Question

How can I load drawable from InputStream (assets, file system) and resize it dynamically based on the screen resolution hdpi, mdpi or ldpi?

The original image is in hdpi, I only need resizing for mdpi and ldpi.

How does Android do dynamic resizing of the drawables in /res?

Answer 1

Found it:

  /**
   * Loads image from file system.
   * 
   * @param context the application context
   * @param filename the filename of the image
   * @param originalDensity the density of the image, it will be automatically
   * resized to the device density
   * @return image drawable or null if the image is not found or IO error occurs
   */
  public static Drawable loadImageFromFilesystem(Context context, String filename, int originalDensity) {
    Drawable drawable = null;
    InputStream is = null;

    // set options to resize the image
    Options opts = new BitmapFactory.Options();
    opts.inDensity = originalDensity;

    try {
      is = context.openFileInput(filename);
      drawable = Drawable.createFromResourceStream(context.getResources(), null, is, filename, opts);         
    } catch (Exception e) {
      // handle
    } finally {
      if (is != null) {
        try {
          is.close();
        } catch (Exception e1) {
          // log
        }
      }
    }
    return drawable;
  }

Use like this:

loadImageFromFilesystem(context, filename, DisplayMetrics.DENSITY_MEDIUM);