Scalable envelope graph

include/ColorHelper.h

@@ -0,0 +1,54 @@
+/* ColorHelper.h - Helper methods for color related algorithms, etc.
+ *
+ * Copyright (c) 2024- Michael Gregorius
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef LMMS_GUI_COLOR_HELPER_H
+#define LMMS_GUI_COLOR_HELPER_H
+
+#include <QColor>
+
+namespace lmms::gui
+{
+
+class ColorHelper
+{
+public:
+	static QColor interpolateInRgb(const QColor& a, const QColor& b, float t)
+	{
+		qreal ar, ag, ab, aa;
+		a.getRgbF(&ar, &ag, &ab, &aa);
+
+		qreal br, bg, bb, ba;
+		b.getRgbF(&br, &bg, &bb, &ba);
+
+		const float interH = lerp(ar, br, t);
+		const float interS = lerp(ag, bg, t);
+		const float interV = lerp(ab, bb, t);
+		const float interA = lerp(aa, ba, t);
+
+		return QColor::fromRgbF(interH, interS, interV, interA);
+	}
+};
+
+} // namespace lmms::gui
+
+#endif // LMMS_GUI_COLOR_HELPER_H

include/EnvelopeGraph.h

@@ -41,22 +41,33 @@ namespace gui
 
 class EnvelopeGraph : public QWidget, public ModelView
 {
+public:
+	enum class ScalingMode
+	{
+		Dynamic,
+		Absolute,
+		Relative
+	};
+
 public:
 	EnvelopeGraph(QWidget* parent);
 
 protected:
 	void modelChanged() override;
 
-	void mousePressEvent(QMouseEvent* me) override;
-	void paintEvent(QPaintEvent* pe) override;
+	void mousePressEvent(QMouseEvent*) override;
+	void contextMenuEvent(QContextMenuEvent*) override;
+	void paintEvent(QPaintEvent*) override;
 
 private:
 	void toggleAmountModel();
 
 private:
 	QPixmap m_envGraph = embed::getIconPixmap("envelope_graph");
 
-	EnvelopeAndLfoParameters* m_params;
+	EnvelopeAndLfoParameters* m_params = nullptr;
+
+	ScalingMode m_scaling = ScalingMode::Dynamic;
 };
 
 } // namespace gui

include/lmms_math.h

@@ -326,6 +326,13 @@ static inline T absMin( T a, T b )
 	return std::abs(a) < std::abs(b) ? a : b;
 }
 
+//! Returns the linear interpolation of the two values
+template<class T, class F>
+constexpr T lerp(T a, T b, F t)
+{
+	return (1. - t) * a + t * b;
+}
+
 // @brief Calculate number of digits which LcdSpinBox would show for a given number
 // @note Once we upgrade to C++20, we could probably use std::formatted_size
 static inline int numDigitsAsInt(float f)