From 418499159b6bd72811ffd3238ad94959dda94c43 Mon Sep 17 00:00:00 2001
From: Andrew Belt <andrewpbelt@gmail.com>
Date: Fri, 11 Jan 2019 04:25:12 -0500
Subject: [PATCH] Add snapping to Knob

---
 include/app/Knob.hpp         |  3 +++
 include/app/ParamWidget.hpp  |  1 -
 include/componentlibrary.hpp |  8 ++------
 src/app/Knob.cpp             | 17 ++++++++++++++---
 4 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/include/app/Knob.hpp b/include/app/Knob.hpp
index 8c48561e..ea14c02d 100644
--- a/include/app/Knob.hpp
+++ b/include/app/Knob.hpp
@@ -12,6 +12,9 @@ struct Knob : ParamWidget {
 	/** Multiplier for mouse movement to adjust knob value */
 	float speed = 1.0;
 	float oldValue = 0.f;
+	/** Enable snapping at integer values */
+	bool snap = false;
+	float snapValue = NAN;
 
 	void onButton(const event::Button &e) override;
 	void onDragStart(const event::DragStart &e) override;
diff --git a/include/app/ParamWidget.hpp b/include/app/ParamWidget.hpp
index f28d24d3..58de6d64 100644
--- a/include/app/ParamWidget.hpp
+++ b/include/app/ParamWidget.hpp
@@ -13,7 +13,6 @@ struct ParamWidget : OpaqueWidget {
 	ParamQuantity *paramQuantity = NULL;
 	float dirtyValue = NAN;
 	Tooltip *tooltip = NULL;
-	bool snap = false;
 
 	~ParamWidget();
 	void step() override;
diff --git a/include/componentlibrary.hpp b/include/componentlibrary.hpp
index a7ccb829..571587ae 100644
--- a/include/componentlibrary.hpp
+++ b/include/componentlibrary.hpp
@@ -59,9 +59,7 @@ struct RoundHugeBlackKnob : RoundKnob {
 
 struct RoundBlackSnapKnob : RoundBlackKnob {
 	RoundBlackSnapKnob() {
-		// TODO
-		// quantity.snap = true;
-		// quantity.smooth = false;
+		snap = true;
 	}
 };
 
@@ -309,9 +307,7 @@ struct BefacoBigKnob : SVGKnob {
 
 struct BefacoBigSnapKnob : BefacoBigKnob {
 	BefacoBigSnapKnob() {
-		// TODO
-		// quantity.snap = true;
-		// quantity.smooth = false;
+		snap = true;
 	}
 };
 
diff --git a/src/app/Knob.cpp b/src/app/Knob.cpp
index e19c0ec5..b47c8226 100644
--- a/src/app/Knob.cpp
+++ b/src/app/Knob.cpp
@@ -20,8 +20,12 @@ void Knob::onButton(const event::Button &e) {
 }
 
 void Knob::onDragStart(const event::DragStart &e) {
-	if (paramQuantity)
+	if (paramQuantity) {
 		oldValue = paramQuantity->getValue();
+		if (snap) {
+			snapValue = oldValue;
+		}
+	}
 
 	app()->window->cursorLock();
 }
@@ -58,8 +62,15 @@ void Knob::onDragMove(const event::DragMove &e) {
 		// Drag slower if Mod is held
 		if (app()->window->isModPressed())
 			delta /= 16.f;
-		float oldValue = paramQuantity->getSmoothValue();
-		paramQuantity->setSmoothValue(oldValue + delta);
+
+		if (snap) {
+			snapValue += delta;
+			snapValue = math::clamp(snapValue, paramQuantity->getMinValue(), paramQuantity->getMaxValue());
+			paramQuantity->setValue(std::round(snapValue));
+		}
+		else {
+			paramQuantity->setSmoothValue(paramQuantity->getSmoothValue() + delta);
+		}
 	}
 
 	ParamWidget::onDragMove(e);