On Tue, 4 Mar 2025 21:43:17 GMT, Phil Race <p...@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.
>
> src/java.desktop/share/classes/javax/imageio/ImageTypeSpecifier.java line 923:
>
>> 921: int bufferedImageType = ((BufferedImage)image).getType();
>> 922: if (bufferedImageType != BufferedImage.TYPE_CUSTOM &&
>> 923: bufferedImageType != BufferedImage.TYPE_BYTE_INDEXED)
>> {
>
> So we'll no longer use a singleton IST for images with an ICM.
> I don't know how much that matters though. They probably aren't heavyweight
> compared to the image writing.
> The alternative - which I'll mention, which isn't the same as recommend - is
> to check if ColorModel.getTransparency() == OPAQUE before using the
> singleton, since we know that's the case it maps to.
>
> The BYTE_INDEXED case code in getSpecifier(..) isn't dead code, because it is
> still used in
> public static ImageTypeSpecifier createFromBufferedImageType(int
> bufferedImageType)
> In that case, there's not enough information to do anything except "pick
> one", so it is caveat emptor for callers of that API in such a case, and no
> need to do anything there.
>
> I'll have to run this through our testing.
Right.
If we value cached singletons: it'd be easy to break this up into 3 basic
cached ImageTypeSpecifiers (one for each Transparency constant: OPAQUE,
BITMASK, TRANSLUCENT). That would also satisfy the attached unit test and the
original TwelveMonkeys complaint. I started with what I thought was the
simplest proposal (in this PR), but I'm happy to explore other options if we
want.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/23884#discussion_r1980403056
