Replace hardcoded fill/stroke/POI/label draw loops with a configurable
render graph that executes passes in z_order from lowest to highest.
New render_graph module:
- PassType enum: Background, Fill, Stroke, POI, Label, Selection, Debug
- PassConfig with z_order, enabled, min_zoom, max_zoom
- RenderGraph with enable/disable/zoom_range/set_z_order/execution_plan
- PassStats recording for per-frame diagnostics
- 16 unit tests covering ordering, gating, and stats
NigigMapView integration:
- draw_walk delegates to render_graph.should_execute() for each pass
- Records PassStats after each pass (tiles_drawn, features_drawn)
- Public API: render_graph(), enable_pass(), disable_pass(),
set_pass_zoom_range() for downstream configuration
Benefits:
- Easy insertion of new passes (3D buildings, terrain, traffic)
- Per-pass enable/disable at runtime
- Per-pass zoom culling (replaces hardcoded view_zoom >= 13.0)
- Debug visualization (show only one pass)
- Execution plan inspection for diagnostics
Phase 4 optimization: only recompute visible_tile_keys() when viewport
actually changes, avoiding unnecessary work every frame.
- TileScheduler::update_visible now takes &mut ViewportState
- Checks viewport.dirty before recomputing visible tiles
- Clears dirty flag after computation
- Skips recomputation when viewport unchanged (common case during idle)
- Adds tests for dirty flag behavior
This reduces per-frame CPU work when the map is stationary or during
non-interactive rendering.
Phase 1 Step 4 of map rewrite plan: extract label scratch buffers and
placement methods into dedicated LabelState struct.
- Create label_state.rs with LabelState owning all scratch buffers
- Move place_and_draw_labels, collect_label_candidates, build_label_placement
from view.rs to LabelState
- Wire LabelState into NigigMapView as #[rust] field
- Reduce view.rs from 1497 to 1100 lines (-27%)
- Label logic now isolated and testable independently
- Preserves all existing behavior and performance characteristics
This completes Phase 1 of the map rewrite plan. All subsystem extractions
are now complete: ViewportState, TileCache, TileScheduler, RenderPass,
and LabelState.
