Develop Reference

how to display images (base64 to bitmap) to Image Slider?

can you give me some reference about imageSlider from json?
I can already convert base64 to bitmaps using listView. but I am confused about how to display the results of the conversion into imageSlider.
data:[{"ID": 1,"Title": "Ads","Image":"data:image\/jpeg;base64........"]

This method can help:
private void setExistImage(ImageView imageView, String base64String){
if (!base64String.isEmpty()) {
byte[] bytes = Base64.decode(base64String, Base64.DEFAULT);
imageView.setImageBitmap(BitmapFactory.decodeByteArray(bytes, 0, bytes.length));
}
}

Maybe you can give a try to retrofit or picasso they are most popular libraries used in Android nowadays

Bitmap download for numerous images causing issue

I am learning Android dev. and am developping a Hearthstone app using a Hearthstone API for fun.
My users can search for specific cards and now I wish to implement a Card Displayer that displays cards by their type, and lets the user swipe right or left to display the next one in my JSONArray. My API request gives me one and each JSONObject has an img attribute with the cards image URL.
Therefore, when the user swipes I am doing the following:
// Swipe right -> number - 1 (Previous page)
// Swipe left -> number + 1 (Next page)
public void displayCardNumber(int number) {
APIRequests apiRequests = new APIRequests();
try {
// Gets the JSONObject at 'number' and retrieves its img URL.
JSONObject card = (JSONObject) cardsArray.get(number);
String currentImageURL = (String) card.get("img");
// Here is where my problem is.
Bitmap bitmap = apiRequests.getImageBitmap(currentImageURL);
if (bitmap != null) {
setNewImage(bitmap);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
But apiRequest.getImageBitmap(URL) is where I have a problem.
I must download the image in order to display it, but not only does the following block of code not work when I download more than one image, I must also find an efficient way of displaying my cards (that requires background download perhaps?).
// Returns the image's bitmap using the URL
protected Bitmap getImageBitmap(String currentImageURL) {
try {
Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(currentImageURL).getContent());
return bitmap;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
Why can't I download more than 1 image? Is my way of getting my Bitmap false?
Thank you.

Use Glide https://github.com/bumptech/glide .This is faster.
Bitmap theBitmap = Glide.
with(this).
load(imgUrl). //image url as string
asBitmap().
into(100, 100). // Width and height
get();
You can also use it with another way like this:
Glide.with(context).load(url) // image url
.thumbnail(0.5f)
.crossFade()
.diskCacheStrategy(DiskCacheStrategy.ALL)
.placeholder(imgId) // If no image found the imgId is the default image id for the imageView
.into(imageView); // imageView to show the image

I have found a solution,
In order to load my image and display it I now use a library called Android Universal Image Loader that lets me do the following:
// Load image, decode it to Bitmap and display Bitmap in ImageView
ImageLoader imageLoader = ImageLoader.getInstance();
ImageView i = (ImageView)view.findViewById(R.id.cardDisplay);
imageLoader.displayImage(currentImageURL, i);
I retrieve the correct URL in my AsyncTask's doInBackground and display it with the library's method.

how do I transform a string of url's into drawable?

I currently have an arraylist as follows:
private void loadImages() {
images = new ArrayList<>();
images.add(getResources().getDrawable(R.drawable.imag1));
images.add(getResources().getDrawable(R.drawable.imag2));
images.add(getResources().getDrawable(R.drawable.imag3));
}
I want to be able to convert a url into these drawables such that:
drawable1 = "http.someimage.com/image.png"
drawable2 = "http.someimage.com/newimage.png"
followed by
private void loadImages() {
images = new ArrayList<>();
images.add(getResources().getDrawable(drawable1));
images.add(getResources().getDrawable(drawable2));
...etc }
Is there any easy way to go around this? I definitely want to stick to drawables ,but I cant find any way to convert a url to drawable
Any ideas? Thanks!

If you have a URL of the picture you need to download it first.
You can't "convert" a URL into a drawable.
you need something like this:
URL url = new URL("http.someimage.com/image.png");
Bitmap bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
Then if you need to add the image into an ImageView object you can call the method .setImageBitmap(bmp).
Otherwise there are ways to extract a Drawable object from the Bitmap
you can check this previous answer. then once you have the drawable you can add it to your arraylist.
Hope I got your question right
P.S.: be sure not to do this on main thread since it is a network operation! use a thread or an asynctask

