feat(gui): add GUI components and displays

Source/GUI/WaveformDisplay.cpp

@@ -0,0 +1,45 @@
+#include "WaveformDisplay.h"
+
+namespace serum
+{
+
+void WaveformDisplay::paint (juce::Graphics& g)
+{
+    const auto b = getLocalBounds().toFloat();
+    g.setColour (juce::Colours::black.withAlpha (0.4f));
+    g.fillRoundedRectangle (b, 4.0f);
+    g.setColour (theme::outline);
+    g.drawRoundedRectangle (b.reduced (0.5f), 4.0f, 1.0f);
+
+    const float midY = b.getCentreY();
+    g.setColour (theme::outline);
+    g.drawLine (b.getX() + 4.0f, midY, b.getRight() - 4.0f, midY, 1.0f);
+
+    if (wtLib == nullptr || ! enabled)
+        return;
+
+    const Wavetable& wt = wtLib->getTable (wave);
+    if (! wt.isValid())
+        return;
+
+    const int n = 512;
+    juce::Path path;
+    path.startNewSubPath (b.getX() + 4.0f, midY);
+
+    for (int i = 0; i <= n; ++i)
+    {
+        const float phase = (float) i / (float) n;
+        const float sample = wt.readSafe (wtPos * 255.0f, phase);
+        const float x = b.getX() + 4.0f + ((float) i / (float) n) * (b.getWidth() - 8.0f);
+        const float y = midY - sample * (b.getHeight() * 0.42f);
+        if (i == 0)
+            path.startNewSubPath (x, y);
+        else
+            path.lineTo (x, y);
+    }
+
+    g.setColour (theme::accent);
+    g.strokePath (path, juce::PathStrokeType (1.5f));
+}
+
+} // namespace serum