[dajiaohuang]

Fixes IMAGING-388.

What

PNG scanline sizing used 32-bit multiplication for bitsPerPixel * width and rounded the result to bytes with another int expression. For the reported 536,870,921-pixel, 8-bit grayscale row, the product wraps to 72 bits and produces a 9-byte row buffer. Decoding then indexes beyond that buffer.

Compute scanline size in long, reject results that cannot be represented as a Java array length with ImagingException, and use long arithmetic for per-sample offsets. BitParser now reports an out-of-row sample as ImagingException rather than leaking ArrayIndexOutOfBoundsException.

Tests

• Regression verifies 536,870,921 grayscale pixels require a 536,870,921-byte row without allocating that buffer.
• Regression verifies unrepresentable scanline lengths and out-of-row/overflowing sample offsets fail with ImagingException.
• Default Maven build (mvn): BUILD SUCCESS; 1,265 tests, 0 failures, 0 errors, 7 skipped. The task-local checkout was normalized to the repository's LF source convention for Checkstyle.

Contribution checklist

• Read the contribution guidelines.
• Read the ASF Generative Tooling Guidance.
• AI use: OpenAI Codex (gpt-6-luna) assisted with source analysis, implementation, and regression tests. Human operator: dajiaohuang.
• Ran the default Maven build successfully.
• Added behavioral regression tests.
• This description explains the issue and change.
• Commit subject and body identify the issue and summarize the change.