RFR: 8352407: PixelInterleavedSampleModel with unused components throws RasterFormatException: Incorrect pixel stride [v2]

[Sergey Bylokhov]

On Wed, 19 Mar 2025 13:06:56 GMT, Nikita Gubarkov <ngubarkov at openjdk.org> wrote:

>> 8352407: PixelInterleavedSampleModel with unused components throws RasterFormatException: Incorrect pixel stride
>
> Nikita Gubarkov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   The previous approach was wrong for non-pixel interleaving.
>   
>   Just align the buffer size to the pixel stride instead, should be better.

src/java.desktop/share/classes/java/awt/image/ComponentSampleModel.java line 285:

> 283:          // Align to the pixel stride.
> 284:          size = (size + pixelStride - 1) / pixelStride * pixelStride;
> 285: 

Some thoughts I’d like to mention to ensure I understand the problem:

This method should return the number of bytes required to store the image with given parameters—width, height, pixel stride, and scanline. It seems that the calculation could follow this approach:

**starting offset + pointer to the last pixel + pixelStride**

Is that a correct assumption?

I have doubts that the logic in this method actually calculates the size properly, especially this line:


int val = pixelStride * (width - 1);
size += val;

It seems like it should be:

int val = pixelStride + pixelStride * (width - 1);

or simply:

int val = pixelStride * width;

Or am I missing something?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24111#discussion_r2024148158