On Wed, 10 Jun 2026 05:15:16 GMT, Jayathirth D V <[email protected]> wrote:
> We use `Math.ceil()` at 2 places in BMPImageWriter and both of them are under > encodeRLE4() function. Also they are used only under absolute mode of > encoding. > > First usage `(int)Math.ceil((absVal-1)/2)` is while encoding data in each > scanline. Here absVal always starts with 3 and increments by 2, so > `Math.ceil()` is basically a no-op here and its usage can be removed. > > Second usage `(int)Math.ceil((absVal+1)/2)` is while encoding end of scanline > data. Here absVal can be even and we need to use `Math.ceil()` properly > otherwise padding will not be added properly. I have added regression test > which actually identifies this issue and it creates a corrupt encoded BMP > image. In this regression test we have odd number of distinct pixels at the > end of scanline and encoding without proper padding corrupts next scanline of > data. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). This pull request has now been integrated. Changeset: acbedab7 Author: Jayathirth D V <[email protected]> URL: https://git.openjdk.org/jdk/commit/acbedab7198b4c1de2edd8960bcd6da644a15828 Stats: 116 lines in 2 files changed: 113 ins; 0 del; 3 mod 8384512: BMPImageWriter uses integer division before Math.ceil causing incorrect calculation Reviewed-by: azvegint, prr ------------- PR: https://git.openjdk.org/jdk/pull/31447
