RFR: 8358623: Avoid unnecessary data copying in ICC_Profile

[Sergey Bylokhov]

On Wed, 4 Jun 2025 23:39:05 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

> This PR simplifies several aspects of the ICC_Profile class:
> 
> - [Change 1](https://github.com/openjdk/jdk/pull/25650/commits/426a608b1df9e39e221d05e7374a3fecf6e6cf30):
>     The ICC_Profile.getInstance(byte[] data) method used to copy the profile header for validation. This copy appears redundant, as the original data array is used later anyway. This logic was originally introduced by [JDK-8347377](https://bugs.openjdk.org/browse/JDK-8347377).
> 
> - [Change 2](https://github.com/openjdk/jdk/pull/25650/commits/4035c8b1f7e1dcbc9941ead939218bba47b0a2fe):
>     In some places, the code retrieves the profile header using getData(icSigHead), which always creates a new array. It is now replaced with private getData(cmmProfile(), icSigHead) to avoid unnecessary copying. To clarify the purpose of the private method, I have added documentation.
> 
>  - [Change 3](https://github.com/openjdk/jdk/pull/25650/commits/96ad456593de3dd68c3ae6840fffee7bac68bc0c):
> After Change 2, static analysis tools began reporting a potential NPE when using getData(cmmProfile(), icSigHead), since it may return null. To address this, the internal implementation of getData was updated to always return a non-null value or throw an exception. The public method now catches this exception and returns null, as required by the specification. **Note**: this potential NPE is not a regression introduced by any changes, it simply became easier for tools to detect due to the simplified code.
> 
> @prrace @honkar-jdk please take a look

src/java.desktop/share/classes/java/awt/color/ICC_Profile.java line 814:

> 812:             if (type == ColorSpace.TYPE_GRAY) {
> 813:                 return new ICC_ProfileGray(p);
> 814:             } else if (type == ColorSpace.TYPE_RGB) {

The above checks are moved to the corresponding constructors.

test/jdk/java/awt/color/ICC_Profile/CheckVersions.java line 61:

> 59:         }
> 60:     }
> 61: }

Also added a test for the changed methods, since they were not covered by any jtreg tests.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25650#discussion_r2130946342
PR Review Comment: https://git.openjdk.org/jdk/pull/25650#discussion_r2130957346