From b723ddd72bd48ff04c1d21743f09dd6ba8c5b6f0 Mon Sep 17 00:00:00 2001
From: sparklejin <1575275976@qq.com>
Date: Sat, 30 May 2026 15:53:54 +0800
Subject: [PATCH] imgproc: fix floodFill simple path never being used
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  The is_simple check used mask.empty() after the default mask
  had already been created, making it always false. This caused
  the fast path (floodFill_CnIR) to be dead code — every call
  went through the slower gradient-based path (floodFillGrad_CnIR).

  Fix: save _mask.empty() result before auto-creating the default
  mask and use it for the is_simple check.
---
 modules/imgproc/src/floodfill.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/modules/imgproc/src/floodfill.cpp b/modules/imgproc/src/floodfill.cpp
index 5ef019fb0f..262b539f74 100644
--- a/modules/imgproc/src/floodfill.cpp
+++ b/modules/imgproc/src/floodfill.cpp
@@ -494,7 +494,8 @@ int cv::floodFill( InputOutputArray _image, InputOutputArray _mask,
     if( connectivity != 0 && connectivity != 4 && connectivity != 8 )
         CV_Error( cv::Error::StsBadFlag, "Connectivity must be 4, 0(=4) or 8" );
 
-    if( _mask.empty() )
+    bool noUserMask = _mask.empty();
+    if( noUserMask )
     {
         _mask.create( size.height + 2, size.width + 2, CV_8UC1 );
         _mask.setTo(0);
@@ -508,7 +509,7 @@ int cv::floodFill( InputOutputArray _image, InputOutputArray _mask,
     Mat mask_inner = mask( Rect(1, 1, mask.cols - 2, mask.rows - 2) );
     copyMakeBorder( mask_inner, mask, 1, 1, 1, 1, BORDER_ISOLATED | BORDER_CONSTANT, Scalar(1) );
 
-    bool is_simple = mask.empty() && (flags & FLOODFILL_MASK_ONLY) == 0;
+    bool is_simple = noUserMask && (flags & FLOODFILL_MASK_ONLY) == 0;
 
     for( i = 0; i < cn; i++ )
     {