Set ImageView using URL

I have an Image on my server. The URL for the image is something like:
http://www.mydomain.com/123456uploaded_image.jpg
I am trying to set this image to my ImageView. Here is the code that I tried:
try{
String url1 = myeventimagearray[position];
URL ulrn = new URL(url1);
HttpURLConnection con = (HttpURLConnection)ulrn.openConnection();
InputStream is = (InputStream) con.getInputStream();
Bitmap bmp = BitmapFactory.decodeStream(is);
if (null != bmp)
iveventimg.setImageBitmap(bmp);
else
Log.i("Image","Not set");
} catch(Exception e) {
e.printStackTrace();
}
When I try this, my imageview is empty, i.e., it doesn't set the image view and i get this System err in my logcat:
java.lang.ClassCastException: libcore.net.http.FixedLengthInputStream cannot be cast to com.example.eventnotifier.Base64$InputStream
Base46.java is a file I found from the internet that Encodes and decodes to and from Base64 notation.
Any idea why I'm getting this System.error?
Thank you

Use URlImageViewHelper, it will take care of loading url into imageview.
Refer this
It will take care of caching, loading in background etc. by itself.

This is not an easy answer but you should use a caching system.
See https://github.com/chrisbanes/Android-BitmapCache for an excellent one!
Simply swap the ImageView for NetworkCacheableImageView and then use loadImage( "http://....", true );

You are likely getting an exception because you are trying to do network io on the main thread. Consider using a loader or an AsyncTask to load your image.
Check your logs, I bet you are printing a stack trace in the auto generated catch block.
new Thread(new Runnable() {
public void run() {
final Bitmap b = bitmap = BitmapFactory.decodeStream((InputStream)new URL(myeventimagearray[position]).getContent());
iveventimg.post(new Runnable() {
public void run() {
iveventimg.setImageBitmap(b);
}
});
}
}).start();

Use Picasso to fetch image from url. Implement 'com.squareup.picasso:picasso:2.71828' in build.gradle and in java
Picasso.get()
.load(url) // http://www.example.com/123456uploaded_image.jpg
.resize(50, 50)
.centerCrop()
.into(imageView)

Out of memory loading imageViews

I have a scrollview which has small thumbnails of images loaded via AsyncTask and throws the image URL unto a imageView.
They are added dynamically and then on top, is a main imageView which holds the image of the thumbnail you clicked.
Everything runs great until you have about 10+ images in the thumbnails...
I am loading the mainImage url via the same way as the thumbnails, so when they click an image in the thumb, it loads it up top.
I am recycling the bitmap in the method itself, but it seems to be running out of memory and crashing when loading more than 10 images (thumbnails load ok, but crashes when i click to load the main image)
any help appreciated
this is the code i am using the load the images (thumbnails + main):
private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
ImageView bmImage;
public DownloadImageTask(ImageView bmImage) {
this.bmImage = bmImage;
}
protected Bitmap doInBackground(String... urls) {
String urldisplay = urls[0];
Bitmap mIcon11 = null;
try {
InputStream in = new java.net.URL(urldisplay).openStream();
mIcon11 = BitmapFactory.decodeStream(in);
} catch (Exception e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return mIcon11;
}
protected void onPostExecute(Bitmap result) {
bmImage.setImageBitmap(result);
}
}

just implement this on ur image ... it will reduce ur image by 4 times
public static Bitmap getImage(byte[] image) {
BitmapFactory.Options config = new BitmapFactory.Options();
config.inPreferredConfig = Bitmap.Config.RGB_565;
config.inSampleSize = 4;
return BitmapFactory.decodeByteArray(image, 0, image.length,config);
}

You should read the two following Android official tutorials. They will teach you how to load large bitmap efficiently, and they provide working code samples that we use in our production apps
Displaying Bitmaps Efficiently
Loading Large Bitmaps Efficiently

you are not closing the input stream. So all the time when images urls executed input stream objects created which are expensive and causing you OutofMemoryError. add below code after catch block.
in.close();
in = null;

You probably have to work with some sort of cache strategy for the bitmaps, try having a look on the library Universal Image Loader, it works very well for what you need
Recycling bitmaps by yourself should only be done when you know for sure that it won't be used anymore.

Try to resize the bitmap to a smaller size (with a factor like 1.5 example: width=widt*1.5)
then strech(fit xy or whatever) in your view.it will lower the quality of the image due to the factor you decide. it is a quick dirty way. also making bit map rgb like Niun Goia mentions works well.

You shouldn't be using a ScrollView for this. You should be using a ListView. When you use a ScrollView (with a LinearLayout or something like that inside it), all the elements in the list (no matter how big it is) will try to be loaded immediately. Try a ListView instead (which is made for that exact reason, it only loads in memory the ui elements of the rows that are visible).

You can use android:largeHeap="true" to request a larger heap size
answer

I use this..
Options opt = new Options();
opt.inPurgeable = true;
opt.inInputShareable = true;
opt.inPreferredConfig = Bitmap.Config.RGB_565;