From 078b1c8d8671faad1678245f8e01c4c6443d76d0 Mon Sep 17 00:00:00 2001
From: Mira Grudzinska <mira@lottiefiles.com>
Date: Thu, 22 Aug 2024 19:37:42 +0200
Subject: [PATCH] common: uint8_t version of the lerp

An uint8_t version of the lerp function
is introduced to handle cases where
the interpolation factor t exceeds 1, which
previously caused overflow issues due to casting.
---
 src/common/tvgMath.cpp | 12 +++++++++++-
 src/common/tvgMath.h   |  2 ++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/common/tvgMath.cpp b/src/common/tvgMath.cpp
index 2b2f1b32..6275554a 100644
--- a/src/common/tvgMath.cpp
+++ b/src/common/tvgMath.cpp
@@ -363,4 +363,14 @@ float Bezier::angle(float t) const
     return rad2deg(tvg::atan2(pt.y, pt.x));
 }
 
-}
\ No newline at end of file
+
+uint8_t lerp(const uint8_t &start, const uint8_t &end, float t)
+{
+    auto result = static_cast<int>(start + (end - start) * t);
+    if (result > 255) result = 255;
+    else if (result < 0) result = 0;
+    return static_cast<uint8_t>(result);
+}
+
+}
+
diff --git a/src/common/tvgMath.h b/src/common/tvgMath.h
index 71509d57..3d020929 100644
--- a/src/common/tvgMath.h
+++ b/src/common/tvgMath.h
@@ -286,6 +286,8 @@ static inline T lerp(const T &start, const T &end, float t)
     return static_cast<T>(start + (end - start) * t);
 }
 
+uint8_t lerp(const uint8_t &start, const uint8_t &end, float t);
+
 }
 
 #endif //_TVG_MATH_H_