# Objective
- So far only full buffer reads were supported. This adds the ability to
read a part of a buffer.
## Solution
- Allow passing in a start offset and a number of bytes to read when
creating the `Readback` component.
- I also removed the unused `src_start` and `dst_start` fields from
`ReadbackSource` as they were always 0.
## Testing
- Did you test these changes? If so, how?
I extended the example to also demonstrate partial reads.
- Are there any parts that need more testing?
Can't think of any.
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
Run the `gpu_readback` example. It now also reads and prints a partially
read buffer.
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
Only tested on Linux.
---
## Showcase
Example output:
<details>
<summary>Click to view showcase</summary>
```
2025-07-14T14:05:15.614876Z INFO gpu_readback: Buffer [257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272]
2025-07-14T14:05:15.614921Z INFO gpu_readback: Buffer range [261, 262, 263, 264, 265, 266, 267, 268]
2025-07-14T14:05:15.614937Z INFO gpu_readback: Image [257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270, 271, 272, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
```
</details>
3ce2f46ae5