RFR: 8351108: ImageIO.write(..) fails with exception when writing JPEG with IndexColorModel [v4]

[Alexey Ivanov]

On Mon, 10 Mar 2025 18:22:49 GMT, Jeremy Wood <duke at openjdk.org> wrote:

>> Previously ImageTypeSpecifier treated all TYPE_BYTE_INDEXED as if they were opaque.
>> 
>> In this ticket's case: an ImageWriter received the wrong ImageTypeSpecifier and mistakenly indicated it *could* support a BufferedImage. But when the actual BufferedImage arrived (which was translucent), the ImageWriter threw an exception.
>> 
>> Instead:
>> Now the ImageTypeSpecifier accurately describes the given BufferedImage.
>
> Jeremy Wood has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8351108: changing Error to Exception, adding javadoc
>   
>   This is partly in response to:
>   https://github.com/openjdk/jdk/pull/23884#discussion_r1987733487

Marked as reviewed by aivanov (Reviewer).

test/jdk/javax/imageio/plugins/jpeg/JpegWriterWriteNonOpaqueIndexColorModelTest.java line 24:

> 22:  */
> 23: 
> 24: /**

Suggestion:

/*

I prefer regular block comments over javadoc-style comments for jtreg tags. Otherwise, IDE shows a warning for _dangling javadoc comment_, or warns about bad javadoc tags.

I don't insist here.

test/jdk/javax/imageio/plugins/jpeg/JpegWriterWriteNonOpaqueIndexColorModelTest.java line 55:

> 53:      * @param name the name of the Transparency constant
> 54:      * @param expectedWriteReturnValue the expected return value of <code>ImageIO.write(..)</code>
> 55:      * @return true if <code>ImageIO.write(..) == expectedWriteReturnValue</code>, or false otherwise.

Using `{@code ...}` is the preferred way to mark-up code fragments.

Perhaps, a javadoc is too much… The method isn't that long, and it's rather self-documenting.

test/jdk/javax/imageio/plugins/jpeg/JpegWriterWriteNonOpaqueIndexColorModelTest.java line 81:

> 79:                 }
> 80:             }
> 81:             IndexColorModel indexColorModel = new IndexColorModel(8, 256, gray, gray, gray, alpha);

Suggestion:

            }

            IndexColorModel indexColorModel = new IndexColorModel(8, 256, gray, gray, gray, alpha);

I think a blank line here will visually separate the block of preparing the arrays for `IndexColorModel` from their usage.

Creating an instance of `IndexColorModel` marks the start of the *real test*.

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

PR Review: https://git.openjdk.org/jdk/pull/23884#pullrequestreview-2671974299
PR Review Comment: https://git.openjdk.org/jdk/pull/23884#discussion_r1987882658
PR Review Comment: https://git.openjdk.org/jdk/pull/23884#discussion_r1987896914
PR Review Comment: https://git.openjdk.org/jdk/pull/23884#discussion_r1987901996