Converting image url to bitmap quickly

Question

I need to display the list of images from api in the list page. For that i used two approaches.

First Approach:
By converting the url to byte array

Answer 1

There is a library named Picasso. which can efficiently load images from url. it can also load image from the File. all you wanted to do , write a line of code.

example

Picasso.with(context) //Context
    .load("http://i.imgur.com/DvpvklR.png") //URL/FILE
    .into(imageView)//an ImageView Object to show the loaded image; 

It can also cache your image, so the loaded image could be able to load faster on the next time without wasting the data.

There are many more options available in Picasso. Here is the documentation

If you need rounded cornered bitmap

Picasso.with(mContext)
    .load("your-image-url-or-file-or-drawable")
    .transform(new RoundedTransformation(200, 0))
    .fit()
    .into(imageView);

RoundedTransformation.java

import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;

// enables hardware accelerated rounded corners
// original idea here : http://www.curious-creature.org/2012/12/11/android-recipe-1-image-with-rounded-corners/
public class RoundedTransformation implements com.squareup.picasso.Transformation {
    private final int radius;
    private final int margin;  // dp

    // radius is corner radii in dp
    // margin is the board in dp
    public RoundedTransformation(final int radius, final int margin) {
        this.radius = radius;
        this.margin = margin;
    }

    @Override
    public Bitmap transform(final Bitmap source) {
        final Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setShader(new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));

        Bitmap output = Bitmap.createBitmap(source.getWidth(), source.getHeight(), Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        canvas.drawRoundRect(new RectF(margin, margin, source.getWidth() - margin, source.getHeight() - margin), radius, radius, paint);

        if (source != output) {
            source.recycle();
        }

        return output;
    }

    @Override
    public String key() {
        return "rounded";
    }
}

Answer 2

There are open-source libraries which focus on loading image into an ImageView. Take for example of universal-image-loader, it is very easy to use, like:

// Load image, decode it to Bitmap and display Bitmap in ImageView (or any other view 
//  which implements ImageAware interface)
imageLoader.displayImage(imageUri, imageView);

or:

// Load image, decode it to Bitmap and return Bitmap to callback
imageLoader.loadImage(imageUri, new SimpleImageLoadingListener() {
    @Override
    public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
        // Do whatever you want with Bitmap
    }
});

or:

// Load image, decode it to Bitmap and return Bitmap synchronously
Bitmap bmp = imageLoader.loadImageSync(imageUri);

Take example of Volley, you can use it like this:

public void displayImg(View view){
    ImageView imageView = (ImageView)this.findViewById(R.id.image_view);
    RequestQueue mQueue = Volley.newRequestQueue(getApplicationContext()); 

    ImageLoader imageLoader = new ImageLoader(mQueue, new BitmapCache());

    ImageListener listener = ImageLoader.getImageListener(imageView,R.drawable.default_image, R.drawable.default_image);
    imageLoader.get("http://developer.android.com/images/home/aw_dac.png", listener);
    //指定图片允许的最大宽度和高度
    //imageLoader.get("http://developer.android.com/images/home/aw_dac.png",listener, 200, 200);
}

These libraries are used broadly, and more importantly, they are open-sourced. No need to implement functions like this repeatedly.

Answer 3

Try this

Hope this should help you.