plugin: limit number of undo states that get added

- makes message thread poll for undo state
- ensures that any undo state added is different (prevents jsfx just spamming undo points without making a change to serialized state)
- currently, this mode is enabled explicitly in the preferences (off by default)

plugin/editor.cpp

@@ -47,6 +47,7 @@ struct YsfxEditor::Impl {
     std::unique_ptr<juce::AlertWindow> m_modalAlert;
     std::unique_ptr<juce::Timer> m_infoTimer;
     std::unique_ptr<juce::Timer> m_relayoutTimer;
+    std::unique_ptr<juce::Timer> m_undoTimer;
     std::unique_ptr<juce::FileChooser> m_fileChooser;
     std::unique_ptr<juce::PopupMenu> m_recentFilesPopup;
     std::unique_ptr<juce::PopupMenu> m_recentFilesOptsPopup;
@@ -57,6 +58,7 @@ struct YsfxEditor::Impl {
     bool m_fileChooserActive = false;
     bool m_mustResizeToGfx = true;
     bool m_maintainState = false;
+    int m_keepUndoState{1};
     float m_currentScaling{1.0f};
     uint64_t m_sliderVisible[ysfx_max_slider_groups]{0};
     bool m_visibleSlidersChanged{false};
@@ -900,6 +902,22 @@ void YsfxEditor::Impl::initializeProperties()
     #endif
 
     m_pluginProperties.reset(new juce::PropertiesFile{options});
+
+    // Manual undo stack
+    // 1 - default (off in current release, on in the future)
+    // 2 - enabled
+    // 3 - always disabled
+    {
+        juce::ScopedLock lock{m_pluginProperties->getLock()};
+
+        auto key = juce::String("ysfx_maintain_serialization_undo");
+        if (m_pluginProperties->containsKey(key)) {
+            m_keepUndoState = m_pluginProperties->getIntValue(key);
+        } else {
+            m_pluginProperties->setValue(key, 1);
+            m_pluginProperties->setNeedsToBeSaved(true);
+        }
+    }
 }
 
 void YsfxEditor::Impl::createUI()
@@ -1014,6 +1032,15 @@ void YsfxEditor::Impl::connectUI()
 
     m_infoTimer.reset(FunctionalTimer::create([this]() { grabInfoAndUpdate(); }));
     m_infoTimer->startTimer(100);
+
+    m_undoTimer.reset(
+        FunctionalTimer::create(
+            [this]() {
+                if (m_keepUndoState == 2) m_proc->checkForUndoableChanges();
+            }
+        )
+    );
+    m_undoTimer->startTimer(500);
 }
 
 void YsfxEditor::Impl::relayoutUI()

plugin/processor.cpp

@@ -42,6 +42,7 @@ struct YsfxProcessor::Impl : public juce::AudioProcessorListener {
     YsfxCurrentPresetInfo::Ptr m_currentPresetInfo{new YsfxCurrentPresetInfo};
     ysfx_bank_shared m_bank{nullptr};
 
+    int m_maxUndoStack{64};
     double m_sample_rate{44100.0};
     uint32_t m_block_size{256};
 
@@ -334,6 +335,14 @@ void YsfxProcessor::loadJsfxPreset(YsfxInfo::Ptr info, ysfx_bank_shared bank, ui
     }
 }
 
+void YsfxProcessor::checkForUndoableChanges()
+{
+    if (ysfx_fetch_want_undopoint(m_impl->m_fx.get())) {
+        m_impl->m_wantUndoPoint = true;
+        m_impl->m_background->wakeUp();
+    }
+}
+
 void YsfxProcessor::popUndoState()
 {
     m_impl->m_undoRequest = UndoRequest::wantUndo;
@@ -794,11 +803,6 @@ void YsfxProcessor::Impl::processSliderChanges()
         notify = automated ? true : notify;
     };
 
-    m_wantUndoPoint = m_wantUndoPoint | ysfx_fetch_want_undopoint(fx);
-    if (m_wantUndoPoint) {
-        notify = true;
-    };
-
     // this will sync parameters later (on message thread)
     if (notify) m_background->wakeUp();
 
@@ -988,15 +992,17 @@ void YsfxProcessor::Impl::installNewFx(YsfxInfo::Ptr info, ysfx_bank_shared bank
     m_updateParamNames = true;
     m_wantUndoPoint = false;
 
+    if (m_info->m_name != info->m_name) {
+        m_undoStack.clear();
+        m_hasUndo = false;
+        m_hasRedo = false;
+    }
+
     YsfxCurrentPresetInfo::Ptr presetInfo{new YsfxCurrentPresetInfo()};
     std::atomic_store(&m_currentPresetInfo, presetInfo);
     std::atomic_store(&m_bank, bank);
     std::atomic_store(&m_info, info);
 
-    m_undoStack.clear();
-    m_hasUndo = false;
-    m_hasRedo = false;
-
     m_background->wakeUp();
 }
 
@@ -1032,6 +1038,8 @@ void YsfxProcessor::Impl::loadNewPreset(const ysfx_preset_t &preset)
 
 void YsfxProcessor::Impl::pushUndoState()
 {
+    if (!m_currentPresetInfo) return;
+
     ysfx_state_t* state;
     {
         AudioProcessorSuspender sus(*m_self);
@@ -1040,7 +1048,12 @@ void YsfxProcessor::Impl::pushUndoState()
         state = ysfx_save_state(fx);
     }
 
-    if (!m_currentPresetInfo) return;
+    // Verify that we don't already have this exact state
+    if ((m_undoPosition < m_undoStack.size()) && (m_undoPosition >= 0) && ysfx_is_state_equal(state, m_undoStack[m_undoPosition]->state)) {
+        ysfx_state_free(state);
+        return;
+    }
+
     ysfx_preset_u preset;
     preset.reset(ysfx_preset_from_state(m_currentPresetInfo->m_lastChosenPreset.toStdString().c_str(), state));
 
@@ -1051,7 +1064,7 @@ void YsfxProcessor::Impl::pushUndoState()
     m_undoStack.emplace_back(std::move(preset));
     m_undoPosition = static_cast<int>(m_undoStack.size()) - 1;
 
-    if (m_undoStack.size() > 14) {
+    if (m_undoStack.size() > m_maxUndoStack) {
         m_undoStack.pop_front();
         m_undoPosition -= 1;
     }

plugin/processor.h

@@ -36,6 +36,7 @@ class YsfxProcessor : public juce::AudioProcessor {
     void loadJsfxFile(const juce::String &filePath, ysfx_state_t *initialState, bool async, bool preserveState);
     void loadJsfxPreset(YsfxInfo::Ptr info, ysfx_bank_shared bank, uint32_t index, PresetLoadMode load, bool async);
     void popUndoState();
+    void checkForUndoableChanges();
     void redoState();
     bool canUndo();
     bool canRedo();