Cache Vello render output as stitchable textures (#3722)

* WIP render caching

* Hook up render cache to render pipeline

* Fixed offsets

* Initial cleanup

* Integrate cache with context invalidation

* Cleanup

* Improve rounding and reduce tile size to fix vello not rendering

* Include pointer position in cache key

* Avoid unwraps and zero sized textures

* Destroy textures after blitting to surface

* Fix context dependencies

* Exclude footprint from render params

* Batch animation frame messages

* Add vello max render size to preference dialogue

* Remove unused import

* Reorder vello preference

* Clean up preferences dialog

* Apply review suggestions

* Cap max render region size

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

node-graph/libraries/application-io/src/lib.rs

@@ -218,6 +218,7 @@ impl<T: NodeGraphUpdateSender> NodeGraphUpdateSender for std::sync::Mutex<T> {
 
 pub trait GetEditorPreferences {
 	fn use_vello(&self) -> bool;
+	fn max_render_region_area(&self) -> u32;
 }
 
 #[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
@@ -261,6 +262,10 @@ impl GetEditorPreferences for DummyPreferences {
 	fn use_vello(&self) -> bool {
 		false
 	}
+
+	fn max_render_region_area(&self) -> u32 {
+		1024 * 1024
+	}
 }
 
 pub struct EditorApi<Io> {

node-graph/libraries/rendering/src/renderer.rs

@@ -280,6 +280,16 @@ impl RenderMetadata {
 			value.transform = transform * value.transform;
 		}
 	}
+
+	/// Merge another RenderMetadata into this one.
+	/// Values from `other` take precedence for duplicate keys.
+	pub fn merge(&mut self, other: &RenderMetadata) {
+		self.upstream_footprints.extend(other.upstream_footprints.iter().map(|(k, v)| (*k, *v)));
+		self.local_transforms.extend(other.local_transforms.iter().map(|(k, v)| (*k, *v)));
+		self.first_element_source_id.extend(other.first_element_source_id.iter().map(|(k, v)| (*k, *v)));
+		self.click_targets.extend(other.click_targets.iter().map(|(k, v)| (*k, v.clone())));
+		self.clip_targets.extend(other.clip_targets.iter().copied());
+	}
 }
 
 // TODO: Rename to "Graphical"