Hello,

Could you review the fix:
  bug: https://bugs.openjdk.java.net/browse/JDK-8029339
  webrev: http://cr.openjdk.java.net/~alexsch/8029339/webrev.00

This is a proposal to introduce an API that allows to create a custom multi resolution image.

I. It seems reasonable that the API should provide two basic operations:

1. Get the resolution variant based on the requested image width and height:
    - Image getResolutionVariant(int width, int height)

Usually the system provides the scale factor which represents the number of pixels corresponding to each linear unit on the display. However, it has sense to combine the scale factor and the current transformations to get the actual image size to be displayed.

 2. Get all provided resolution variants:
   - List<Image> getResolutionVariants()

  There are several uses cases:
- Create a new multi-resolution image based on the given multi-resolution image. - Pass to the native system the multi-resolution image. For example, a use can set to the system the custom multi-resolution cursor.

II. There are some possible ways where the new API can be added

 1. java.awt.Image.

  The 2 new methods can be added to the Image class. A user can override
the getResolutionVariant() and getResolutionVariants() methods to provide the resolution variants or there can be default implementations of these methods if a user puts resolution variants
  to the list in the sorted order.

To check that the image has resolution variants the following statement can be used: image.getResolutionVariants().size() != 1

The disadvantage is that there is an overhead that the Image class should contain the List object and not all
  images can have resolution variants.

 2. Introduce new MultiResolutionImage interface.

A user should extend Image class and implement the MultiResolutionImage interface.

  For example:
  ---------------------
    public class CustomMultiResolutionImage extends BufferedImage
            implements MultiResolutionImage {

        Image highResolutionImage;

        public CustomMultiResolutionImage(BufferedImage baseImage,
                BufferedImage highResolutionImage) {
super(baseImage.getWidth(), baseImage.getHeight(), baseImage.getType());
            this.highResolutionImage = highResolutionImage;
            Graphics g = getGraphics();
            g.drawImage(baseImage, 0, 0, null);
            g.dispose();
        }

        @Override
        public Image getResolutionVariant(int width, int height) {
            return ((width <= getWidth() && height <= getHeight()))
                    ? this : highResolutionImage;
        }

        @Override
        public List<Image> getResolutionVariants() {
            return Arrays.asList(this, highResolutionImage);
        }
    }
  ---------------------

The current fix adds the MultiResolutionImage interface and public resolution variant rendering hints.

Thanks,
Alexandr.

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