feat: add --offset and --auto-offset for grid translation (issue #6)#26
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hai-pilgrim wants to merge 3 commits into
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feat: add --offset and --auto-offset for grid translation (issue #6)#26hai-pilgrim wants to merge 3 commits into
hai-pilgrim wants to merge 3 commits into
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--res WxH forces the output to an exact pixel resolution using NEAREST resampling (pixel-art safe). --aspectratio W:H center-crops the output to the given aspect ratio. --res takes precedence when both are given. spritegrid input.png --res 32x32 -o sprite.png spritegrid input.png --aspectratio 4:3 -o cropped.png Includes 18 unit tests covering parsing, resizing, cropping, and edge cases (identity, centering, portrait/landscape). Closes marksverdhei#4 Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
…erdhei#6 Adds two new ways to control where the grid origin sits: - `--offset XxY`: manually shift all sample centres right by X and down by Y pixels (e.g. `--offset 2x3`) - `--auto-offset`: auto-detect the grid phase from the gradient profile and apply the best-fit offset; improves alignment when the grid doesn't start at pixel 0 Internals: - `find_grid_offset(profile, spacing)` — O(spacing) scan to find the phase offset that maximises gradient energy at grid-line positions - `detect_grid_with_offset(image)` → `(grid_w, grid_h, offset_x, offset_y)` — wraps the existing detection and appends the detected phase - `create_downsampled_image` gains `offset_x`/`offset_y` params (default 0) - Auto-offset is **opt-in** to preserve backward-compatible output Tests: 18 new cases in `tests/test_grid_translation.py` Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Pillow 12 deprecates Image.Image.getdata in favour of get_flattened_data (slated for removal in Pillow 14). Update the two affected comparisons in test_grid_translation.py to silence the DeprecationWarning. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Refs #6
Adds grid translation — control over where sample centres are placed relative to the detected grid.
New flags:
--offset XxY— manually shift all sample centres right by X pixels and down by Y pixels (e.g.--offset 2x3). Useful when you know the grid doesn't start at pixel 0.--auto-offset— automatically detects the grid phase from the gradient profile and applies the best-fit offset. Improves alignment when grid lines are not at pixel 0.When to use: If the auto-detected grid produces slightly blurry or misaligned output,
--auto-offsetor a manual--offsetcan shift sample centres onto the true interior of each grid cell.Backward compatible:
--auto-offsetis opt-in. Default behaviour (no offset) is unchanged — all existing tests pass.Internals
find_grid_offset(profile, spacing)— O(spacing) phase scan that maximises gradient energy at multiples ofspacingdetect_grid_with_offset(image)→(grid_w, grid_h, offset_x, offset_y)— existing detection + phasecreate_downsampled_imagegainsoffset_x/offset_yparams (default 0)Test plan
tests/test_grid_translation.py:find_grid_offset: known-offset synthetic profiles, edge cases (empty, zero spacing, short profile)detect_grid_with_offset: 4-tuple shape, failed detection returns(0,0,0,0), offset in valid rangecreate_downsampled_imagewith offset: zero offset = default, positive/negative offset clamping, shift changes sampled values--offsetand--auto-offsetflags accepted without error🤖 Generated with Claude Code