RFR: 8277572: ImageStorage should correctly handle MIME types for images encoded in data URIs [v3]

[Michael Strauß]

> `com.sun.javafx.iio.ImageStorage` currently ignores the MIME image subtype specified for images encoded in data URIs. This should be improved as follows:
> 
> 1. If the specified image subtype is not supported, an exception will be thrown.
> 2. If the specified image subtype is supported, but the data contained in the URI is of a different (but also supported) image format, the image will be loaded and a warning will be logged. For example, if the MIME type is "image/jpeg", but the image data is PNG, the following warning will be generated:
> 
> 
> Image format 'PNG' does not match MIME type 'image/jpeg' in URI 'data:image/jpeg;base64,iVBORw0KGgoAAA...AAAElFTkSuQmCC'
> 
> 
> Also, the javadoc of `javafx.scene.image.Image` incorrectly states:
> 
>     94    * If a URL uses the "data" scheme, the data must be base64-encoded
>     95    * and the MIME type must either be empty or a subtype of the
>     96    * {@code image} type.
> 
> However, omitting the MIME type of a data URI is specified to imply "text/plain" (RFC 2397, section 2). Since the `com.sun.javafx.util.DataURI` class is implemented according to this specification, trying to load an image without MIME type correctly fails with an `ImageStorageException`: "Unexpected MIME type: text".
> 
> The solution is to fix the documentation:
> 
>       94    * If a URL uses the "data" scheme, the data must be base64-encoded
>     + 95    * and the MIME type must be a subtype of the {@code image} type.
>     - 95    * and the MIME type must either be empty or a subtype of the
>     - 96    * {@code image} type.

Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:

  Added documentation for MIME/data mismatch

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/676/files
  - new: https://git.openjdk.java.net/jfx/pull/676/files/73f1bb13..0167532b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=676&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=676&range=01-02

  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/676.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/676/head:pull/676

PR: https://git.openjdk.java.net/jfx/pull/676