I'm working with the GridView example at Android Developers. I'm adapting the example code to display a Sudoku board using the GridView, 9x9 images. (It could be 9x9 text digits, but I've chosen images).
The example code contains this for setting the ImageViews (mThumbIds is an array of image resource ids):
// create a new ImageView for each item referenced by the Adapter
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) { // if it's not recycled, initialize some attributes
imageView = new ImageView(mContext);
imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setPadding(8, 8, 8, 8);
} else {
imageView = (ImageView) convertView;
}
imageView.setImageResource(mThumbIds[position]);
return imageView;
}
All good so far and it initialises fine.
I keep track of the imageViews for each cell so I can use them when I want to display a different image (by clicking on the image itself).
Again this works fine, except for position 0 (the first item in the GridView). This resolutely stays with the image set above from mThumbIds.
i.e.
I use
imageView.setImageResource(imgId)
to change images in different locations around the grid and they all change except for position 0.
The code runs with no exceptions, but the image never changes.
Is there something special about position 0? This is becoming a hair-loss scenario - any advice gratefully received.
Your getView code seems fine, but it's probably not being called. You need to trigger a redraw.
If your adapter is a BaseAdapter (or a subclass of BaseAdapter), call notifyDataSetChanged() on the grid's adapter to force the redraw.
Something like:
((BaseAdapter)mGridView.getAdapter()).notifyDataSetChanged();
Related
I working on my project with gridview layout, and the whole code is pretty identical to Android Developers example (I can't post links because of my low reputation, sorry).
Its works fantastic, when I need to fill screen with 3*3 or 4*4 (and etc) grids, but now I have to design my gridview with only 8 imageviews and I want to set the empty cell in the middle of GridView, just like that (click for images):
That is my current position:
This is what I need to do:
I have googled that a lot, but I can't find some example that shows how to implement that.
Have you any idea how can I solve that issue?
Set it to invisible -
imageView.setVisibility(View.INVISIBLE);
not works for me, because then I "lost" one of my imageViews.
Thanks a lot!
Let's consider you will always have an (x*x) number of items in your GridView, where x is an odd number bigger than 1, like 3 or 5. The index of the item that you want to hide is items.size()/2. Note that in Android, 9/2 = 4 and 25/2 = 12. So, we already know the index of the item that should be hidden.
Following, in the code, you just have to make your item View stay invisible when that your adapter.getView() method is called for that index. Here is that getView() portion of the code:
#Override
public View getView(final int position, View convertView, ViewGroup parent)
{
ViewHolder viewHolder;
LayoutInflater inflater = yourContext.getLayoutInflater();
if(convertView==null)
{
viewHolder = new ViewHolder();
convertView = inflater.inflate(R.layout.your_grid_item_layout, null);
convertView.setTag(viewHolder);
}
else
{
viewHolder = (ViewHolder) convertView.getTag();
}
if(position == yourItemsList.size()/2){
convertView.setVisibility(View.INVISIBLE);
}
else{
convertView.setVisibility(View.VISIBLE);
}
return convertView;
}
This will make your middle View invisible. The effect that you wanted.
Also note that your GridView number of lines has to be equal to the number of rows for this method to work.
You can always change the number of rows dynamically, according to the number of items that you have. In your Activity code, before gridView.setAdapter(), like this:
gridView.setNumColumns((int) Math.sqrt(myItemsList.size()));
Again I warn you that this code only works for GridView configurations of 3*3, 5*5, 7*7, and so on.
I have a similar problem to the one in this question: ListView and rows recycling problem
Above is solved. but same solution does not work for me.
I have a listview consisting of textviews. Each textview can contain variable number of images. I am getting images with html.imagegetter and I am using recycling in getview method of list adapter.
If there is one or more images in a textview, it will have a height to be able to fit its content. When this textview is recycled and new content does not fill the height defined before, then empty space will appear.
The problem is that I can't restore the textview height in getview because I dont know what height the next list item will have.
this is my getview:
public View getView(int position, View convertView, ViewGroup parent) {
final ViewHolder holder;
View rowView = convertView;
if (rowView == null) {
LayoutInflater inflater = context.getLayoutInflater();
rowView = inflater.inflate(resource, parent, false);
holder = new ViewHolder();
holder.imgAvatar = (ImageView) rowView.findViewById(R.id.imgAvatar);
holder.textDetails = (TextView) rowView.findViewById(R.id.textDetails);
holder.textPostTime = (TextView) rowView.findViewById(R.id.textPostTime);
holder.textPost = (TextView) rowView.findViewById(R.id.textPost);
rowView.setTag(holder);
} else {
holder = (ViewHolder) rowView.getTag();
}
holder.textDetails.setText(details.toString());
holder.textPostTime.setText(x.postTime);
holder.textPost.setText(Html.fromHtml(x.postBody, new URLImageGetter(holder.textPost, context), null, context));
return rowView;
}
this is row layout:
<TextView
android:ellipsize="none"
android:autoLink="web"
android:textColor="#000000"
android:id="#+id/textPost"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
THE PROBLEM: The listview recycling mechanism can't calculate the new height for used views according to its new contents.
Without recycling, it is too slow.
So, essentially your problem is with recycling the views. When your views get inflated from XML they look at the images and decide how tall to be. This works fine because the inflater can cause the height to be "wrap_content" aka however tall the tallest child component is - this is dynamic.
However, when your getview recycles the old views it (for some reason) isn't updating the height of the rows, and neither are you (which you never had to do before because the inflater handles it automatically from "wrap_content"). It would appear from what you described that you just get a row with whatever the height of the view happened to be set at previously (this previous value was set by the inflater automatically).
