From 52d7b47a24bbf4a4bccc016f9936b9ff2bc542f0 Mon Sep 17 00:00:00 2001
From: Robbert van der Helm <mail@robbertvanderhelm.nl>
Date: Fri, 8 Apr 2022 23:10:38 +0200
Subject: [PATCH] Improve block splitting transport information

Don't do any recomputations at the start of the buffer, and also
recompute the bar positions and numbers.
---
 src/wrapper/clap/wrapper.rs | 23 +++++++++++++++++++----
 src/wrapper/vst3/wrapper.rs | 16 ++++++++++++++--
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/wrapper/clap/wrapper.rs b/src/wrapper/clap/wrapper.rs
index 2e10abf9..91742b35 100644
--- a/src/wrapper/clap/wrapper.rs
+++ b/src/wrapper/clap/wrapper.rs
@@ -1349,8 +1349,11 @@ impl<P: ClapPlugin> Wrapper<P> {
                     if context.flags & CLAP_TRANSPORT_HAS_BEATS_TIMELINE != 0 {
                         let beats = context.song_pos_beats as f64 / CLAP_BEATTIME_FACTOR as f64;
 
-                        // This is a bit messy, but we'll try to compensate for the block splitting
+                        // This is a bit messy, but we'll try to compensate for the block splitting.
+                        // We can't use the functions on the transport information object for this
+                        // because we don't have any sample information.
                         if P::SAMPLE_ACCURATE_AUTOMATION
+                            && block_start > 0
                             && (context.flags & CLAP_TRANSPORT_HAS_TEMPO != 0)
                         {
                             transport.pos_beats = Some(
@@ -1367,6 +1370,7 @@ impl<P: ClapPlugin> Wrapper<P> {
 
                         // Same here
                         if P::SAMPLE_ACCURATE_AUTOMATION
+                            && block_start > 0
                             && (context.flags & CLAP_TRANSPORT_HAS_TEMPO != 0)
                         {
                             transport.pos_seconds =
@@ -1376,9 +1380,20 @@ impl<P: ClapPlugin> Wrapper<P> {
                         }
                     }
                     // TODO: CLAP does not mention whether this is behind a flag or not
-                    transport.bar_start_pos_beats =
-                        Some(context.bar_start as f64 / CLAP_BEATTIME_FACTOR as f64);
-                    transport.bar_number = Some(context.bar_number);
+                    if P::SAMPLE_ACCURATE_AUTOMATION && block_start > 0 {
+                        transport.bar_start_pos_beats = match transport.bar_start_pos_beats() {
+                            Some(updated) => Some(updated),
+                            None => Some(context.bar_start as f64 / CLAP_BEATTIME_FACTOR as f64),
+                        };
+                        transport.bar_number = match transport.bar_number() {
+                            Some(updated) => Some(updated),
+                            None => Some(context.bar_number),
+                        };
+                    } else {
+                        transport.bar_start_pos_beats =
+                            Some(context.bar_start as f64 / CLAP_BEATTIME_FACTOR as f64);
+                        transport.bar_number = Some(context.bar_number);
+                    }
                     // TODO: They also aren't very clear about this, but presumably if the loop is
                     //       active and the corresponding song transport information is available then
                     //       this is also available
diff --git a/src/wrapper/vst3/wrapper.rs b/src/wrapper/vst3/wrapper.rs
index 04cab378..d44dedd5 100644
--- a/src/wrapper/vst3/wrapper.rs
+++ b/src/wrapper/vst3/wrapper.rs
@@ -994,7 +994,10 @@ impl<P: Vst3Plugin> IAudioProcessor for Wrapper<P> {
                             Some(context.project_time_samples + block_start as i64);
                         if context.state & (1 << 9) != 0 {
                             // kProjectTimeMusicValid
-                            if P::SAMPLE_ACCURATE_AUTOMATION && (context.state & (1 << 10) != 0) {
+                            if P::SAMPLE_ACCURATE_AUTOMATION
+                                && block_start > 0
+                                && (context.state & (1 << 10) != 0)
+                            {
                                 // kTempoValid
                                 transport.pos_beats = Some(
                                     context.project_time_music
@@ -1008,7 +1011,16 @@ impl<P: Vst3Plugin> IAudioProcessor for Wrapper<P> {
 
                         if context.state & (1 << 11) != 0 {
                             // kBarPositionValid
-                            transport.bar_start_pos_beats = Some(context.bar_position_music);
+                            if P::SAMPLE_ACCURATE_AUTOMATION && block_start > 0 {
+                                // The transport object knows how to recompute this from the other information
+                                transport.bar_start_pos_beats =
+                                    match transport.bar_start_pos_beats() {
+                                        Some(updated) => Some(updated),
+                                        None => Some(context.bar_position_music),
+                                    };
+                            } else {
+                                transport.bar_start_pos_beats = Some(context.bar_position_music);
+                            }
                         }
                         if context.state & (1 << 2) != 0 && context.state & (1 << 12) != 0 {
                             // kCycleActive && kCycleValid