[OpenJDK 2D-Dev] [11] RFR: [JDK-4954348]: JPGWriter.getNumThumbnailsSupported does not return -1 when passing null values

[Jayathirth D V]

Hi Prahalad,

Change looks fine.
Test case works properly before and after the code change.

Since we are touching getNumThumbnailsSupported() function and it is only overridden in JPEGImageWriter we can add override annotation for the same.

Thanks,
Jay

-----Original Message-----
From: Prahalad Kumar Narayanan 
Sent: Friday, March 23, 2018 1:40 PM
To: 2d-dev
Subject: [OpenJDK 2D-Dev] [11] RFR: [JDK-4954348]: JPGWriter.getNumThumbnailsSupported does not return -1 when passing null values

Hello Everyone

Good day to you.

Request your time to review a simple fix for the bug
    Bug: JDK-4954348 (https://bugs.openjdk.java.net/browse/JDK-4954348)
    Title: JPGWriter.getNumThumbnailsSupported does not return -1 when passing null values

Root Cause:
    . As per ImageWriter specification, the method- getNumThumbnailsSupported, should return -1 when invoked with insufficient data.
    . However, the method's implementation in JpegImageWriter returns 0 instead of -1 in this use-case. 

Information on the fix:
    . The logic within concerned method of Jpeg image writer requires one of the two inputs- ImageTypeSpecifer (or) IIOMetadata.
    . If both the required inputs are 'Null' the method has insufficient data & thus cannot validate. 
    . A simple check is now added in the method to detect this use-case and return -1 as recommended in the specification.

Kindly review the changes at your convenience
Link: http://cr.openjdk.java.net/~pnarayanan/4954348/webrev.00

Thank you
Have a good day

Prahalad N.