如何加载高分辨率图像

Question

I hava a high resolution(1188 * 17617 2.35MB) image and I want to load it in my Android APP. If I use WebView, the image can display. But it is indistinct. I open it with browser in Android OS, it also indistinct. If I use ImageView, it just display nothing.

Answer 1

You can scale down your bitmaps before loading them into the memory if they are too large. You can accomplish that by using BitmapFactory.Options and scale down as per your requirement.

public static Bitmap decodeSampledBitmapFromPath(String path, int reqWidth,
                int reqHeight) {

       final BitmapFactory.Options options = new BitmapFactory.Options();
       options.inJustDecodeBounds = true;
       BitmapFactory.decodeFile(path, options);

       options.inSampleSize = calculateInSampleSize(options, reqWidth,
                reqHeight);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        Bitmap bmp = BitmapFactory.decodeFile(path, options);
        return bmp;
    }

    public static int calculateInSampleSize(BitmapFactory.Options options,
             int reqWidth, int reqHeight) {

        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            if (width > height) {
                    inSampleSize = Math.round((float) height / (float) reqHeight);
            } else {
                    inSampleSize = Math.round((float) width / (float) reqWidth);
            }
        }
     return inSampleSize;
   }

Answer 2

Use the Picasso library. http://square.github.io/picasso/ .

It deals with everything for you including downloading, caching and most importantly for you downsampling via a resize function. It also works with a standard ImageView with very little code:

Picasso.with(context) .load(url) .resize(50, 50) .centerCrop() .into(imageView)