v1.2.2: Live spectrum analyzer, makeup gain, drag-and-drop signal chain

- Real-time FFT spectrum analyzer drawn behind EQ curves
- Makeup gain knob (+/- 24 dB) after limiter
- Draggable signal chain panel: reorder Master Gain / Limiter / Makeup Gain
- Chain order saved/restored with DAW session
- Scaled fonts in signal chain panel

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

Source/SignalChainPanel.cpp

@@ -0,0 +1,165 @@
+#include "SignalChainPanel.h"
+#include "LookAndFeel.h"
+
+SignalChainPanel::SignalChainPanel()
+{
+    setMouseCursor (juce::MouseCursor::DraggingHandCursor);
+}
+
+void SignalChainPanel::setOrder (const std::array<InstaLPEQProcessor::ChainStage, numBlocks>& order)
+{
+    if (currentOrder != order)
+    {
+        currentOrder = order;
+        repaint();
+    }
+}
+
+juce::String SignalChainPanel::getStageName (InstaLPEQProcessor::ChainStage stage) const
+{
+    switch (stage)
+    {
+        case InstaLPEQProcessor::MasterGain: return "MASTER GAIN";
+        case InstaLPEQProcessor::Limiter:    return "LIMITER";
+        case InstaLPEQProcessor::MakeupGain: return "MAKEUP GAIN";
+        default: return "?";
+    }
+}
+
+juce::Colour SignalChainPanel::getStageColour (InstaLPEQProcessor::ChainStage stage) const
+{
+    switch (stage)
+    {
+        case InstaLPEQProcessor::MasterGain: return juce::Colour (0xffff8833);
+        case InstaLPEQProcessor::Limiter:    return juce::Colour (0xffff4455);
+        case InstaLPEQProcessor::MakeupGain: return juce::Colour (0xff44bbff);
+        default: return InstaLPEQLookAndFeel::textSecondary;
+    }
+}
+
+juce::Rectangle<float> SignalChainPanel::getBlockRect (int index) const
+{
+    auto bounds = getLocalBounds().toFloat().reduced (2);
+    float gap = 6.0f;
+    float blockW = (bounds.getWidth() - gap * (numBlocks - 1)) / numBlocks;
+    float x = bounds.getX() + index * (blockW + gap);
+    return { x, bounds.getY(), blockW, bounds.getHeight() };
+}
+
+int SignalChainPanel::getBlockAtX (float x) const
+{
+    for (int i = 0; i < numBlocks; ++i)
+    {
+        if (getBlockRect (i).contains (x, getHeight() * 0.5f))
+            return i;
+    }
+    return -1;
+}
+
+void SignalChainPanel::paint (juce::Graphics& g)
+{
+    auto bounds = getLocalBounds().toFloat();
+
+    // Background
+    g.setColour (InstaLPEQLookAndFeel::bgDark.darker (0.3f));
+    g.fillRoundedRectangle (bounds, 4.0f);
+    g.setColour (InstaLPEQLookAndFeel::bgLight.withAlpha (0.2f));
+    g.drawRoundedRectangle (bounds, 4.0f, 1.0f);
+
+    auto* lf = dynamic_cast<InstaLPEQLookAndFeel*> (&getLookAndFeel());
+
+    // Draw arrows between blocks (scale with height)
+    float arrowScale = bounds.getHeight() / 30.0f;
+    for (int i = 0; i < numBlocks - 1; ++i)
+    {
+        auto r1 = getBlockRect (i);
+        auto r2 = getBlockRect (i + 1);
+        float arrowX = (r1.getRight() + r2.getX()) * 0.5f;
+        float arrowY = bounds.getCentreY();
+        float aw = 5.0f * arrowScale;
+        float ah = 6.0f * arrowScale;
+        g.setColour (InstaLPEQLookAndFeel::textSecondary.withAlpha (0.5f));
+
+        juce::Path arrow;
+        arrow.addTriangle (arrowX - aw, arrowY - ah, arrowX - aw, arrowY + ah, arrowX + aw, arrowY);
+        g.fillPath (arrow);
+    }
+
+    // Draw blocks
+    for (int i = 0; i < numBlocks; ++i)
+    {
+        bool isDragged = (i == draggedIndex);
+        auto rect = getBlockRect (i);
+
+        // If this block is being dragged, offset it
+        if (isDragged)
+        {
+            float offset = dragCurrentX - dragOffsetX;
+            rect = rect.withX (rect.getX() + offset);
+        }
+
+        auto colour = getStageColour (currentOrder[i]);
+
+        // Block background
+        g.setColour (isDragged ? colour.withAlpha (0.25f) : colour.withAlpha (0.12f));
+        g.fillRoundedRectangle (rect, 4.0f);
+
+        // Block border
+        g.setColour (isDragged ? colour.withAlpha (0.8f) : colour.withAlpha (0.4f));
+        g.drawRoundedRectangle (rect, 4.0f, isDragged ? 2.0f : 1.0f);
+
+        // Label — scale with block height
+        juce::Font font = lf ? lf->getBoldFont (std::max (12.0f, rect.getHeight() * 0.45f))
+                              : juce::Font (juce::FontOptions (14.0f));
+        g.setFont (font);
+        g.setColour (isDragged ? colour : colour.withAlpha (0.8f));
+        g.drawText (getStageName (currentOrder[i]), rect.reduced (4), juce::Justification::centred, false);
+    }
+
+    // "SIGNAL CHAIN" label on the left
+    if (lf)
+    {
+        g.setFont (lf->getRegularFont (10.0f));
+        g.setColour (InstaLPEQLookAndFeel::textSecondary.withAlpha (0.5f));
+    }
+}
+
+void SignalChainPanel::resized() {}
+
+void SignalChainPanel::mouseDown (const juce::MouseEvent& e)
+{
+    draggedIndex = getBlockAtX (e.position.x);
+    if (draggedIndex >= 0)
+    {
+        dragOffsetX = e.position.x;
+        dragCurrentX = e.position.x;
+    }
+}
+
+void SignalChainPanel::mouseDrag (const juce::MouseEvent& e)
+{
+    if (draggedIndex < 0)
+        return;
+
+    dragCurrentX = e.position.x;
+
+    // Check if we should swap with a neighbor
+    int targetIndex = getBlockAtX (e.position.x);
+    if (targetIndex >= 0 && targetIndex != draggedIndex)
+    {
+        std::swap (currentOrder[draggedIndex], currentOrder[targetIndex]);
+        draggedIndex = targetIndex;
+        dragOffsetX = e.position.x;
+
+        if (listener)
+            listener->chainOrderChanged (currentOrder);
+    }
+
+    repaint();
+}
+
+void SignalChainPanel::mouseUp (const juce::MouseEvent&)
+{
+    draggedIndex = -1;
+    repaint();
+}