Hi I want to show the images in listview when user scroll the list.
I retrieved the image from database(blob) not from web service.
for example
I have an 40 items in the list view and in my mobile screen 10 item is visible. when i scroll the list it load the next images. i don't want to load the 40 images concurrently.
list will show images between Fisrt Visible Position and Last Visible Position.
Like in a twitter app the images first blank when user scroll then it load in the listview
Thanks in advance.
The solution you finding is called Lazy Loading Adapter, this tutorial will work as you want check this link, this loads images in lazy manner.
Related
I'm creating an android book that use data from database(sqlite) and has six season.
my data is about 1MB and for loading data on listview is slow.I wanna to put a dynamic listview for my project that load 10 item on listview with scrolling each time.
please help me
ListView actually keep in memory items only visible for users - check it for better understanding - http://android.amberfog.com/?p=296.
I think you are talking about lazy loading data from sqlite, so just fetch next 20 (or whatever) items when user scrolled to last item.
I recommend you to switch to RecyclerView. Please check that article for implementation of endless scrolling with RecyclerView.
I have a list which I use recyclerView to display. Each row in the list displays an image that is downloaded from a remote server. In order to speedup the display of the list I am downloading the images in the background. Each time the bind() wants to display the image I call a method that starts an asynchronous task that download the image and in the onPostExecute() method I call setImageBitmap() of the image to display the bit-mapped downloaded.
The problem is as follows
As I scroll down, the recyclerView loads more images that fits the screen and when the setImageBitmap() is called the list jumps up, so that the last 1 or 2 items in the list almost never displayed.
When I disable the call to setImageBitmap() there is no problem in displaying the last items (the list now is without images), and scrolling up and down the list.
The problem also shows up when I scroll down very slow. I limited the screen to show only 4 items, and as I scroll down to the 6th or 7th item suddenly the display jumps and displays again from item 2 to 5.
What is going on there and how can I make the display to scroll smoothly and without jumping all over?
There problem here comes to the fact your recycler view at the time it is inflated has size X, when you load your image the size changes but the LayoutManager is not aware of this change, hence it won't update your view.
You should post a snippet of your code, it will help to clarify.
I want to load list of images from the server.
1) I prefer if I can use the screen space optimally by adjusting the image columns.
2) User should be able to click each image individually and navigate to the next screen.
3) Further, when the screen first loads, I would like to load few image slots with loading image and replace them when we get the data from the server. It will add additional image slots as well (i.e after replacing first few) based on the data. so that user can see we are waiting for the data.
See below
What I already tried.
1) Using custom list view and adapter approach (http://www.androidhive.info/2012/02/android-custom-listview-with-image-and-text/), I created a layout with two listviews, acting as two columns and loaded images each one separately. Issue is user will see two scrollbars when image list is long. Also cannot adjust the number of columns based on screen size.
2) Same custom list view with, row layout having two imageviews. Issue here is user cannot click individual imageview.
I was not able to replace images to implement the third requirement.
How can I implement this. Are there any resources/controls I can use.
Thanks
Pa
I would probably use a gridview and an adapter for the gridview items. Just load a local image for loading to the imageview of the griditems and replace them with the images from the server
I am new Android developer. I want to achieve the following: On a particular screen (Activity) I have a grid view with images being set onto it. I have hundreds of thumbnail images coming from a server via http request. Now I don't want the gridview (with 4 columns in one row) to load the images in one go. Instead I want images to be loaded one row at a time (4 images), with other tiles of the grid view showing progess bar. Also when only few images are displayed the user should still be able to scroll the gridview vertically and thereby displaying empty gridview frames or tiles but if the scrolling is paused the frames or tiles of gridview are again loaded one row at a time.
I am looking for ideas to achieve this.
Thanks in advance for your responses.
In your Adapter's getView method set the image with a indefinite progress spinner.
After that start an AsyncTask to download the image if its not present in the object returned by getItem. Pass the item's position to the asynctask.
In AsyncTask's onPostExecute set the image to the view at position and hide the progress spinner.
Downloading the image in AsyncTask will ensure that your gridview is filled with items(empty) and responds to scrolling.
I am building a android aplication which will be consuming a json file from the internet. This json file contains a list of news from a particular website. Each json object contains information such like title, summary, descripition and web links for the news thumbnail and the original image.
I will be displaying in a listview three information: the news thumbnail, the title and the summary. Here resides my problem. I dont want to load all thumbnails from the internet if they wont be displayed. What I am trying to say is that why download a thumbnail from the 30th news if the user wont scroll down the image. So, i will, initially only download the thumnails from those news that are being displayed in the screen and when the user scrolls down to see more news, as soon as the list item appers to the screen i want to download the image and then display.
Is there a way to achieve this? Is it possible to find out if the list item is on the screen? I have been searching all over the internet for a solution for this but i am running out of ideas.
Thanks
T
You essentially want to lazy load your images. This will only load images that are currently being shown and as you scroll through the list view it will go and fetch those currently shown images.