Enhance image editing tests and functionality

- Added parameterized tests for image edit replacement to ensure alpha mode preservation.
- Refactored existing tests to utilize new image editing methods and improve clarity.
- Introduced new tests for image target functionality, ensuring proper handling of shared textures and context.
- Updated various tests to validate alpha mode handling across different scenarios.
- Improved undo/redo functionality in image operators to maintain state consistency.
- Added support for texture node actions, enhancing integration with Blender's node system.
- Ensured that image properties are preserved during operations and that invalid contexts are handled gracefully.

tests/anyimage/common/test_alpha_presentation.py

@@ -24,7 +24,8 @@ def test_owned_color_images_preserve_source_and_use_premul(floating):
     try:
         assert original.alpha_mode == "STRAIGHT"
         np.testing.assert_allclose(images.image_rgba(original), expected)
-        for image in (copied, cropped, edited):
+        assert edited.alpha_mode == original.alpha_mode
+        for image in (copied, cropped):
             assert image.alpha_mode == "PREMUL"
             np.testing.assert_allclose(images.image_rgba(image), expected, atol=1 / 255)
     finally:
@@ -33,13 +34,14 @@ def test_owned_color_images_preserve_source_and_use_premul(floating):
 
 
 @pytest.mark.parametrize("loader", [images.load_image_edit_result, images.load_color_result_image])
-def test_job_color_loader_defaults_to_premul(tmp_path, loader):
+def test_job_loader_uses_edit_or_material_alpha_policy(tmp_path, loader):
     rgba = np.array([[[51, 102, 204, 64]]], dtype=np.uint8)
     Image.fromarray(rgba).save(tmp_path / "image.0001.png")
     original = bpy.data.images.new("Job source", width=1, height=1, alpha=True)
-    result = loader(SimpleNamespace(data=original), tmp_path)
+    source = original if loader == images.load_image_edit_result else SimpleNamespace(data=original)
+    result = loader(source, tmp_path)
     try:
-        assert result.alpha_mode == "PREMUL"
+        assert result.alpha_mode == ("STRAIGHT" if loader == images.load_image_edit_result else "PREMUL")
         assert result.packed_file is not None
         assert original.alpha_mode == "STRAIGHT"
     finally:
@@ -70,6 +72,7 @@ def test_failed_empty_replacement_restores_blending_and_timing():
 
 def test_business_pixels_ignore_premul_read_interpretation():
     original = bpy.data.images.new("Premul read source", width=1, height=1, alpha=True)
+    original.alpha_mode = "PREMUL"
     expected = np.array([0.4, 0.25, 0.1, 0.5], dtype=np.float32)
     result = images.create_image_edit_result(original, expected, (1, 1))
     try:
@@ -87,6 +90,7 @@ def test_business_pixels_ignore_premul_read_interpretation():
 @pytest.mark.parametrize("dirty", [False, True])
 def test_business_read_preserves_shared_packed_source(dirty):
     original = bpy.data.images.new("Read integrity", width=1, height=1, alpha=True)
+    original.alpha_mode = "PREMUL"
     result = images.create_image_edit_result(original, np.array([0.2, 0.4, 0.8, 0.25], dtype=np.float32), (1, 1))
     owner = bpy.data.objects.new("Read owner", None)
     owner.empty_display_type = "IMAGE"
@@ -219,7 +223,7 @@ def test_mask_pack_reopen_add_and_repeat_frame_preserve_hidden_color(tmp_path):
             bpy.data.images.remove(result)
             result = next_result
             result.reload()
-            assert result.alpha_mode == "PREMUL" and result.packed_file is not None
+            assert result.alpha_mode == "STRAIGHT" and result.packed_file is not None
             np.testing.assert_allclose(images.image_rgba(result), rgba, atol=1 / 255)
     finally:
         bpy.data.images.remove(result)