From f8c5f3a69cb52d9d0d7d6fada20df45dc03c0d2c Mon Sep 17 00:00:00 2001
From: Mira Grudzinska <mira@lottiefiles.com>
Date: Thu, 10 Apr 2025 05:13:52 +0200
Subject: [PATCH] lottie: follow path stabilization++

* lottie: fixes in follow path

Each time the 'updateText' was called, the mask
path (if the follow path existed) was appended
to the previous one, causing it to grow infinitely.
A 'clear' call on the existing path was missing.

The positions on the follow path for distances larger
than 2 x mask path length were not correctly calculated.

* lottie: fix crash on follow path

It could happen that the searched text position
(distance from the start pointt) on the follow path
was exactly equal to the path length. In such a case,
the cmds pointer pointed to the last element, and in
the next iteration, this caused a crash.
---
 src/loaders/lottie/tvgLottieModel.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/loaders/lottie/tvgLottieModel.cpp b/src/loaders/lottie/tvgLottieModel.cpp
index b1a817a5..5fb1b89b 100644
--- a/src/loaders/lottie/tvgLottieModel.cpp
+++ b/src/loaders/lottie/tvgLottieModel.cpp
@@ -65,6 +65,7 @@ float LottieTextFollowPath::prepare(LottieMask* mask, float frameNo, float scale
 {
     this->mask = mask;
     Matrix m{1.0f / scale, 0.0f, 0.0f, 0.0f, 1.0f / scale, 0.0f, 0.0f, 0.0f, 1.0f};
+    path.clear();
     mask->pathset(frameNo, path, &m, tween, exps);
 
     pts = path.pts.data;
@@ -109,10 +110,10 @@ Point LottieTextFollowPath::position(float lenSearched, float& angle)
     };
 
     //beyond the curve
-    if (lenSearched > totalLen) {
+    if (lenSearched >= totalLen) {
         //shape is closed -> wrapping
         if (path.cmds.last() == PathCommand::Close) {
-            lenSearched -= totalLen;
+            while (lenSearched > totalLen) lenSearched -= totalLen;
             pts = path.pts.data;
             cmds = path.cmds.data;
             cmdsCnt = path.cmds.count;
@@ -147,7 +148,7 @@ Point LottieTextFollowPath::position(float lenSearched, float& angle)
 
     while (cmdsCnt > 0) {
         auto dLen = length();
-        if (currentLen + dLen <= lenSearched) {
+        if (currentLen + dLen < lenSearched) {
             shift();
             currentLen += dLen;
             continue;