Initial commit: InstaLPEQ linear phase EQ plugin

Full-featured linear phase EQ with interactive graphical curve display.
FIR-based processing (8192-tap), 8 parametric bands, multi-platform
CI/CD (Windows/macOS/Linux), InstaDrums visual style.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Source/NodeParameterPanel.cpp

@@ -0,0 +1,145 @@
+#include "NodeParameterPanel.h"
+#include "LookAndFeel.h"
+
+NodeParameterPanel::NodeParameterPanel()
+{
+    setupSlider (freqSlider, freqLabel, 20.0, 20000.0, 1.0, " Hz");
+    freqSlider.setSkewFactorFromMidPoint (1000.0);
+
+    setupSlider (gainSlider, gainLabel, -24.0, 24.0, 0.1, " dB");
+
+    setupSlider (qSlider, qLabel, 0.1, 18.0, 0.01, "");
+    qSlider.setSkewFactorFromMidPoint (1.0);
+    qSlider.getProperties().set (InstaLPEQLookAndFeel::knobTypeProperty, "dark");
+
+    typeSelector.addItem ("Peak", 1);
+    typeSelector.addItem ("Low Shelf", 2);
+    typeSelector.addItem ("High Shelf", 3);
+    typeSelector.setSelectedId (1, juce::dontSendNotification);
+    typeSelector.addListener (this);
+    addAndMakeVisible (typeSelector);
+
+    deleteButton.addListener (this);
+    addAndMakeVisible (deleteButton);
+
+    addAndMakeVisible (bandInfoLabel);
+    bandInfoLabel.setJustificationType (juce::Justification::centredLeft);
+
+    setSelectedBand (-1, nullptr);
+}
+
+void NodeParameterPanel::setupSlider (juce::Slider& s, juce::Label& l, double min, double max, double step, const char* suffix)
+{
+    s.setSliderStyle (juce::Slider::RotaryHorizontalVerticalDrag);
+    s.setTextBoxStyle (juce::Slider::TextBoxBelow, false, 60, 16);
+    s.setRange (min, max, step);
+    s.setTextValueSuffix (suffix);
+    s.addListener (this);
+    addAndMakeVisible (s);
+
+    l.setJustificationType (juce::Justification::centred);
+    addAndMakeVisible (l);
+}
+
+void NodeParameterPanel::setSelectedBand (int index, const EQBand* band)
+{
+    selectedIndex = index;
+    updatingFromExternal = true;
+
+    bool hasBand = (index >= 0 && band != nullptr);
+    freqSlider.setEnabled (hasBand);
+    gainSlider.setEnabled (hasBand);
+    qSlider.setEnabled (hasBand);
+    typeSelector.setEnabled (hasBand);
+    deleteButton.setEnabled (hasBand);
+
+    if (hasBand)
+    {
+        currentBand = *band;
+        freqSlider.setValue (band->frequency, juce::dontSendNotification);
+        gainSlider.setValue (band->gainDb, juce::dontSendNotification);
+        qSlider.setValue (band->q, juce::dontSendNotification);
+        typeSelector.setSelectedId ((int) band->type + 1, juce::dontSendNotification);
+        bandInfoLabel.setText ("Band " + juce::String (index + 1), juce::dontSendNotification);
+    }
+    else
+    {
+        bandInfoLabel.setText ("No band selected", juce::dontSendNotification);
+    }
+
+    updatingFromExternal = false;
+    repaint();
+}
+
+void NodeParameterPanel::paint (juce::Graphics& g)
+{
+    auto bounds = getLocalBounds().toFloat();
+    g.setColour (InstaLPEQLookAndFeel::bgMedium.darker (0.2f));
+    g.fillRoundedRectangle (bounds, 4.0f);
+    g.setColour (InstaLPEQLookAndFeel::bgLight.withAlpha (0.3f));
+    g.drawRoundedRectangle (bounds, 4.0f, 1.0f);
+}
+
+void NodeParameterPanel::resized()
+{
+    auto bounds = getLocalBounds().reduced (6);
+    float scale = (float) getHeight() / 90.0f;
+
+    auto left = bounds.removeFromLeft (100);
+    bandInfoLabel.setBounds (left.removeFromTop ((int) (20 * scale)));
+
+    auto typeBounds = left.removeFromTop ((int) (22 * scale));
+    typeSelector.setBounds (typeBounds.reduced (2));
+
+    auto delBounds = left.removeFromTop ((int) (22 * scale));
+    deleteButton.setBounds (delBounds.reduced (2));
+
+    // Knobs take the rest
+    int knobW = bounds.getWidth() / 3;
+    int labelH = (int) std::max (14.0f, 16.0f * scale);
+
+    auto freqArea = bounds.removeFromLeft (knobW);
+    freqLabel.setBounds (freqArea.removeFromTop (labelH));
+    freqSlider.setBounds (freqArea);
+
+    auto gainArea = bounds.removeFromLeft (knobW);
+    gainLabel.setBounds (gainArea.removeFromTop (labelH));
+    gainSlider.setBounds (gainArea);
+
+    auto qArea = bounds;
+    qLabel.setBounds (qArea.removeFromTop (labelH));
+    qSlider.setBounds (qArea);
+}
+
+void NodeParameterPanel::sliderValueChanged (juce::Slider* slider)
+{
+    if (updatingFromExternal || selectedIndex < 0 || listener == nullptr)
+        return;
+
+    if (slider == &freqSlider)
+        currentBand.frequency = (float) freqSlider.getValue();
+    else if (slider == &gainSlider)
+        currentBand.gainDb = (float) gainSlider.getValue();
+    else if (slider == &qSlider)
+        currentBand.q = (float) qSlider.getValue();
+
+    listener->nodeParameterChanged (selectedIndex, currentBand);
+}
+
+void NodeParameterPanel::comboBoxChanged (juce::ComboBox* box)
+{
+    if (updatingFromExternal || selectedIndex < 0 || listener == nullptr)
+        return;
+
+    if (box == &typeSelector)
+    {
+        currentBand.type = static_cast<EQBand::Type> (typeSelector.getSelectedId() - 1);
+        listener->nodeParameterChanged (selectedIndex, currentBand);
+    }
+}
+
+void NodeParameterPanel::buttonClicked (juce::Button* button)
+{
+    if (button == &deleteButton && selectedIndex >= 0 && listener != nullptr)
+        listener->nodeDeleteRequested (selectedIndex);
+}