to make sure the Views are displayed how you want. It should be as simple as extending the ListAdapter you are currently using and overriding the getView() method to ensure that tvFullBody is hidden.

Minimum scroll amount when programmatically selecting ListItem in android ListView

refering to this question: how does scrolling in android listview work?
on change from state 2 to 3 the clicked listitem is increased in its size to show more information. if the clicked item was the last one on screen, the extended listitem is not fully visible because the new content flows out at the bottom of the screen.
my current solution is to call "setSelection(index)", if the last visible listitem was clicked. this results in a state were the selection is brought to the top of the screen. this is annoying because the listitem moves from bottom to top.
is there a way to avoid this? this means, is there something to let the listview know, that is should scroll only the minimum amount of pixels, so that the clickeditem is fully visible?
or have i to programm this functionality on my own?
Add a custom OnItemClickListener to the ListView. Implement OnItemClickListener.onItemClick like this:
public void onItemClick(final AdapterView<?> parent, final View view,
int position, long id) {
View hiddenContent = view.findViewById(R.id.hiddenContent);
hiddenContent.setVisibility(View.VISIBLE);
// At this point the layout hasn't be redone and you don't have reliable
// measurements on the view. It would be nice to do something after the view
// has gone through another layout
view.post(new Runnable() {
public void run() {
Rect r = new Rect();
view.getDrawingRect(r);
parent.requestChildRectangleOnScreen(view, r, false);
}
});
}
Whenever you click on a list item to show the hidden content the ListView control will go ahead and do whatever scrolling is needed (or no scrolling if none is needed) to completely show the row.

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