ImageView中的图像质量

Question

I have a list of bitmap images in asset folder to display(using ViewPager). I tried to set the width and height of the image based on screen-size(using layout params). But the image quality gets disturbed. How to make the image quality better?

 Drawable drw = Drawable.createFromStream(getAssets().
                            open("Parts/"+drawables[i]),null);

Here, drawables[i] is the String[] (say like ball.bmp and "Parts" is the subfolder of asset). Now, I have set the image in imageview as,

imageView.setBackgroundDrawable(imageArray[position]);

The image looks good in mobile but looks stretched in tab.

Answer 1

Try this; decode your image and find the correct scale value:

private Bitmap getBitmap(String url) {
    // from web
    try {
        Bitmap bitmap = null;
        URL imageUrl = new URL(url);

        HttpURLConnection conn = (HttpURLConnection) imageUrl
                .openConnection();
        conn.setConnectTimeout(1000);
        conn.setReadTimeout(1000);
        conn.setInstanceFollowRedirects(true);
        InputStream is = conn.getInputStream();
        OutputStream os = new FileOutputStream(f);
        Utils.CopyStream(is, os);
        os.close();
        bitmap = decodeFile(f);
        return bitmap;
    } catch (Exception ex) {
        ex.printStackTrace();
        return null;
    }
}

// decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f) {
    try {
        // decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f), null, o);

        // Find the correct scale value. It should be the power of 2.
        final int REQUIRED_SIZE = 150;
        int width_tmp = o.outWidth, height_tmp = o.outHeight;
        int scale = 1;
        while (true) {
            if (width_tmp / 2 < REQUIRED_SIZE
                    || height_tmp / 2 < REQUIRED_SIZE)
                break;
            width_tmp /= 2;
            height_tmp /= 2;
            scale *= 2;
        }

        // decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize = scale;
        return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
    } catch (FileNotFoundException e) {
    }
    return null;
}