Edit: Fixed toBitSet() ignoring its argument and returning every track in the Edit

BREAKING-CHANGES.md

@@ -2,6 +2,20 @@
 
 ___
 
+### Change
+`toBitSet (const juce::Array<Track*>&)` now returns a bitset of only the tracks passed in.
+
+#### Possible Issues
+Previously it ignored its argument and set a bit for every track in the Edit, so anything built from it addressed the whole Edit. Code that passed a subset of tracks - most visibly `Renderer::Parameters::tracksToDo` and `Renderer::measureStatistics()` - will now render or measure just that subset instead of everything.
+
+#### Workaround
+Pass `getAllTracks (edit)` where the whole Edit really is wanted, or leave `Renderer::Parameters::tracksToDo` empty, which already means "all tracks".
+
+#### Rationale
+The function used its argument only to reach the Edit and then looped over every track, which contradicted its documented behaviour and silently broke subset rendering. See issue #399.
+
+___
+
 ### Change
 `Plugin` has a new pure virtual method `getBusses()` which every subclass must implement.
 

modules/tracktion_core/tracktion_TestConfig.h

@@ -35,6 +35,7 @@
 #define ENGINE_UNIT_TESTS_DAWPROJECT                    1
 #define ENGINE_UNIT_TESTS_DELAY_PLUGIN                  1
 #define ENGINE_UNIT_TESTS_EDIT                          1
+#define ENGINE_UNIT_TESTS_EDIT_UTILITIES                1
 #define ENGINE_UNIT_TESTS_EDITCLIP                      1
 #define ENGINE_UNIT_TESTS_EDIT_LOADER                   1
 #define ENGINE_UNIT_TESTS_EDIT_TIME                     1

modules/tracktion_engine/model/edit/tracktion_EditUtilities.cpp

@@ -255,7 +255,7 @@ juce::BigInteger toBitSet (const juce::Array<Track*>& tracks)
     {
         auto allTracks = getAllTracks (first->edit);
 
-        for (auto t : allTracks)
+        for (auto t : tracks)
             if (int index = allTracks.indexOf (t); index >= 0)
                 bitset.setBit (index);
     }

modules/tracktion_engine/model/edit/tracktion_EditUtilities.h

@@ -95,8 +95,10 @@ bool containsTrack (const Edit&, const Track&);
 /** Returns the TrackOutput if the given track has one. */
 TrackOutput* getTrackOutput (Track&);
 
-/** Returns the set of tracks as a BigInteger with each bit corresponding to the
-    array of all tracks in an Edit. Used in Renderer.
+/** Returns the given tracks as a BigInteger, with each set bit corresponding to a
+    track's index in the Edit's array of all tracks (@see getAllTracks).
+    The Edit is taken from the first track in the array; any tracks not in that Edit
+    are ignored. Used in Renderer.
 */
 juce::BigInteger toBitSet (const juce::Array<Track*>&);
 

modules/tracktion_engine/model/edit/tracktion_EditUtilities.test.cpp

@@ -0,0 +1,100 @@
+/*
+    ,--.                     ,--.     ,--.  ,--.
+  ,-'  '-.,--.--.,--,--.,---.|  |,-.,-'  '-.`--' ,---. ,--,--,      Copyright 2024
+  '-.  .-'|  .--' ,-.  | .--'|     /'-.  .-',--.| .-. ||      \   Tracktion Software
+    |  |  |  |  \ '-'  \ `--.|  \  \  |  |  |  |' '-' '|  ||  |       Corporation
+    `---' `--'   `--`--'`---'`--'`--' `---' `--' `---' `--''--'    www.tracktion.com
+
+    Tracktion Engine uses a GPL/commercial licence - see LICENCE.md for details.
+*/
+
+#if TRACKTION_UNIT_TESTS && ENGINE_UNIT_TESTS_EDIT_UTILITIES
+
+#include <tracktion_engine/../3rd_party/doctest/tracktion_doctest.hpp>
+
+namespace tracktion::inline engine {
+
+//==============================================================================
+//==============================================================================
+TEST_SUITE ("tracktion_engine")
+{
+    TEST_CASE ("toBitSet: returns only the tracks it was given")
+    {
+        auto& engine = *Engine::getEngines()[0];
+        auto edit = Edit::createSingleTrackEdit (engine, Edit::EditRole::forRendering);
+        edit->ensureNumberOfAudioTracks (3);
+
+        auto audioTracks = getAudioTracks (*edit);
+        REQUIRE (audioTracks.size() == 3);
+
+        const auto allTracks = getAllTracks (*edit);
+
+        SUBCASE ("A single track sets a single bit")
+        {
+            const auto bits = toBitSet ({ audioTracks[0] });
+
+            CHECK (bits.countNumberOfSetBits() == 1);
+            CHECK (bits[allTracks.indexOf (audioTracks[0])]);
+            CHECK (! bits[allTracks.indexOf (audioTracks[1])]);
+            CHECK (! bits[allTracks.indexOf (audioTracks[2])]);
+        }
+
+        SUBCASE ("A subset sets exactly those bits")
+        {
+            const auto bits = toBitSet ({ audioTracks[0], audioTracks[2] });
+
+            CHECK (bits.countNumberOfSetBits() == 2);
+            CHECK (bits[allTracks.indexOf (audioTracks[0])]);
+            CHECK (! bits[allTracks.indexOf (audioTracks[1])]);
+            CHECK (bits[allTracks.indexOf (audioTracks[2])]);
+        }
+
+        SUBCASE ("All tracks sets every bit")
+        {
+            const auto bits = toBitSet (allTracks);
+            CHECK (bits.countNumberOfSetBits() == allTracks.size());
+        }
+
+        SUBCASE ("An empty array gives an empty bitset")
+        {
+            CHECK (toBitSet ({}).isZero());
+        }
+
+        SUBCASE ("Tracks from another Edit are ignored")
+        {
+            auto otherEdit = Edit::createSingleTrackEdit (engine, Edit::EditRole::forRendering);
+            auto otherTrack = getAudioTracks (*otherEdit)[0];
+
+            const auto bits = toBitSet ({ audioTracks[1], otherTrack });
+
+            CHECK (bits.countNumberOfSetBits() == 1);
+            CHECK (bits[allTracks.indexOf (audioTracks[1])]);
+        }
+
+        SUBCASE ("Bit indices match Track::getIndexInEditTrackList")
+        {
+            for (auto t : allTracks)
+            {
+                const auto bits = toBitSet ({ t });
+
+                CHECK (bits.countNumberOfSetBits() == 1);
+                CHECK (bits[t->getIndexInEditTrackList()]);
+            }
+        }
+
+        SUBCASE ("toTrackArray round-trips the tracks passed in")
+        {
+            const juce::Array<Track*> subset { audioTracks[2], audioTracks[0] };
+            const auto roundTripped = toTrackArray (*edit, toBitSet (subset));
+
+            CHECK (roundTripped.size() == subset.size());
+
+            for (auto t : subset)
+                CHECK (roundTripped.contains (t));
+        }
+    }
+}
+
+} // namespace tracktion::inline engine
+
+#endif

