From 2b27a7ab1e80e91a23d7ca981e23ffa3ecd17f30 Mon Sep 17 00:00:00 2001
From: Damien Zammit <damien@zamaudio.com>
Date: Sun, 1 May 2016 18:04:38 +1000
Subject: [PATCH] Add ability to set scrolling step on knobs, does not apply to
 drag

- Fine tuning with CTRL-scroll is 1/10 of the scroll step set
- Set the major scroll step with setScrollStep(<float>)

Signed-off-by: Damien Zammit <damien@zamaudio.com>
---
 dgl/ImageWidgets.hpp     |  2 ++
 dgl/src/ImageWidgets.cpp | 21 +++++++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/dgl/ImageWidgets.hpp b/dgl/ImageWidgets.hpp
index aafe1962..3bad8a84 100644
--- a/dgl/ImageWidgets.hpp
+++ b/dgl/ImageWidgets.hpp
@@ -112,6 +112,7 @@ public:
     void setDefault(float def) noexcept;
     void setRange(float min, float max) noexcept;
     void setStep(float step) noexcept;
+    void setScrollStep(float step) noexcept;
     void setValue(float value, bool sendCallback = false) noexcept;
     void setUsingLogScale(bool yesNo) noexcept;
 
@@ -131,6 +132,7 @@ private:
     Image fImage;
     float fMinimum;
     float fMaximum;
+    float fScrollStep;
     float fStep;
     float fValue;
     float fValueDef;
diff --git a/dgl/src/ImageWidgets.cpp b/dgl/src/ImageWidgets.cpp
index 9b4625c1..c77bf65a 100644
--- a/dgl/src/ImageWidgets.cpp
+++ b/dgl/src/ImageWidgets.cpp
@@ -195,6 +195,7 @@ ImageKnob::ImageKnob(Window& parent, const Image& image, Orientation orientation
       fImage(image),
       fMinimum(0.0f),
       fMaximum(1.0f),
+      fScrollStep(0.0f),
       fStep(0.0f),
       fValue(0.5f),
       fValueDef(fValue),
@@ -223,6 +224,7 @@ ImageKnob::ImageKnob(Widget* widget, const Image& image, Orientation orientation
       fImage(image),
       fMinimum(0.0f),
       fMaximum(1.0f),
+      fScrollStep(0.0f),
       fStep(0.0f),
       fValue(0.5f),
       fValueDef(fValue),
@@ -251,6 +253,7 @@ ImageKnob::ImageKnob(const ImageKnob& imageKnob)
       fImage(imageKnob.fImage),
       fMinimum(imageKnob.fMinimum),
       fMaximum(imageKnob.fMaximum),
+      fScrollStep(imageKnob.fScrollStep),
       fStep(imageKnob.fStep),
       fValue(imageKnob.fValue),
       fValueDef(imageKnob.fValueDef),
@@ -279,6 +282,7 @@ ImageKnob& ImageKnob::operator=(const ImageKnob& imageKnob)
     fImage    = imageKnob.fImage;
     fMinimum  = imageKnob.fMinimum;
     fMaximum  = imageKnob.fMaximum;
+    fScrollStep = imageKnob.fScrollStep;
     fStep     = imageKnob.fStep;
     fValue    = imageKnob.fValue;
     fValueDef = imageKnob.fValueDef;
@@ -363,6 +367,11 @@ void ImageKnob::setRange(float min, float max) noexcept
     fMaximum = max;
 }
 
+void ImageKnob::setScrollStep(float step) noexcept
+{
+    fScrollStep = step;
+}
+
 void ImageKnob::setStep(float step) noexcept
 {
     fStep = step;
@@ -599,8 +608,16 @@ bool ImageKnob::onScroll(const ScrollEvent& ev)
     if (! contains(ev.pos))
         return false;
 
-    const float d     = (ev.mod & kModifierControl) ? 2000.0f : 200.0f;
-    float       value = (fUsingLog ? _invlogscale(fValueTmp) : fValueTmp) + (float(fMaximum - fMinimum) / d * 10.f * ev.delta.getY());
+    float value, d;
+
+    if (d_isZero(fScrollStep)) {
+        d = (ev.mod & kModifierControl) ? 2000.0f : 200.0f;
+        value = (fUsingLog ? _invlogscale(fValueTmp) : fValueTmp) + (float(fMaximum - fMinimum) / d * 10.f * ev.delta.getY());
+    } else {
+        d = (ev.mod & kModifierControl) ? fScrollStep * 0.1f : fScrollStep;
+        value = (fUsingLog ? _invlogscale(fValueTmp + d * ev.delta.getY())
+                           : fValueTmp + d * ev.delta.getY());
+    }
 
     if (fUsingLog)
         value = _logscale(value);