From d29b51dfd99eaec28bdc86486e21b6fc1a8ae2f9 Mon Sep 17 00:00:00 2001
From: Mirek Fidler <mirek.fidler@gmail.com>
Date: Mon, 9 Dec 2024 09:06:15 +0100
Subject: [PATCH] Core: Lerp(Color)

---
 reference/LinearInterpolation/LinearInterpolation.cpp | 6 +++++-
 uppsrc/Core/Color.cpp                                 | 8 ++++++++
 uppsrc/Core/Color.h                                   | 2 ++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/reference/LinearInterpolation/LinearInterpolation.cpp b/reference/LinearInterpolation/LinearInterpolation.cpp
index f0c60bf4b..31788534f 100644
--- a/reference/LinearInterpolation/LinearInterpolation.cpp
+++ b/reference/LinearInterpolation/LinearInterpolation.cpp
@@ -6,13 +6,17 @@ using namespace Upp;
 
 CONSOLE_APP_MAIN
 {
-	StdLogSetup(LOG_COUT);
+	StdLogSetup(LOG_COUT|LOG_FILE);
 	
     DUMP(Lerp(10, 20, 0.5));
     DUMP(Lerp(10.0, 20.0, 0.25));
     DUMP(Lerp(Point(10, 20), Point(30, 40), 0.5));
     DUMP(Lerp(Size(100, 200), Size(300, 400), 0.5));
     DUMP(Lerp(Rect(0, 0, 100, 100), Rect(100, 100, 200, 200), 0.5));
+
+    DUMP(Lerp(Color(100, 200, 150), Color(200, 100, 120), 0.5));
+    DUMP(Lerp(Color(100, 200, 150), Color(200, 100, 120), 1.5));
+    DUMP(Lerp(Color(100, 200, 150), Color(200, 100, 120), -1));
 }
 
 
diff --git a/uppsrc/Core/Color.cpp b/uppsrc/Core/Color.cpp
index 7e8bb1737..428c914c7 100644
--- a/uppsrc/Core/Color.cpp
+++ b/uppsrc/Core/Color.cpp
@@ -307,6 +307,14 @@ Color Blend(Color c1, Color c2, int alpha)
 	             min(((a * (c2.GetB() - c1.GetB())) >> 8) + c1.GetB(), 255));
 }
 
+Color Lerp(Color a, Color b, double t)
+{
+	auto Ch = [&](byte a, byte b) {
+		return (byte)clamp(Lerp((double)a, (double)b, t), 0., 255.);
+	};
+	return Color(Ch(a.GetR(), b.GetR()), Ch(a.GetG(), b.GetG()), Ch(a.GetB(), b.GetB()));
+}
+
 INITBLOCK {
 	Value::SvoRegister<Color>("Color");
 }
diff --git a/uppsrc/Core/Color.h b/uppsrc/Core/Color.h
index ea7cc2f4e..17b56ce54 100644
--- a/uppsrc/Core/Color.h
+++ b/uppsrc/Core/Color.h
@@ -166,6 +166,8 @@ double ContrastRatio(Color c1, Color c2);
 
 Color  Blend(Color c1, Color c2, int alpha = 128);
 
+Color Lerp(Color a, Color b, double t);
+
 String ColorToHtml(Color color);
 Color  ColorFromText(const char *s);