From 16624f31391bae51db770a9e9bd8899e7746b068 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 20 Jun 2017 23:41:05 +0200
Subject: Add API to compute parameter delta, depending on AutomationType

---
 libs/ardour/parameter_descriptor.cc | 39 +++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

(limited to 'libs/ardour/parameter_descriptor.cc')

diff --git a/libs/ardour/parameter_descriptor.cc b/libs/ardour/parameter_descriptor.cc
index 7ed0c78512..a63c90d1db 100644
--- a/libs/ardour/parameter_descriptor.cc
+++ b/libs/ardour/parameter_descriptor.cc
@@ -354,4 +354,43 @@ ParameterDescriptor::from_interface (float val) const
 	return val;
 }
 
+bool
+ParameterDescriptor::is_linear () const
+{
+	if (logarithmic) {
+		return false;
+	}
+	switch(type) {
+		case GainAutomation:
+		case EnvelopeAutomation:
+		case BusSendLevel:
+			return false;
+		default:
+			break;
+	}
+	return true;
+}
+
+float
+ParameterDescriptor::compute_delta (float from, float to) const
+{
+	if (is_linear ()) {
+		return to - from;
+	}
+	if (from == 0) {
+		return 0;
+	}
+	return to / from;
+}
+
+float
+ParameterDescriptor::apply_delta (float val, float delta) const
+{
+	if (is_linear ()) {
+		return val + delta;
+	} else {
+		return val * delta;
+	}
+}
+
 } // namespace ARDOUR
-- 
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