Your two solutions are:
Don't recycle the views - just inflate a new one every time. You will see a performance hit which will probably only be noticeable at lists with ~50 elements or more. If it is a small list this may be the easiest (code-wise) option, although there it will still operate slightly slower.
Keep recycling the views - if you pick this you will have to set the height of the row (or text view, whatever is determining it) yourself based on the image heights. This is doable but will require more work. I'd suggest
secret option 3 - normalize the image heights - If you would a.) like to continue recycling views but b.) don't want to write the code to set the row heights manually and c.) resizing the images wouldn't kill your app, you could use the setMaxHeight(int) method to make sure all of your images are the same height (or use a method like this to resize the images to a predetermined size)
Note: I am pretty sure (almost certain) that, normally, if height is set to "wrap_content" it would wrap to the new content size (since it normally updates the size when the content is updated). I couldn't say why this is not happening for you - it may be that something inside the "wrap_content" has its size set to a concrete value and thus isn't resizing, so the "wrap_content" isn't changing even though there is empty space.
Try using requestLayout on your image and textviews. It will help the listview recompute the height of recycled views.
I have a HorzontalScrollView with a LinearLayout inside. During Runtime I can add more LinearLayouts to the LinearLayout.
Now I have the problem that the Scrollview only scrolls a little bit and not smooth with one finger slide!
Does anyone have a solution for this problem?
HorizontalScrollView doesn't use an adapter that manages the list's memory, therefore it can't handle heavy (images, custom views, etc) lists.
You can use this Horizontal ListView http://www.dev-smart.com/archives/34 but make sure you don't write the on list item click method inside the getView, it will make the list scroll slow. Other than that, that's a great resource for a smooth horizontal list view.
You can also explore the Android view pager, which is also supported on lower Android versions using the compatibility pack: http://developer.android.com/sdk/compatibility-library.html
Edit - something like that in the adapter that inflates the XML you want (the linearLayout) and then populates every view with the relevant data.
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.chat_friends_list_item, null);
}
ImageView status = (ImageView)convertView.findViewById(R.id.status);
ImageView image = (ImageView)convertView.findViewById(R.id.image);
ImageView imageBorder = (ImageView)convertView.findViewById(R.id.image_border);
TextView title = (TextView)convertView.findViewById(R.id.title);
}
The problem was my parent Viewflow because it has stolen the swipe event! The HorizontalListView is too buggy for me! (Problems with size attributes)
However,thank you for your answer! ;)
I have a gridview set up with a list of images like this:
public int[] tb =
{ R.drawable.tb1, R.drawable.tb2, R.drawable.tb3, R.drawable.tb4,
R.drawable.tb5, R.drawable.tb6, R.drawable.tb7, R.drawable.tb8,
R.drawable.tb9, R.drawable.tb10, R.drawable.tb11, R.drawable.tb12,
R.drawable.tb13, R.drawable.tb14, R.drawable.tb15, R.drawable.tb16,
R.drawable.tb17, R.drawable.tb18 };
I know how to update a particular image by changing the position in the array e.g.
tb[2] = R.drawable.image;
then using
mAdapter.notifyDataSetChanged();
But my problem is, I want to update the image in the grid view and set the alpha so the image is transparent. Now with normal image view it is simple as doing
ImageView iv = (ImageView) findViewById(R.id.aTest);
iv.setAlpha(127);
But how do I apply to this to a specific image in the grid view. The images are stored as a set of ints and the images are applied using the ImageAdapter. So it means I can't just do
tb[0].setAlpha(127);
As it does not recognise it as an image view. I know I can set the imageView in the adapters Alpha, but that means all images will be transparent and I only want a select few to be transparent
So could anyone tell me how I can set it up so I can change one image in the list and make it transparent. I have the onClickItemListener set up so for time being trying to get it set up so when I click an item in the grid view, that image will become transparent.
Been trying lots of different solutions, but just can't seem to find anything that works. Would be very grateful if someone could point me in the right direction!!
There is no easy way to resolve this but here you go -
Modify your getView in your Adapter in this manner. (I am assuming you have a custom adapter, otherwise you will have to write one. See this example on how to do this)
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
//create new image view
} else {
// resuse
}
imageView.setImageResource(mThumbIds[position]);
// new code starts
if(clickedLocation == position){
imageView.setAlpha(alphaValue)
}
// new code ends
return imageView;
}
Store the position of the item from the onClickListener as clickedLocation
Now call invalidateViews() method on the GridView object.
Caveats: (Might not be the best way to go about it)
You will be redrawing the entire GridView everytime there is a click, you might see a flickering effect
If your resources are jpg or png then they need they need to be decoded each time
My probel is that images in my Gallery are bleeding in into each other once I begin scrolling towards the next image.
I am using a android.widget.Gallery connected to a custom adapter I extended from BaseAdapter.
The adapter's GetView() method is like this
public View getView(int position, View convertView, ViewGroup parent) {
ImageView i = new ImageView(mContext);
if (mImageBitmap != null && position < mImageBitmap.length)
i.setImageBitmap(mImageBitmap[position]);
return i;
}
Did you try using android:spacing ( in xml) or setSpacing(int spacing) (in code) on the Gallery?
I actually found the solution to my problem. In getView(), the ImageView I was returning had no background and thus the ImageViews would overlap. I set the background of the ImageView to black before returning it and it looks great
It seems the fading is added automatically and disabling through XML doesn't work.
However disabling programatically seems to work:
Gallery carousel = (Gallery)findViewById(R.id.image_carousel);
carousel.setHorizontalFadingEdgeEnabled(false);
If you have access to the Gallery instance, you can also call the following method to remove the bleed in area:
gallery.setUnselectedAlpha(1.0f);
This also removes the white-ish haziness of the Gallery view.