feat(selection): separate selection geometry from image content processing

- Introduced a new design for selection rasterization that decouples the selection geometry from the image content, ensuring that the SelectionMask is independent of the source image's alpha and color.
- Updated the `rasterize_selection_path` function to only accept selection paths and image dimensions, removing parameters related to source alpha and alpha thresholds.
- Implemented a new approach for handling selection paths using non-zero winding fill, ensuring overlapping areas are preserved.
- Enhanced performance by utilizing a scanline algorithm for rasterization, significantly reducing processing time for high-resolution images.
- Updated internal documentation and added comprehensive tests to validate the new behavior and performance improvements.
- Ensured backward compatibility by maintaining existing interfaces where necessary while introducing breaking changes in the selection processing logic.

tests/test_cutout_interaction.py

@@ -1,9 +1,8 @@
+import json
 import sys
 from pathlib import Path
 from types import MethodType, SimpleNamespace
 
-import bpy
-
 SOURCE_ROOT = Path(__file__).parents[1] / "src"
 sys.path.insert(0, str(SOURCE_ROOT))
 
@@ -83,6 +82,15 @@ def test_cutout_pie_passes_image_lasso_options_to_all_ai_shapes(monkeypatch):
     context = cutout_context(window_manager, mesh_detail="MEDIUM", generate_normal=True)
     source = cutout_source(size=(4096, 2048))
     monkeypatch.setattr(interaction, "ai_ready", lambda: True)
+    serialized = []
+    original_to_json = SelectionPath.to_json
+
+    def record_to_json(selection_path):
+        value = original_to_json(selection_path)
+        serialized.append(value)
+        return value
+
+    monkeypatch.setattr(SelectionPath, "to_json", record_to_json)
 
     interaction.open_shape_pie(
         context,
@@ -103,6 +111,12 @@ def test_cutout_pie_passes_image_lasso_options_to_all_ai_shapes(monkeypatch):
     ]
     assert all(call[2].refine_selection for call in window_manager.pie.calls)
     assert all(call[2].generate_normal for call in window_manager.pie.calls)
+    assert len(serialized) == 1
+    assert set(json.loads(serialized[0])) == {"points", "invert"}
+    assert all(
+        call[2].selection_path_json == serialized[0]
+        for call in window_manager.pie.calls
+    )
     assert all(
         SelectionPath.from_json(call[2].selection_path_json).invert
         for call in window_manager.pie.calls
@@ -132,12 +146,7 @@ def test_cutout_mesh_detail_maps_to_denser_sampling():
 
 
 def test_cutout_reuses_image_lasso_gesture_and_double_click_selects_all(monkeypatch):
-    bpy.ops.wm.read_factory_settings(use_empty=True)
-    image = bpy.data.images.new("Source", width=320, height=180)
-    source = bpy.data.objects.new("Source", None)
-    source.empty_display_type = "IMAGE"
-    source.data = image
-    bpy.context.collection.objects.link(source)
+    source = cutout_source(size=(65536, 32768))
     window_manager = WindowManager()
     context = cutout_context(window_manager)
 
@@ -145,15 +154,32 @@ def test_cutout_reuses_image_lasso_gesture_and_double_click_selects_all(monkeypa
         cutout_main, "resolve_image_edit_click", lambda *_args: (source, True)
     )
     monkeypatch.setattr(cutout_main, "video_total_frames", lambda _image: 1)
+    monkeypatch.setattr(cutout_main, "require_image_empty", lambda _name: source)
     monkeypatch.setattr(cutout_main, "apply_selection_settings", lambda *_args: None)
-    monkeypatch.setattr(cutout_main, "validate_cutout_selection", lambda *_args: None)
+    monkeypatch.setattr(cutout_main, "serialize_matrix", lambda _matrix: "matrix")
+    monkeypatch.setattr(
+        cutout_main,
+        "image_rgba",
+        lambda *_args: (_ for _ in ()).throw(AssertionError("unexpected pixel read")),
+    )
+    monkeypatch.setattr(
+        cutout_main,
+        "rasterize_selection_path",
+        lambda *_args, **_kwargs: (_ for _ in ()).throw(
+            AssertionError("unexpected Selection rasterization")
+        ),
+    )
 
     operator = SimpleNamespace(
         full_image=True,
         refine_selection=False,
         report=lambda *_args: None,
     )
-    operator.execute = MethodType(cutout_main.SelectCutoutSelection.execute, operator)
+    source.matrix_world = object()
+    operator._submit_selection_path = MethodType(
+        cutout_main.SelectCutoutSelection._submit_selection_path,
+        operator,
+    )
     result = cutout_main.SelectCutoutSelection.invoke(
         operator, context, SimpleNamespace(value="DOUBLE_CLICK")
     )
@@ -161,8 +187,13 @@ def test_cutout_reuses_image_lasso_gesture_and_double_click_selects_all(monkeypa
     assert issubclass(cutout_main.SelectCutoutSelection, ImageSelectionGesture)
     assert result == {"FINISHED"}
     selection_path = SelectionPath.from_json(window_manager.pie.calls[0][2].selection_path_json)
-    assert selection_path.points == ((0, 0), (320, 0), (320, 180), (0, 180))
-    assert window_manager.pie.calls[0][2].mesh_resolution == 10
+    assert selection_path.points == (
+        (0, 0),
+        (65536, 0),
+        (65536, 32768),
+        (0, 32768),
+    )
+    assert window_manager.pie.calls[0][2].mesh_resolution == 1024
     assert not hasattr(cutout_main, "pending_selection")