Return early in InProgresStroke.UpdateShape when no update needed

PiperOrigin-RevId: 874385172

Author: sfreilich

ink/strokes/in_progress_stroke.cc

@@ -115,6 +115,14 @@ absl::Status InProgressStroke::EnqueueInputs(
   return absl::OkStatus();
 }
 
+bool InProgressStroke::HasQueuedInputs() const {
+  return !queued_real_inputs_.IsEmpty() ||
+         !queued_predicted_inputs_.IsEmpty() ||
+         // The only thing queued was empty, but a previous prediction was
+         // cleared as a result.
+         (queued_inputs_since_last_update_shape_ && PredictedInputCount() > 0);
+}
+
 absl::Status InProgressStroke::UpdateShape(Duration32 current_elapsed_time) {
   if (!brush_.has_value()) {
     return absl::FailedPreconditionError(
@@ -126,11 +134,14 @@ absl::Status InProgressStroke::UpdateShape(Duration32 current_elapsed_time) {
       !status.ok()) {
     return status;
   }
-  if (inputs_are_finished_ || !queued_real_inputs_.IsEmpty() ||
-      !queued_predicted_inputs_.IsEmpty() ||
-      (queued_inputs_since_last_update_shape_ && PredictedInputCount() > 0)) {
+  current_elapsed_time_ = current_elapsed_time;
+
+  if (HasQueuedInputs()) {
     // Erase any old predicted inputs.
     processed_inputs_.Erase(real_input_count_);
+  } else if (!ChangesWithTime()) {
+    // Exit early if no change is needed.
+    return absl::OkStatus();
   }
 
   if (absl::Status status = processed_inputs_.Append(queued_real_inputs_);
@@ -152,8 +163,6 @@ absl::Status InProgressStroke::UpdateShape(Duration32 current_elapsed_time) {
     return status;
   }
 
-  current_elapsed_time_ = current_elapsed_time;
-
   input_modeler_.ExtendStroke(queued_real_inputs_, queued_predicted_inputs_,
                               current_elapsed_time);
   uint32_t num_coats = BrushCoatCount();
@@ -172,12 +181,7 @@ absl::Status InProgressStroke::UpdateShape(Duration32 current_elapsed_time) {
 }
 
 bool InProgressStroke::NeedsUpdate() const {
-  if (!queued_real_inputs_.IsEmpty() || !queued_predicted_inputs_.IsEmpty() ||
-      // There are processed predicted inputs to be cleared.
-      (queued_inputs_since_last_update_shape_ && PredictedInputCount() > 0)) {
-    return true;
-  }
-  return ChangesWithTime();
+  return HasQueuedInputs() || ChangesWithTime();
 }
 
 bool InProgressStroke::ChangesWithTime() const {

ink/strokes/in_progress_stroke.h

@@ -271,6 +271,10 @@ class InProgressStroke {
 
   absl::Status ValidateNewElapsedTime(Duration32 current_elapsed_time) const;
 
+  // Whether `UpdateShape` might be needed due to a prior call to
+  // `EnqueueInputs`.
+  bool HasQueuedInputs() const;
+
   std::optional<Brush> brush_;
   // Real and predicted inputs that have been queued by calls to
   // `EnqueueInputs()` since the last call to `UpdateShape()`.