Introduce API for setting view defaults from python (rerun-io#6545)

### What
- Resolves: rerun-io#6539
- Builds on top of: rerun-io#6543
(no-merge until that lands)

Just a bit of plumbing to write all the provided defaults to the correct
location in the blueprint.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6545?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/6545?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/6545)
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

To run all checks from `main`, comment on the PR with `@rerun-bot
full-check`.

crates/re_types_builder/src/codegen/python/views.rs

@@ -18,7 +18,7 @@ from .. import archetypes as blueprint_archetypes
 from .. import components as blueprint_components
 from ... import datatypes
 from ... import components
-from ..._baseclasses import AsComponents
+from ..._baseclasses import AsComponents, ComponentBatchLike
 from ...datatypes import EntityPathLike, Utf8Like
 from ..api import SpaceView, SpaceViewContentsLike
 ",
@@ -41,6 +41,7 @@ fn init_method(reporter: &Reporter, objects: &Objects, obj: &Object) -> String {
     contents: SpaceViewContentsLike = "$origin/**",
     name: Utf8Like | None = None,
     visible: blueprint_components.VisibleLike | None = None,
+    defaults: list[Union[AsComponents, ComponentBatchLike]] = [],
     "#
     .to_owned();
 
@@ -109,6 +110,12 @@ See [rerun.blueprint.archetypes.SpaceViewContents][]."
 Defaults to true if not specified."
                 .to_owned(),
         ),
+        (
+            "defaults",
+            "List of default components or component batches to add to the space view. When an archetype
+in the view is missing a component included in this set, the value of default will be used
+instead of the normal fallback for the visualizer.".to_owned(),
+        )
     ];
     for field in &obj.fields {
         let doc_content = field.docs.doc_lines_for_untagged_and("py");
@@ -174,7 +181,7 @@ Defaults to true if not specified."
     }
     code.push_indented(
         1,
-        &format!(r#"super().__init__(class_identifier="{identifier}", origin=origin, contents=contents, name=name, visible=visible, properties=properties)"#),
+        &format!(r#"super().__init__(class_identifier="{identifier}", origin=origin, contents=contents, name=name, visible=visible, properties=properties, defaults=defaults)"#),
         1,
     );
 

examples/python/blueprint/blueprint.py

@@ -29,7 +29,9 @@ def main() -> None:
         blueprint = Blueprint(
             Grid(
                 Spatial2DView(name="Rect 0", origin="/", contents=["image", "rect/0"]),
-                Spatial2DView(name="Rect 1", origin="/", contents=["image", "rect/1"]),
+                Spatial2DView(
+                    name="Rect 1", origin="/", contents=["image", "rect/1"], defaults=[rr.components.Radius(2)]
+                ),
             ),
             BlueprintPanel(state="collapsed"),
             SelectionPanel(state="collapsed"),

rerun_py/rerun_sdk/rerun/blueprint/api.py

@@ -5,7 +5,7 @@
 
 import rerun_bindings as bindings
 
-from .._baseclasses import AsComponents
+from .._baseclasses import AsComponents, ComponentBatchLike
 from .._spawn import _spawn_viewer
 from ..datatypes import EntityPathLike, Utf8ArrayLike, Utf8Like
 from ..memory import MemoryRecording
@@ -44,6 +44,7 @@ def __init__(
         name: Utf8Like | None,
         visible: VisibleLike | None = None,
         properties: dict[str, AsComponents] = {},
+        defaults: list[Union[AsComponents, ComponentBatchLike]] = [],
     ):
         """
         Construct a blueprint for a new space view.
@@ -67,6 +68,10 @@ def __init__(
             Defaults to true if not specified.
         properties
             Dictionary of property archetypes to add to space view's internal hierarchy.
+        defaults:
+            List of default components or component batches to add to the space view. When an archetype
+            in the view is missing a component included in this set, the value of default will be used
+            instead of the normal fallback for the visualizer.
 
         """
         self.id = uuid.uuid4()
@@ -76,6 +81,7 @@ def __init__(
         self.contents = contents
         self.visible = visible
         self.properties = properties
+        self.defaults = defaults
 
     def blueprint_path(self) -> str:
         """
@@ -119,6 +125,14 @@ def _log_to_stream(self, stream: RecordingStream) -> None:
         for prop_name, prop in self.properties.items():
             stream.log(f"{self.blueprint_path()}/{prop_name}", prop, recording=stream)  # type: ignore[attr-defined]
 
+        for default in self.defaults:
+            if hasattr(default, "as_component_batches"):
+                stream.log(f"{self.blueprint_path()}/defaults", default, recording=stream)  # type: ignore[attr-defined]
+            elif hasattr(default, "component_name"):
+                stream.log(f"{self.blueprint_path()}/defaults", [default], recording=stream)  # type: ignore[attr-defined]
+            else:
+                raise ValueError(f"Provided default: {default} is neither a component nor a component batch.")
+
     def _repr_html_(self) -> Any:
         """IPython interface to conversion to html."""
         return as_html(blueprint=self)