modules/tracktion_engine/playback/graph/tracktion_EditNodeBuilder.test.cpp

@@ -31,17 +31,6 @@ namespace editnode_test_helpers
         return createNodeForEdit (edit, params);
     }
 
-    static juce::BigInteger getTracksMask (const juce::Array<Track*>& tracks)
-    {
-        juce::BigInteger tracksMask;
-
-        for (auto t : tracks)
-            tracksMask.setBit (t->getIndexInEditTrackList());
-
-        jassert (tracksMask.countNumberOfSetBits() == tracks.size());
-        return tracksMask;
-    }
-
     static Renderer::Statistics logStats (Renderer::Statistics stats)
     {
         MESSAGE (("Stats: peak " + juce::String (stats.peak) + ", avg " + juce::String (stats.average) + ", duration " + juce::String (stats.audioDuration)).toStdString());
@@ -51,15 +40,15 @@ namespace editnode_test_helpers
     static void expectPeak (Edit& edit, TimeRange tr, juce::Array<Track*> tracks, float expectedPeak)
     {
         auto blockSize = edit.engine.getDeviceManager().getBlockSize();
-        auto stats = logStats (Renderer::measureStatistics ("", edit, tr, getTracksMask (tracks), blockSize));
+        auto stats = logStats (Renderer::measureStatistics ("", edit, tr, toBitSet (tracks), blockSize));
         CHECK_MESSAGE (juce::isWithin (stats.peak, expectedPeak, 0.01f),
                        (juce::String ("Expected peak: ") + juce::String (expectedPeak, 4)).toStdString());
     }
 
     static void expectRMS (Edit& edit, TimeRange tr, juce::Array<Track*> tracks, float expectedRMS)
     {
         auto blockSize = edit.engine.getDeviceManager().getBlockSize();
-        auto stats = logStats (Renderer::measureStatistics ("", edit, tr, getTracksMask (tracks), blockSize));
+        auto stats = logStats (Renderer::measureStatistics ("", edit, tr, toBitSet (tracks), blockSize));
         CHECK_MESSAGE (juce::isWithin (stats.average, expectedRMS, 0.01f),
                        (juce::String ("Expected RMS: ") + juce::String (expectedRMS, 4)).toStdString());
     }

modules/tracktion_engine/plugins/tracktion_Plugins.test.cpp

@@ -114,17 +114,6 @@ TEST_SUITE ("tracktion_engine")
     }
 }
 
-static juce::BigInteger getTracksMask (const juce::Array<Track*>& tracks)
-{
-    juce::BigInteger tracksMask;
-
-    for (auto t : tracks)
-        tracksMask.setBit (t->getIndexInEditTrackList());
-
-    jassert (tracksMask.countNumberOfSetBits() == tracks.size());
-    return tracksMask;
-}
-
 template<typename AudioFormatType>
 static std::unique_ptr<juce::TemporaryFile> getSinFile (double sampleRate)
 {
@@ -168,7 +157,7 @@ static std::unique_ptr<juce::TemporaryFile> getSinFile (double sampleRate)
 static void expectPeak (Edit& edit, TimeRange tr, juce::Array<Track*> tracks, float expectedPeak)
 {
     auto blockSize = edit.engine.getDeviceManager().getBlockSize();
-    auto stats = Renderer::measureStatistics ("PDC Tests", edit, tr, getTracksMask (tracks), blockSize);
+    auto stats = Renderer::measureStatistics ("PDC Tests", edit, tr, toBitSet (tracks), blockSize);
     MESSAGE ("Stats: peak " * juce::String (stats.peak).toStdString()
              * ", avg " * juce::String (stats.average).toStdString()
              * ", duration " * juce::String (stats.audioDuration).toStdString());

modules/tracktion_engine/tracktion_engine_model_1.cpp

@@ -37,6 +37,7 @@ using namespace std::literals;
 #include "model/edit/tracktion_Edit.cpp"
 #include "model/edit/tracktion_Edit.test.cpp"
 #include "model/edit/tracktion_EditUtilities.cpp"
+#include "model/edit/tracktion_EditUtilities.test.cpp"
 #include "model/edit/tracktion_Scene.cpp"
 #include "model/edit/tracktion_SourceFileReference.cpp"
 #include "model/edit/tracktion_SourceFileReference.test.cpp"