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Introduce RenderContext struct to pass scale information to renderers during layer preparation. This allows renderers to access resolved scale properties (such as input ranges/extents) when preparing data or building encoding/spec modifications. Changes: - Add RenderContext struct with scales field and helper methods: - new() - constructor - find_scale() - lookup scale by aesthetic name - get_extent() - extract numeric min/max from continuous scales - Update GeomRenderer trait signatures to accept RenderContext: - prepare_data() now takes context parameter - modify_encoding() now takes context parameter - modify_spec() now takes context parameter - Update all existing renderer implementations for new signatures (BarRenderer, PathRenderer, SegmentRenderer, RibbonRenderer, AreaRenderer, PolygonRenderer, ViolinRenderer, BoxplotRenderer) - Update call sites in mod.rs to create and pass context - Add unit test for RenderContext::get_extent() with 4 test cases Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Add ABLineRenderer that draws lines based on slope and intercept parameters using a clipping-based approach: - Uses global x-axis extent from scales (not per-panel) - Creates calculate transforms for x_min, x_max, y_min, y_max - Relies on Vega-Lite clipping for faceted plots - Uses rule mark for independent line segments - Removes slope/intercept from encoding (used in transforms only) Key implementation details: - modify_spec(): Creates transforms for constant x extent and computed y values based on slope * x + intercept - modify_encoding(): Removes slope/intercept, adds x/x2/y/y2 encodings using x_min/x_max/y_min/y_max fields - geom_to_mark(): Uses "rule" mark for AbLine - get_renderer(): Dispatches AbLine to ABLineRenderer Naming convention: x_min, x_max, y_min, y_max (consistent underscores) Grammar update: Add 'slope' and 'intercept' as valid aesthetic names for ABLine geom support. Includes integration test with 3 lines of different slopes, verifying transforms, encodings, and stroke encoding for color. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
thomasp85
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Feb 27, 2026
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A few general comments. I think it would be good to merge in the coord/project and handle conflicts in the layer PRs rather than the other way around so I'll give it another round when that is done
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A cute thing we could do once we get more serious about aggregations is to let hline/vline/rule have settings like |
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This PR advances #139.
Briefly, it adds segment, abline, hline and vline layers.
Most changes are straightforward.
The tricky bit was the abline layer, which required knowledge of the scale's x-limits to compute y. This is now captured in a
RendererContextstruct that carries a reference to the scales.Some examples are still a bit wonky because lines are repeated for every row in the data, but we can revisit these once #115 is implemented.