Restore auto-panning that #2443 had broken (#2562)

* Fix auto panning

* Clean up comments

---------

Co-authored-by: Keavon Chambers <[email protected]>

Author: c-mateo

editor/src/messages/broadcast/broadcast_event.rs

@@ -3,6 +3,7 @@ use crate::messages::prelude::*;
 #[derive(PartialEq, Eq, Clone, Debug, serde::Serialize, serde::Deserialize, Hash)]
 #[impl_message(Message, BroadcastMessage, TriggerEvent)]
 pub enum BroadcastEvent {
+	/// Triggered by requestAnimationFrame in JS
 	AnimationFrame,
 	CanvasTransformed,
 	ToolAbort,

editor/src/messages/input_preprocessor/input_preprocessor_message_handler.rs

@@ -4,6 +4,7 @@ use crate::messages::input_mapper::utility_types::misc::FrameTimeInfo;
 use crate::messages::portfolio::utility_types::KeyboardPlatformLayout;
 use crate::messages::prelude::*;
 use glam::DVec2;
+use std::time::Duration;
 
 pub struct InputPreprocessorMessageData {
 	pub keyboard_platform: KeyboardPlatformLayout,
@@ -97,6 +98,7 @@ impl MessageHandler<InputPreprocessorMessage, InputPreprocessorMessageData> for
 			InputPreprocessorMessage::CurrentTime { timestamp } => {
 				responses.add(AnimationMessage::SetTime(timestamp as f64));
 				self.time = timestamp;
+				self.frame_time.advance_timestamp(Duration::from_millis(timestamp));
 			}
 			InputPreprocessorMessage::WheelScroll { editor_mouse_state, modifier_keys } => {
 				self.update_states_of_modifier_keys(modifier_keys, keyboard_platform, responses);

frontend/wasm/src/editor_api.rs

@@ -152,6 +152,12 @@ impl EditorHandle {
 						for message in editor.handle_message(AnimationMessage::IncrementFrameCounter) {
 							handle.send_frontend_message_to_js(message);
 						}
+
+						// Used by auto-panning, but this could possibly be refactored in the future, see:
+						// <https://github.com/GraphiteEditor/Graphite/pull/2562#discussion_r2041102786>
+						for message in editor.handle_message(BroadcastMessage::TriggerEvent(BroadcastEvent::AnimationFrame)) {
+							handle.send_frontend_message_to_js(message);
+						}
 					});
 				}